Dehan Intellectual Technology Co.,Ltd.

-- 2017-05-21 P1: Demonstration of Fabricating and Construction Standard drawings (PDF CAD) for DH Advanced Quick Prestressed Concrete Pile (PLV1A).

Fri, 25 Jun 2021 21:51:12 +0800

2017-05-21 P1: Demonstration of Fabricating and Construction Standard drawings (PDF & CAD) for DH Advanced Quick Prestressed Concrete Pile (PLV1A). – Update @2017-05-21

Note: The readers shall know that most content of this paper is translated from original traditional chinese version by software.

Dehan release the fabricating & construction standard drawings (PDF & CAD file) for DH advanced quick prestressed concrete pile (PLV1A).

The download files (English version of rev.C6E) (update on 2017-03-21s)

In order to make the first-level of the P series technology (DH PLV1) widely known,

We released their fabricating & construction standard drawings (include PDF & DWG files) of type PLV1A & PLB1B on our official website. Only type PLV1A is released for the english version.

Please be kind to advise us and give guidances.

Remarks:

1. The type PLV1A is a standard type of the DH pile (PLV1). Limited to the hollow hole size inside the pile, it is recommended to produce net less than 400mm pile diameter.

2. The type PLV1B is a compacted type of type PLV1A, can be made more than 300mm pile diameter pile, suitable for each pile diameter.

3. The pile of type PLV1A/PLV1B apply to the implant construction method (drill method for PC/PHC pile).

4. The pile of type PLV1A/PLV1B apply to Taiwan specifications.

Email: service@dehantech.com

Download the files:

(1) The fabricating & construction standard drawingd of type PLV1A - DH advanced quick prestressed concrete pile:

Taiwan Specifications -

Traditional Chinese version: PDF file, AutoCAD file (ZIP archive) (2017-03-21 update, Rev.C6)

Simplified Chinese version: PDF file, AutoCAD file (ZIP archive)

English version: PDF file, AutoCAD dwg file (ZIP) (Rev.C6E) [* Note 2]

(2) The fabricating & construction standard drawingd of type PLV1B – Compacted DH advanced quick prestressed concrete pile:

Taiwan Specifications -

Traditional Chinese version: PDF file, AutoCAD file (ZIP archive) (2017-03-21 update, Rev.C6) [* Note 1]

[* Note 1] We found in the customer feedback, the new DH pile (PLV1A) has many advantages in the mechanics and duration than the traditional pile. Our customers do not like those traditional pile type. So, we would not update drawings of type PLV1B from Rev. C6 (Upd. @ 2017-05-18)

[* Note 2] English version of the drawings is due to the strong request of overseas friends. We are directly translated them from the Traditional-Chinese version, for reference. Some of the translations of the prefessional nouns will be different, will vary It can only be used for reference. (Upd. @ 2017-05-21)

-- DH Quick Pile Introduction Video (on Youtube) - Update @ 2018-04-07

Fri, 25 Jun 2021 21:51:12 +0800

DH quick pile -- Youtube videos

update: 2018-04-07

Note: The readers shall know that most content of this paper is translated from original traditional chinese version by software.

001 - The friction wrap design between the cap and the pile is really stable for a long time?

002 - According to the regulations, the water ash floating layer on the inner wall of the pile is required to remove the hair
https://youtu.be/6qyQDSdI4Xc

003 - Pile and core-filled concrete _ friction gripping effect shows a simulation test of unstable factors
https://youtu.be/9ZqX1TzfAyA

004 - DH-PHC pile replaces unstable friction grip mechanics with reinforced concrete structural mechanics
https://youtu.be/xD4vgtiEXhA

005 - DH-PHC piles save time and money quickly construction method
https://youtu.be/BxcvSS4K3eU

006 - Foam layer and inferior concrete co-adhesive effect (DH-PHC overcomes unstable pile head treatment)
https://youtu.be/swzXDrTjJ8o

007 - Defects in traditional pile head treatment (DH-PHC piles improve their loss and strengthen the structure)
https://youtu.be/uZRGAVlMaxA

008 - Defective improvement of traditional pile head treatment (DH-PHC pile - never loosening pile head treatment)
https://youtu.be/vxmpYB3O9rE

009 - Current implanted pile heads
https://youtu.be/B_qwX9cb8Qs

010 - DH-PHC piles ~never loosen pile head (reinforced concrete structure)
https://youtu.be/lwhKQdlgY1o

011 - DH-PHC pile construction procedure (pre-emptive pile head treatment)
https://youtu.be/Mte8QaQPyiE

012 - DH-PHC never-loose pile head treatment (improvement of pre-stressed pile head friction grip design replaced by structural mechanics)
https://youtu.be/AXgp_1E6vY

013 - Pile head treatment technology for DH-PHC piles (effect of high frequency reverse vibration on buildings or equipment)
https://youtu.be/YlaL8exx6wg

014 - DH-PHC comprehensively solves the instability and uncertainty of current implanted pile heads
https://youtu.be/3RpZK3JPy3o

015 - DH-PHC pile (compression project float time, and the pile head never looses)
https://youtu.be/BS8KEOGpuTk

016 - DH-PHC pile (strengthening the stability of the pile head)
https://youtu.be/SOK7i_fIkJo

017 - DH-PHC never-loosen pile head treatment
https://youtu.be/mjtAmt_S3q0

018 - The structure and construction method of the current implantable phc piles should be improved? The DH-PHC pile quality is more stable, which is beneficial to the project contractor's bidding competitiveness, reducing costs and risks, and is more conducive to investment. Recovery rate of funds and ensuring benefits
https://youtu.be/ENqy2x6Mlg4

019 - DH-PHC pile vent pipe piping phenomenon
https://youtu.be/aLnWlm61bsA

020 - DH-PHC pile hollow pile head venting phenomenon
https://youtu.be/5ukYZyUJ0no

021 - DH-PHC pile easy opening method
https://youtu.be/sJf7eNLV9Bs

022 - DH-PHC implantation process (drilling to bearing soil layer)
https://youtu.be/w02PVxccGdM

023 - DH-PHC pile (hollow pile head implantation process without secondary drilling core processing procedure)
https://youtu.be/1PhULZstdeo

024 - DH-PHC piles, anti-seismic, anti-pull, never-loosed pile head treatment
https://youtu.be/mZv1BRgiMxE

025 - DH-PHC piles Strong and resistant to pulling and never loosening
https://youtu.be/0Ixa-KYGQ1Q

026 - DH-PHC pile quick construction method
https://youtu.be/XJY5V4xA4nU

027 - DH-PHC pile pre-formed hollow pile head treatment
https://youtu.be/YU71uQfISdM

028 - DH-PHC piling process
https://youtu.be/Uw_sP-Muh_k

029 - DH-PHC piles ,How to unhook the implant positioning and auxiliary cable (po: 2017-04)
https://www.youtube.com/watch?v=S-qSv6xYxXY

030 - DH Quick Pile (Comparison of Implanted Pile) (po: 2017-05-05)
https://www.youtube.com/watch?v=5TeriVmNH20

031 - DH-PHC hollow pile head treatment
https://www.youtube.com/watch?v=uH2hTItDWq8

032 - Analysis of the wear and tear of the inner wall of the pile and the core-filled concrete
https://www.youtube.com/watch?v=Mpo252RQOps

033 - DH-PHC 600# 14ML single pile implantation process
https://www.youtube.com/watch?v=cUhgdnnXouc

034 - PHC piles, anti-seismic type, never loosen pile head treatment
https://www.youtube.com/watch?v=W0L6TbhmxV0

035 - DH-PHC pile application for deep foundation of residential area in liquefaction potential area
https://www.youtube.com/watch?v=ZBH47-rmEVY

036 - PHC piles ,implanted with different machines in response to the needs of the site
https://www.youtube.com/watch?v=QXiKIinoRgE

037 - PHC quick method (compression schedule time, strengthening pile head mechanics)
https://www.youtube.com/watch?v=wbzvPt_ACGs

038 - DH-PHC quick method (discussion on the case of traditional implanted piles) (@2017-11)
https://www.youtube.com/watch?v=rcZ1cB4LYrQ&t=145s

039 - Defective phenomenon of implanted piles (DH-PHC never looses pile head treatment)
https://www.youtube.com/watch?v=ayHu53sB6U8

040 - DH quick pile, site of gravel layer
https://www.youtube.com/watch?v=F3cp3rqAFeM

041 - DH quick piles, Extreme compression of the period
https://www.youtube.com/watch?v=bJi_wtvpofk

042 - Gravel layer digging method, implanted pile construction (DH quick pile series)
https://www.youtube.com/watch?v=Qo3iZacdd-I

043 - Traditional pile head treatment problem solution (DH quick pile easy opening method)
https://www.youtube.com/watch?v=xXs0z80L0Fs

044 - Pile core pull failure of traditional pile head treatment (DH quick pile overcomes traditional defect problems)
https://www.youtube.com/watch?v=Aw7lSSIRcQY

Continue to increase......

Google+ Video：
https://plus.google.com/111604789290117346773

-- DH Quick-bending introduction video (on Youtube) - update @ 2018-10-10

Fri, 25 Jun 2021 21:51:12 +0800

DH Quick-Bending Introduction Video (on Youtube & Others)
- update @ 2018-10-10

Note: The readers shall know that most content of this paper is translated from original traditional chinese version by software.

001 - Ying Zhang Heavy-Cold-Pipe-Bending (06:40)
https://www.youtube.com/watch?v=wusjMXoxztI

002 - 2018-09 Quick-Bending technical brief on KIMD expo. (03:57)
https://www.youtube.com/watch?v=5cJwyQ-RJgE

FB-001 - 5" stainless pipe bends cold processing "remaining material", rebirth bend signboard (industrial style) (02:26)
https://www.facebook.com/231191687251946/videos/552005825170529/

P8B: part.2 Energy Strategy on Island Defense

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Plan for Island defense energy strategy

As the title.

If necessary, please come to inquire.

P8A: part.1 Sunshined Dark Forest Project

Fri, 25 Jun 2021 21:51:12 +0800

P8A: Sunshined Dark Forest Project intoduction

Note: The readers shall know that most content of this paper is translated from original traditional chinese version by software.

Forword

The Shining Dark Forest Project is the first sub-plan (part.1) of DH SolarTree technology based on the practical area, with a capacity of 16.0 GW and a power generation of 20.4 billion kWh. (Reference: The total power generation of Taipower No.3 Nuclear Power Plant in 2010 was 15.3 billion kWh. The estimated power generation of two units in the Taipower No.4 Nuclear Power Plant is about 23.6 billion kWh/year)

In this land, we have lived for a long time, very beautiful, and people are working hard. However, natural resources are not rich enough. DH solar tree technology is used to fill some resource defects. Basically, it is simply a tailor-made technology for the local.

Perseverance is the goal of mankind, but there is no need to blindly enter. This is also the philosophy of our efforts. As a long-term engineering person, in addition to spending money (it must be required), it can sometimes be said to be a form of "destruction of the status quo", so it will cause some negative views of the average person, but sometimes it has to be done. See if its successor can create better benefits or utility to determine its positioning.

(*This paper is not finished) --- upload soon

Technical Consultant:

　　email: service@dehantech.com

P8: DH SunTree

Fri, 25 Jun 2021 21:51:12 +0800

P8: DH-SunTree

Create: 2018-06-14 , Update: 2018-07-01

Note: The readers shall know that most content of this paper is translated from original traditional chinese version by software.

In June 2018, Dehan launched the latest technology in the P series: P8.

The basic concept of the DH SunTree:

Style 2 is a specially designed style for the Western Pacific (wind reduction).

Applications of DH SunTree:

    The use of two sets of technologies that are already very mature and cheap in the engineering world: pre-stressed piles and steel frames.
    To obtain a lot of land to use.
    The high-tech solar modules are instead identified as components that can be obtained in the free market.

    Our pleasure lies in finding/searching for the worst, worst, and least desirable land.
    Land with the lowest or negative interest, once again activated or reused,
    And it is the rapid use and development ("time" is one of the key points of our technology, "land" is another).

The original idea was to use highway shoulders or railroads, but this is not our best/final goal.

    For example, a 500mmX12m single-section pre-stressed pile spanned @8M is used, and each work shift is about 30-40 sets per day (240m road length, excluding environmental impact). Locally, at least 20-30 sets of work can be started, and the estimated daily advance is 7,200 meters. The construction needs (100,000 pieces) of green land on both sides of the road with a length of 400KM, and the whole line can complete the operation as fast as 120-180 days.
    The steel frame is modularized in mass production and installation, and the solar panels are also in the same place. Eaen with slight errors, the construction speed is very fast. This can be done in other ways, as long as the sunshine can be accepted.
    This design is extremely advantageous for the transmission and distribution operations in the latter stage, which is different from the general star-type citizen power generation application level.
(The above estimates only, please don't worry too much).

Compared with the delicate solar panels, the cost of these piles and steel frames is already insignificant.
These piles and steel frame costs are even less than the time when the land is difficult to obtain and the day is abolished.

The characteristics of the pre-stressed piles are quickly prefabricated in the production line of the factory. If the 24H operation is even up to 1-3 turns. High strength, once-ground and underground construction (fast speed), no excavation on site, no stacking of construction materials, rapid restoration of ground, low cost, durability up to 100 years (replacement of solar panels 5 times). If you are on the road, it will not affect the car driving.

However, on the road(highway), although the area is large, Sorry still can't satisfy our design demand.
Joining the railway (orbit,MRT) implementation, although good, is still not enough to meet the point of satisfaction.

We thought about... Using useless open space (very vulgar ideas, close to the status quo).
But still can't reach the point of satisfaction. Moreover, there are many problems.

A more ideal solution is... The DH Dark Forest Project

The DH SunTree is mainly shaped by the trunk and the leaf exhibition. The imitation big tree absorbs solar energy on the face, so it is named.

The most distinctive one is the "pre-stressed pile" that is not eye-catching and serves as a trunk. This is an extremely mature building material, which facilitates rapid and large-scale prefabrication.
Pre-stressed piles are the ultimate application of reinforced concrete in civil engineering, using high-strength concrete (such as fc'=800kg/cm2, nearly 12,000psi) and high-strength steel bars (referred to as pre-forced steel bars, such as fy=12,500 Kg/cm2), forming an excellent "support structure", and the concrete has excellent weather resistance (refer to steel structure or steel pipe), relatively low cost, can be used to "plant" our "DH Suntree".

The steel frame is also a mature steel structure product. It is fast prefabricated, fast installed, and hot dip galvanized protection, so that the steel frame can support the life of the energy board (PV panels) as much as possible and reduce the cost. The type is uniform, the size is set, and it is suitable for mass production.

These are materials and technologies that can be obtained locally, without the need for external forces.

When our land resources are extremely deficient, it can be used. We also use it to build a "Sunshining Dark Forest."

Let's plant a tree.

    Planting trees is a pleasure.
    Others plant trees, using fertilizer, watering, and loving care, so that small saplings can grow up.
    Our SunTree is made of steel, cement and iron bones. If it is hot, it will help it to play a parasol, but love is the same.
    If every friend has a heart and a tree, you can make a big forest.

Note:
(1) This graphic is an engineer's manuscript. It has been ugly without editing. Don't mind too much.
(2) Please see "Dark Forest Project" for details.
(3) If you feel that there is any missing in DH SunTree technology , please let us know and we will make it more progressive.

The real focus is here...

It's designed for the Taiwan's environment

    DH SunTree Technology is an energy technology designed specifically for the characteristics of Taiwan.
    Taiwan has a lot of problems of environment, lack of energy, small land, strong typhoons, many environmental protests, and many many opinions. This is exactly the environment in which Taiwan is located.
    However, energy is still necessary.

Taiwan's economic environment is not bad, which means that her financial status still is fine.
The biggest problem with solar power is that ........ "lacks of land".

Don't think too much about the DH SunTree, but it's not too simple.
It is not high-tech, it is a vernacular, it is a set of land use technology.

In Taiwan, the most expensive cost of solar power generation is not PV solar modules, but "land".
Land is also the biggest unknown in conflict. It is not only "expensive", but also more difficult to "acquire" and "agree to obtain".

Almost all use of Taiwanese technology

    Looking at the DH SunTree technology, there are mainly civil, steel, and electromechanical technologies.
    Electromechanical technology (mainly solar panels) is a common material that is designed to be sourced from the market and does not have to be included in this technical discussion.
    The rest of the technology, the locals are enough to support. Basically, no foreign technology is used.
    Compared to the delicate solar panels, other building materials are relatively cheap materials, which is a very important cost point of view.

In solar power generation, a number of star-studded power generation methods have many problems in the acquisition end (including transmission and distribution), operation and maintenance, etc.

DH SunTree is different from small power generation mode. It adopts a larger area of power generation, which makes capacity and management more capable of large-scale and large-scale production, and is conducive to the matching of various subsequent constructions. At the same time, the builders and operators in the design concept are also different from the tradition. This is a big difference from the traditional solar power generation in the local area. It is necessary for everyone who wants to be careful to think about it again.

The smart friends can probably find that the materials used in the DH SunTree are the currently used and the cheapest engineering materials.

Construction investment (capital investment) can be carried out in several stages, and stopping or continuing is a viable option.

The implementation of the DH SunTree, mainly on the land, can be adjusted according to the tightness of the funds (financial), without the need to rush. Of course, it also includes the wishes and considerations of implementing local governments and people.

The land that builds the DH SunTree is close to

The DH Sun Tree is an elevated solar power plant, and the land below can be freely used (of course, there are some restrictions). Residents and tourists can make considerable use of the space below, which will change the sense of deprivation caused by traditional solar facilities and human society.

It is also feasible to abandon the built-up DH SunTree (for example, land for other purposes)

In places where land is scarce, there are other needs that are added to the land at any time. Solar power generation is a way of generating electricity that requires a lot of land. So we designed this technology to make the land useable, instead of dedicated, exclusive, exclusive, and wasted social resources.

Most importantly, the DH SunTree uses almost exclusively the lowest value, or no use of land in society.

This depends directly on the application we envisioned --
Shining Dark Forest, or Island Defense Energy Strategy.

The technology itself is colorless (Not related to politics), so don't worry too much.

(continuously updated...)

Download:

1. Introduction to DH SunTree. (Traditional Chinese version) (simplied Chinese version) (English version)

Technical Consultant:

　　email: service@dehantech.com

2018-08-03: Dehan had a technical briefing at the headquarters of Taipower Co. (PPT)

Fri, 25 Jun 2021 21:51:12 +0800

2018-08-03 Dehan Company had a large engineering technical briefings and extensive technical exchanges in the General Management Office Building of Taipower Company.

Download:

　Specific organization - briefing Information pdf file (Traditional Chinese version - 10.0MB)
　Specific organization - briefing information ppsx file (Traditional Chinese version -14.5MB)

Technical Consulting:

　email: service@dehantech.com

2018-02-06 Some Notes for Hualien Earthquake

Fri, 25 Jun 2021 21:51:12 +0800

Remind everyone to pay attention to the terrible earthquake and prevent early prevention for their beloved family

create: 2018-02-12 , update:2018-09-08

Note: The readers shall know that most content of this paper is translated from original traditional chinese version by software.

Excerpt report:

1. Source: Wind Media 2018-02-07, http://www.storm.mg/article/396610

Li Hongyuan said in the live broadcast of "ETtoday News Cloud" on the 7th day that due to serious soil liquefaction in the north, if the earthquake of magnitude 6.0 in the north occurs in the north, I am afraid that it will knock down 4,000 houses.

If the Taipei encounter an earthquake of 7.3 grade, 35,000 houses will fall.

Li Hongyuan said: "From 921 Earthquake disaster to Tainan Earthquake disaster(2017) to this time, Hualien Earthquake disaster(2018) is actually the same scene. Everyone speaks the same thing. I am very upset." He said that he has warned the Ministry of the Interior affairs about high potential danger of the soil liquefaction in Taipei. If the earthquake with a grade of 6.0 , it will probably dump 4,000 houses. In case it is 7.3, you will have to dump 35,000.

2. Taiwan fault map

▲Source: Institute of Applied Geology, Central University
http://volcano.gl.ntu.edu.tw/worldwide/taiwan_faultmap.htm

▲Source: Central Geological Survey, Ministry of Economic Affairs
http://fault.moeacgs.gov.tw/ATTeach/地震活動觀測/motive.htm

▲The probability of earthquakes in Taiwan's seismogenic structure in the next 50 years
(Source: Ministry of Science and Technology Taiwan Earthquake Model Team 2015)

3. Taiwan's soil liquefaction potential
(by the way, the relevant soil liquefaction potential is together, Taiwanese are too easy to forget)

Source: Central Geological Survey of the Ministry of Economic Affairs - Geological Cloud - Soil Liquefaction Potential (Check @ 2018-02-12)
https://www.geologycloud.tw/map/liquefaction/zh-tw

Taipei City, Chang-yun, Tainan City, Kaohsiung City

However, the following URLs may be more acceptable to the general public:
Central Geological Survey of the Ministry of Economic Affairs - Soil Liquefaction Potential Inquiry System
　　https://www.liquid.net.tw/CGSSL/Public/process/Mainpage.aspx
　　https://www.liquid.net.tw/CGS/Web/Map.aspx

Distribution of soil liquefaction potential in all counties and cities of Taiwan (Source: Central Geological Survey)

~~ There are many things we can't change, but there are some things we have the ability to prepare in advance~~

For ... people who love me, and people who I love,
Not just... the money I love.

Remember - Hualien - Strong feeling @ 2018-02-06

Just remember:

2018.02.10 [Sisy's World Weekly Report] Soil Liquefaction - 311 Chiba Pu'an History Lessons
https://www.youtube.com/watch?v=HcpEuix7XQU

2018.02.10 [Sisy's World Weekly Report] Potential threat away from the epicenter
https://www.youtube.com/watch?v=cDDeEq6fglI

2018.02.11 Zhongtian investigation report / "mountain foot fault" if turned over, 9 million people in Beitai suffered from sputum, and the incidence rate in the south was 64%
https://www.youtube.com/watch?v=HtJDusYONaU

2018.09.07 The liquefaction of the eternal volcanic ash The life of the "Dark City" of Hokkaido - Japan / Hokkaido earthquake of magnitude 7 - Basin soil liquefaction
https://www.youtube.com/watch?v=FGR2JFby1vU
https://www.youtube.com/watch?v=ybBG7T4UBzk&t=746s

B1 - Case Study (5) - High Pressure Resistance Review of DH Quick-Bending

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Case Study (5) - High Pressure Resistance Review of DH Quick-Bending

Lee Shengnan / Deputy General Manager of Dehan Intellectual Technology Co., Ltd.
date : 2017-10-29

Note: The readers shall know that most content of this paper is translated from original traditional chinese version by software.

Summary

The plant's pipeline system provides the flow of pressurized fluid contents, which is a very important property that must be met by the pipeline system. This article will explore the implementation effectiveness and high pressure resistance review of Dehan's "Quick-Heavy-Cold-Pipe-Bending" technology (hereinafter referred to as DH Quick-Bending) by a recent implementation case. DH Quick-Bending technology is a kind of industrial piping operation that uses a lot of manpower. It uses a large-scale digital elbow processing machine developed by modern technology to carry out a large number of improved elbow joints to reduce costs and reduce construction time. Improve quality, reduce quality inspection load, reduce future maintenance, improve plant operation safety, improve fluid fluency in pipelines, and improve pressure resistance.

Keywords: Quick-Heavy-Cold-Pipe-Bending, Quick-Bending, Dehan

Forword

In the previous case: "High Security Review of DH Quick-Bending" [2], we reviewed the high-pressure oil and gas pipelines in the case, caused by micro-damaged weld cracks in one of the hundreds of elbow ring-welded joints. In the actual case: "High-fluency review of DH Quick-Bending" [3], the inner wall surface of the process pipeline in the case was reviewed, and the process pressure loss caused by the weld bead protrusion welded by the ring mouth was missing.

At the technical level of the DH Quick-Bending, the two problems frequently asked by the owner and the design unit are: the residual stress after cold bending, and the pressure resistance after cold bending. The former has been mentioned in the previous article [1] [2] [3], the latter is the subject of this article review by the case, in order to explain the Quick-Bending technology.

In this paper, the two 1.25” sch.160 hydraulic pipes shown in Fig. 0-1 are used as the main body to illustrate the high pressure resistance (inner pressure) characteristics of the DH Quick-Bending. For easy reading, more photos will be explained to avoid essays and academics.

Fig. 0-1: 1.25” sch.160 pipeline

1. The traditional industrial piping method

1.1 How the traditional factory pipeline system works

In the operation of the plant, the production material or the operating material must be transported from one end to another end by means of a pipeline, and the materials (the contents of the pipeline) are fluids, liquids, or powders, or mixed fluids, etc., Otherwise, it cannot flow in the pipeline. In order for these pipeline contents to flow, a pressure flow must be used, the most common way being pumping with a pump. (Note: This article takes the steel industry pipeline as an example, but mainly explains the petrochemical industry factory pipeline system)

The production process has a certain amount of stable demand for the "supply amount" of the pipeline contents, and the pipeline contents must reach a specific flow speed within a certain period of time in order to meet the process reaction requirements. Using a simple fluid mechanics formula: Q=V*A, when the pipeline area (A) is fixed, to increase the flow rate (Q), it can only be treated by increasing the flow speed (V). To increase the flow speed, only the fluid pressure can be increased, so the factory pipeline fluid is mostly a pressure flow; of course, there are also a few gravity flows, such as some sewage drainage pipelines (Note: these are not the main pipeline types of the plant).

The greater the pressure of the contents of the pipeline, the greater the pressure inside the pipe wall. The pressure inside these pipes is designed to be used as the basis for selecting the material, pipe diameter and grade (wall thickness). For pipelines of the same material, the greater the pressure, the greater the required wall thickness (the more expensive the price).

The internal pressure of the general process fluid is still relatively small. If it is a fluid line for operation, such as a hydraulic pipe for mechanical operation, there is still a need for kinetic energy to push other equipment (such as a hydraulic cylinder or a brake). That is to say, in addition to the requirements of conveying flow, there is still a demand for conveying power, and the speed of fluid transfer is generally "super fast" in order to meet the needs of mechanical instantaneous operation. Therefore, the internal pressure of these hydraulic cylinders for mechanical operation will be very high, usually much higher than the pressure required for the factory process piping. For the pipeline system, the material strength of the pipeline and the wall thickness of the pipeline are higher.

When the pipeline is subjected to a large fluid pressure in the pipe, it is usually designed with material strength and wall thickness. The material may be related to the physical properties of the pipeline contents. Sometimes it is required to have corrosion resistance, acid resistance and alkali resistance (such as SUS 304, 316, etc.), and the material strengths are different. The rest, it fell to the design of the "wall thickness". (Note: This article only talks about round pipes, not about square tubes)

In the piping practice, the pipeline is not natural (or when rolling finished products) is a complete, curved and natural pipeline, but consists of many parts. In the traditional piping construction, these parts are roughly divided into pipes and elbows except for flanges. The pipeline system mainly combines many straight pipes and elbows and combines them into appropriate lengths and angles to reach the destination end from the source end in the three-dimensional space. These combined means have flange connections, and a small number of low-pressure systems (such as water pipes) can also be combined with male-female threads, but the most important way of joining is still to use welding called ring-welding. In short, it is to use the electrode as a medium to connect the pipelines on both sides (straight pipe or elbow).

These welded joints are sometimes "straight pipe - straight pipe" type, mainly used in the extension of pipelines (the length of the pipeline is generally 6 meters long, there are rolling, transportation, metering considerations), it depends on the stack house, the consumption of materials (especially when special materials are used). Some joints are "straight pipe-elbow" types, which are the main subject of discussion in this paper.

1.2 joint types and weaknesses of "straight pipe - elbow" in traditional pipeline

These "straight pipe-elbow" joint types are mainly used to change the direction of the pipeline. There are plane turns, vertical turns, and a combination of the two (three-dimensional). The angle is mostly 90°, followed by 45°. The turning angle can of course be other specified angles; however, the design work is indepedent. The piping construction is carried out on site, and it depends on the work space of workers. The angles is generally 90°, 45°. In piping construction, the more strange the angle is, the more "thick work" is, and the more expensive it is.

Because the combination of "ring-welding" is work in high temperature (hundreds of degrees Celsius) to melt the electrode and the base metal, in addition to the weld bead itself is the weak point on the joint, the instant high-temperature welding will also make the base material produce material. Embrittlement, weakening, deterioration, and even cracks or sand holes (some related to the craftsmanship/proficiency of the welder), thereby it will reduce the internal pressure capacity of the original pipeline. The design is directly solved by "increasing the wall thickness"(choose another pipe size upward), that is, the pipeline level is adjusted one to two levels to deal with. These are actually letting the weakening factor on the material disappear naturally in the "increased wall thickness".

1.3 Elbow parts in traditional pipeline systems

In the traditional elbow parts, except for the large-diameter elbows, which are made of multi-bend-pieces weld(mitres bend), the small-diameter elbows are mostly manufactured in the processing plant by high-frequency heating elbow type (see Fig. 1-1). It can be seen that the steel pipe (on the right side of the Fig.) is instantaneously heated to a high temperature of softening degree (partially and rapidly increase in temperature can be seen from the curved pipe of the red pass in the Fig.), expansion, bending, cutting, cooling (and rapid cooling?).

Fig. 1-1: Traditional elbows are manufactured by high-frequency heating in a processing plant (source: Youtube)

Fig. 1-2: Traditional elbows, packaging/transportation is quite time consuming [1]

This high-frequency heating elbow processing has several characteristics:

(1) A large amount of electrical energy is required. (energy consuming)
(2) The workplace is hot and the work is dangerous. (labor safety consideration)
(3) After the hot bending of elbow parts, the material will change in tension and extension for temperature, and then shall be cut and trimmed of secondary processing. Due to the high heat of the elbow, it must be reprocessed after the heat is removed.
(4) Only single elbow can be made, and usually a single 90° elbow type; if other angles (such as 45°) are required, it must be cut again (there may be material waste).
(5) After the elbow is completed at the processing plant, it will be packaged and transported to the prefabrication site assembly (see Fig. 1-2). The elbow parts factory belongs to another ordering, and the procedures of consolidation, purchase and preparation of materials, processing, quality inspection (which is questionable), packaging, transportation, etc. all require time/labor to work. It is no wonder that the construction period is lengthened.
(6) If the cooling process is too fast, there is still a high residual stress. (If the cooling rate is too slow, it will affect the factory operation time, space, equipment and manpower)

The traditional piping contractor and elbow factory are different contractor. Usually, elbow parts packed in different manufacturers and to different locations, which is quite laborious (i.e. cost and duration). Don't miss-underestimate the packaging work, it is quite cumbersome for metal elbows, and is time-consuming and costly. When it transportation, the cost must increase. Sometimes, the elbow parts are purchased by the owner or the main contractor, and then the materials are transferred to the piping contractor for construction (shop or site), there will be a transfer/unpacking cost; the delivery is also time-consuming and labor-intensive, and the cost must be increased.

In the pipeline prefabrication, taking the 90° elbow as an example, both of the front and rear ends are welded with the straight pipe by the ring-weld joint [2][3], usually at least one end is prefabricated at the factory, and the other end may be shop prefabricated or site weld (may facilitate re-delivery to the site or installation) (see Fig. 1-3). (Note: Factory prefabricated depending on the location, may be in the piping factory(shop), or in the temporary site (field) set up near the construction site)

Fig. 1-3: Traditional elbows and straight pipes are welded by ring-weld joints (factory prefabricated) [1]

　
Fig. 1-4: Traditional elbow ring welds are more susceptible to cracking [1]

The lack of traditional elbow ring- welding joint has been described in the previous article [1] [2] [3], that’s no longer speak. Before this new technology was developed, the only way to combine industrial pipe construction was the combination of ring-welding.

(1) High temperature connection:

The ring-welding can only be combined with high-strength electrode and steel pipe base material at a high temperature of more than several hundred degrees Celsius. The effect of high-temperature cauterization also destroys the base metal at the same time, making the material embrittlement, deterioration and weakening.

(2) The weld is easily cracked:

The welding of the ring joint adopts the method of full penetration welding. The electrode is easy to oxidize. The adjacent steel base material is also susceptible to oxidation due to the high temperature (because the material has been changed by high temperature). In the factory practice, the part of the ring-weld (which may be an electrode or a steel pipe) has always been prone to breakage, resulting in safety risks (see Fig. 1-4), mainly due to high temperature deterioration of the material.

(3) A large number of professional welders must be used for ring-welding:

Ring-welding is a full penetration welding method, which has many safety concerns (especially for petrochemical plants with explosive dangers), and even does not allow any sand holes at the weld bead. As long as the welder is doing the ring-welding, the professional "hand" stops for 0.5 seconds more or less, or shakes twice, or first smokes then continues welding, etc., will affect the weld quality. The difference (not every worker is "welding god"); sometimes the quality of the welding machine or age of machines will also have an impact to weld quality.
It is not to say that using of labor is not good, but manual work is likely to cause large variations in quality (may be affected by many factors such as weather/rain, mood swings, physical load, tools, safety protection, working space, training level, work experience, etc.). Taking the construction or maintenance of the petrochemical industry as an example, the pipeline welding workload is very high and the construction period is urgent. Many welders must be used, often working overtime, or even rushing through the night, which easily affects quality (risk).

(4) Maintenance of the ring-weld joint is relatively difficult:

The ring-weld joints of the elbows are mostly full penetration welds. Even if the surface of the weld bead is ground, it is not as smooth as the original steel pipe. In terms of coating rust prevention, it is inferior to the anti-corrosion effect of direct blasting and painting on the original surface of the steel pipe, which tends to increase the maintenance amount and increase the risk in the future (see Fig. 1-4).

Taking petrochemical plant pipelines as an example, local factories have attached great importance to safety, but many pipelines in the plant are concentrated and staggered in high density. As long as there is a problem with a pipeline (such as leakage, combustion, explosion, etc.), it is possible Initiating a chain-type accident, burning for several days, or even burning the entire plant, the local case actually exists, and the responsibility for management risk is not small.

2. Case description

Construction site: Kaohsiung City.
Construction classification: steel industry, terminal operation area.
Engineering nature: maintenance.
Special requirements: short construction period.
Use technology: Take Quick-Bending.

　　本文採用該案中的兩條管線來加以簡易闡述。

2.1 DH Quick-Bending can withstand huge pipe pressure

Fig. 2-1: 1.25” sch.160 (thickness 6.4t) hydraulic line (continuous 4 bends), ISO piping diagram

As shown in Fig. 2-1, it is a 1.25” sch.160 (6.4t thick) steel pipe, which is used in the hydraulic line of the dock unloader. The pressure inside the receiving pipe is set to 300 kg/cm2 or more. The purpose of taking these two pipelines as an example is to get rid of the superstitions of many people's consciousness. They always think that the curved part of the cold bending pipe become thinner because the metal pipe is stretched, the pipe wall is changed. And the possibility of danger of pipe cracking will increase.

In practice, in terms of the above pipelines, the pressure required by the owner must be as high as 300 kg/cm2. For the expert, this is a fairly high pipe pressure, which is much higher than the pipe pressure required for the general petrochemical process line system. Of course, this pipeline is an operation pipeline, which is applied to the hydraulic pressure function. Under the requirement of instantaneous operation, the transmission pressure is high and the speed is fast, so there is such a high requirement. (Note: This sch.160 pipeline is quite difficult to see. Some industry workers may have never seen it in the whole life. The owner knows the points, and deliberately finds us.)

The pipe pressure requirement of 300 kg/cm2 can meet the requirements, and other smaller pipe pressure requirements should be ok. This is probably not expected. If there are any dissidents, then it may be necessary to review it: Is it that the concept is too conservative, or that the company budget is too sloppy, the construction period is too loose, and the traditional piping method of old fashion is still used.

We have all entered the 21st century, and we should let the industrial piping industry get rid of the labor-intensive style of industrial 2.0 production pattern, and should step into the ranks of "Industry 3.0". Unfortunately, now DH Quick-Bending still can't catch up the Industry 4.0. But we will continue to improve intelligent integration and aim to move towards Industry 4.0. I believe there should be opportunities.

Of course, DH Quick-Bending have other advantages:

(1) Low cost.
(2) Construction period is short.
(3) High precision.
(4) Strong pressure resistance.
(5) Less maintenance.
(6) Others, please consider it by yourself.

This article uses this small section of high-pressure pipeline as an example to review, in fact, it is only a very simple statement, DH Quick-Bending can withstand huge pressure inside the pipe.

2.2 DH Quick-Bending test of pressure resistance

In the inspection of curved pipes, we recommend two simple methods:

(1) Wall thickness inspection:

After direct straight pipe bending from the metal straight pipe, it can be directly tested (both online and offline). There are many types of thickness test instruments available for sale at the market; one of the thickness gauges currently used in our factory is the Dakota MX-3 Ultrasonic Thickness Gauge made in USA, which can be applied immediately (see Fig. 2-2). If customers have more precise requirements, they can also choose to send them to professional institutions for testing (such as SGS, MIRDC etc.) with credibility (the cost of inspection is inevitable).

We know that, besides the first cooperation, professional test may not be necessary. The same machine, mold, and control program; this process is a reproducible program from a scientific point of view, ensuring that the same material, under the same procedure, can be repeatedly produced the same product. The same straight pipe material (There is not material to be steal, if the owner or the main contractor supplies material and control from the source.), the machine operation is fast, the construction period is not a problem, and it will catch up with your work.

The quality of the pipe bends from the machine is almost the same, so I can't see what material shall be steal. However, if the customer wants to pay for the test, that will be good but spend more cost/time. It is better to go straight to the online inspection.

We can also accept the client's entrustment, check the thickness on a piece-by-piece basis, and make the part history more complete; of course, the operating cost has to be added up (business consideration).

Fig. 2-2: Dakota MX-3 Ultrasonic Thickness Gauge mode in USA

The Fig. 2-3 shows some of the DH Quick-Bending are suitable for steel pipes (variable depending on the material and grade). Fig. 2-4 shows the data of roundness and thinning rate (changes depending on material and grade) after DH Quick-Bending.

Fig. 2-3: DH Quick Bend Thickness Applicable Table (1/2" to 5" pipe size and grade)

Fig. 2-4: Recording roundness and thinning rate data after DH Quick-Bending (1/2" to 5" pipe)(The above table is part of the measured data, the correctness will be determined depending on the circumstances of the case)

(2) Direct pressure test of pipe bends:

Testing is the best way to ensure quality. The pressure test (commonly known as pressurization test) that must be carried out on finished products such as equipment or pressure vessels can be carried out by entrusting third-party inspections (such as the Industrial Safety and Health Associations) to practice the reliability of quality inspection. The finished pipeline can also be verified by a similar pressure test, which is one of the most reliable quality inspection methods.

We can carry out some simple specific water pressure test on specific pipe diameter in our factory (sorry, the equipment in the factory is limited, the inspection is not our profession), which can meet some of the needs of customers.

Of course, customers who require higher and more rigorous results can still send pipe bends to third-party inspections. In the same way, cost and time will increase.

2.3 DH Quick-Bending pipe is very suitable for petrochemical pipeline

As shown in Fig. 2-5, for another real case, the comparison between the traditional elbow used in the petrochemical plant and the DH Quick-Bending. The pipeline material is 2” sch.160 SUS304 grade, which belongs to thick pipeline, high internal pressure and high acid/alkali resistance. It is generally used in process pipelines in petrochemical plants.

In the upper right Fig. of the Fig. 2-5, the difference between the traditional elbow and the DH Quick-Bending can be clearly seen. It is not necessary to wait for the elbow material, directly bend the pipe, and after bending the pipe, the pipe bend can be designed to be welded on the extended straight pipe (under the same conditions, the "straight pipe-straight pipe" weld bead is more than the "straight pipe-elbow" The quality of the weld bead is much better. It saves material loss and, more importantly, saves a lot of manpower and saves a lot of construction time.

Fig. 2-5: Comparison of traditional elbows and DH pipe bends of 2” sch.160 SUS304

There are many kinds of pipelines in the petrochemical industry. The materials, pipe diameters and grades vary greatly. It is inconvenient to give an example. In the above picture, we use photos in comparison to make a simple explanation. The petrochemical industry has higher risks, and the owners are generally conservative. Engineers engaged in professional pipeline design are also more cautious. In the traditional pipeline system, taking elbow parts as an example, the damage occurs mostly in the weld bead of ring-welding (and the adjacent steel pipe base material), rarely occurs in the elbow body and the straight pipe. The reason is mainly due to high temperature welding, which destroys the original material.

The traditional pipeline system must be connected by means of a "straight pipe - elbow - straight pipe" to complete the overall system configuration. Direct bending has actually been available for many years, but why not accept it for the petrochemical industry? The reason is that the previous bending tools (and molds, etc.) are not progressing enough, the output is insufficient, the precision is low, the quality control pipe can not meet the requirements, and only some thin pipes (such as handrails) can be bent, and the safety/quality is not emphasized. Nowadays, DH Quick-Bending technology has emerged. With the more modern digital bending machine, more force output, higher precision, faster work speed and better quality have been able to meet the demands of all kinds of pipe bends, especially It can meet the needs of heavy industrial piping (such as petrochemical industry, steel industry, etc.) and is better. (See Fig. 2-6)

Fig. 2-6: Digital Bending Machine for DH Quick-Bending

The traditional pipeline system must rely entirely on the "straight pipe-elbow-straight pipe" ring- welding joint method, which is time-consuming, labor-intensive, wasteful of materials, and many inspections. In short word, the cost is high, the construction period is long, and the quality is poor. Due to the emergence of DH Quick-Bending technology, the traditional joint method has been changed a lot (still not 100% free of ring-welding work, but the number can be greatly reduced), which can quickly upgrade the local industrial piping project.

3. Conclusion

The four points in para. 1.2 above have been noted in the previous article [1][2][3]. The reason for repeating the statement here is mainly for the purpose of this article: Corresponding to "DH Quick-Bending pressure resistance". As the above, we know that in the case of petrochemical piping, the damage control management of the pressure inside the pipe mainly comes from the destruction of the ring-weld bead and the base material of the ring-weld, but it has not relationship with the thinning of the pipe bends itself.

In order to overcome the lack of these ring-welds, the pipeline system was designed to eliminate defects by thickening and upgrading. DH Quick-Bending pipe is a direct cold bending pipe. The bending process is controlled by high-precision guiding mold. With the precise control of the digital program, basically, the DH pipe bend itself is uniform in material and uniform in wall thickness. Smooth pipe bends, no abrupt damage points (such as weld sand holes, cracks, etc.), there is less loss in the pressure inside the pipe. In the case of standard pipelines, the pressure inside the pipe can withstand much more than the pressure requirements of the pipeline contents.

In addition to the special requirements of art, in industrial production, manual control of product quality and precision control is far less than mechanical control, especially after adding digital control (CNC) mechanism. If you are in long-term work (such as 24HR or urgency work), the mechanical work is on standby, the accuracy depends on the guided mold fixture and program control. The manual work can only work in 3 to 4 shifts (cost is amazingly high, the quality of the product is amazingly low), and its efficiency, precision (quality), and even work safety can not catch up with machines.

The local labor policy and legal regulations are also becoming more rigorous, and it is inevitable to lean toward the labor side, and it is also an ongoing trend among various industrial countries in the world. The DH Quick-Bending technology is honed in decades of work experience, pursuing the optimization of cost, quality, speed and inspection.

The traditional industrial piping industry is neither a service industry nor a manufacturing industry, but an engineering industry. The introduction of DH Quick-Bending technology is to re-regulate the work of the industrial piping industry more like manufacturing, such as factorization, standardization, and process, replacing expensive manpower operations cost with newer, larger pipe bending machines. Pursue higher yields.

References:
[1] Lee Shengnan (2017), “Introduction to DH Quick-Heavy-Cold-Pipe-Bending Technology”, Dehan Company, Taiwan.
[2] Lee Shengnan (2017), “High Security Review of DH Quick-Bending”, Dehan Company, Taiwan.
[3] Lee Shengnan (2017), “High-fluency review of DH Quick-Bending”, Dehan Company, Taiwan.

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Postscript:

In the industrial piping project, the pipeline is not allowed to have any "fracture" or even "micro-crack", because this will cause great safety incidents. Many people's perception of "pipe bends" is still the impression of "pipe bending" in the last century, as if the pipeline is most vulnerable to damage from this bent pipe. In fact, it is true that the strength of the "bent pipe" is inferior to the "straight pipe". However, in practice, "elbow ring-welding" is worse than "bent pipe", and the safety of the work is greater (higher risk). The reason why "elbow ring-welding" is also applied in pipeline design and construction has two main reasons: (1) because there is no better solution until the end of the 20th century. That is: If you don't use it, you don’t have any solutions. (2) In design work, a lot of safety factor has been added to the elbow ring-weld, which is enough to cover the missing, unless ..... (There are many factors, mainly in the artificial face).
The emergence of DH Quick-Bending is to solve these two difficulties. (update @2017-11-07)

B1 - Case Study (3) - High fluency review of DH Quick-Bending

Fri, 25 Jun 2021 21:51:12 +0800

Case Study (3) - High fluency review of DH Quick-Bending

Lee Shengnan / Deputy General Manager of Dehan Intellectual Technology Co., Ltd.
date : 2017-10-08

Note: The readers shall know that most content of this paper is translated from original traditional chinese version by software.

Forword

This article will explore the implementation effectiveness and high fluency review of Dehan's "DH Quick-Heavy-Cold-Pipe-Bending" technology (hereinafter referred to as DH Quick-Bending) through a recent implementation case of a petroleum industry factory. Contrast to the traditional pipe construction that uses a lot of manpower, the DH Quick-Bending technology uses a large-scale digital bend pipe processing machine developed by modern technology to carry out a large number of improved pipebend(elbow) joints to reduce costs, reduce construction time, improve quality, reduce product inspection load, reduce future maintenance, improve plant operation safety, and improve fluid fluency in pipelines.

Keywords: Quick-Heavy-Cold-Pipe-Bending, Quick-Bending, dehan, fluid mechanics, pipe pressure loss

1. Case description

Construction site: Kaohsiung City, industrial zone, petrochemical industry factory.
Construction classification: factory operation area, flammable.
Engineering nature: maintenance.
Special requirements: The construction period strives for minimization and the safety of the fire is extremely important.
Use technology: new pipe is Quick-Bending.

1.1 Discussion of the previous case

In the previous case: "High safety review of DH Quick-Bending" (please refer to Dehan’s official website) [2], we reviewed the new repaired high-pressure oil and gas pipelines in that case, consisting of hundreds of elbows, one of the ring-welded joints has a leak caused by micro-damaged weld cracks to illustrate two simple missing points: (A) welding is not 100% dense and reliable, (B) inspection is not 100% detailed reliable.

At the same time, the safety of traditional elbow welding and DH Quick-Bending is also reviewed by the concurrent conditions of "without welding on pipebend or continuous pipebends” of the "DH Quick-Bending". On the other hand, the comparison side by side, also touched on the difference between these two methods. DH Quick-Bending can provide cost reduction, high duration compression, inspection simplification / construction rapidization, pipeline system safety improvement, subsequent maintenance frequency / amplitude reduction, plant operation risk down, management enhancements, have made the insiders have to shine.

This safety case shows the visual quality of the pipeline, which can be visually and tangibly recognized by the DH Quick-Bending technology. The use of duct metallization and the application of large-scale digital pipe bend processing machines can improve the overall safety of the pipeline system.

1.2 Discussion of this real case

This case will further explore the problem of the inner wall of the pipeline, which is usually the side that cannot directly see by human eyes and touch by hand. Since the contents of the industrial pipeline are pressurized fluids (liquid, gas, or both). In traditional piping systems, they must be welded to extend the length of the pipeline to the specified Tie-in point. The flow of fluid contents in the pipeline is a pressure flow that must be applied to drive. These additional pressures are mostly pumped from the pump. When the fluid flows in the pipeline, pressure loss (commonly referred to as "head loss") occurs, there is frictional pressure loss from the inner wall of the pipeline, and there is pressure loss from the pipeline turning.

This article is to explore the ability of DH Quick-Bending technology to provide pressure loss reduction, which is closely related to the process, in addition to the energy consumption of pumping. Of course, what is directly related to the "efficiency" of the process system and the "maintenance" problem in the later decades of factory.

2. The situation of the actual case

The actual case is to take an exhaust pipe repair in a section of the project as a commentary. (See Fig. 2-1)

2.1 Comparison before and after maintenance

Fig. 2-1: Old exhaust pipe (left side), compared with new exhaust pipe (right side)

In the maintenance of the exhaust pipe shown in Fig. 2-1, at first glance, it seems that there is no special feature, just like the exhaust hood duct in the kitchen at home, it seems to be the level of the plumber in the workshop (don't misunderstand, no depreciation the meaning of). Don't be worry, this is a large-scale petrochemical factory laboratory-grade exhaust pipe. The material is not a general exhaust aluminum pipe, but a 5" SUS304 (OD 141.3 X 3.4t) industrial grade pipe, more detailed introduction shall be discussed later. In the case, this exhaust pipe is one of the whole work of the case, and will be used as a part of the function explanation. Because this pipeline is based on exhaust gas, it is easier to observe and explain than pipeline based on liquid.

After completed the repair (right side of Fig. 2-1), it can be seen that the appearance is much smoother than before the maintenance (left side of Fig. 2-1). The most important point is not the smoothness of the coating on the outer surface of the pipeline, but the smoothness of the streamline(inner fluid), just like the aerodynamic flow of the aircraft. Generally, the more the appearance is streamlined, indicating that the contents of the pipeline can pass with lower resistance when flowing, which means that the frictional resistance becomes smaller, the pressure loss becomes smaller, and the performance becomes better.

2.2 New pipeline production

First, let's take a look at the processing of the new pipeline production.

(1) Drawing simply:

Because it is the maintenance work that the owner entrusts the professional piping contractor, the pipeline drawings will appear first (because the work is not complicated, it is directly expressed in the ISO drawings), as shown in Fig. 2-2. I assume that you are an expert, understand the drawing, and do not have to explain more. If you don't understand, just jump over and see photos below.

Fig. 2-2: ISO drawing of laboratory exhaust pipe

(2) Preparation of materials (pipe):

The pipe material is the industrial piping grade of the petrochemical plant, the material shall be approved by the owner (see Fig. 2-3). The length of pipe is usually 6 meters. The DH Quick-Bending must use the suitable core ejector on the large processing machine, the required spare parts of each size and material pipeline are different.

Fig. 2-3: Preparing the pipe (left side), pipe and suitable core ejector (right side)

(3) Processing the pipe bending:

With the pipe material ready, the machine is also available, let us tame this long object. This article is just a brief introduction, I also don't want the reader to spend too much time studying contents, so I hope to use more pictures to explain it. The DH Quick-Bending prefabrication process, see Fig. 2-4.

Fig. 2-4: Bending pipe production (pipe prefabricated)

To be honest, watching the operation of the DH Quick-Bending is really a very fun thing. We welcome you to come to our shop to watch the actual situation (of course, business considerations are certain, don't be surprised) . Or, when our company's next round of Quick-Bending technology exhibition, you can come and visit the teachings together (the date will come soon. If you have the heart, you shall know how to let us know).

In the continuous photos in Fig. 2-4, we can see how our digital processing machine tames this 5" long pipe and domesticates a hard steel pipe into pipebends. Of course, this is only before the pipeline is prefabricated. In the paragraph, there are processes such as length cutting, ring chamfering, painting, etc. (for the piping industry, these are not hard work). In the future, we will add more elaborate and complicated processes, it also includes digital data link integration, sales channel integration (headquarters type), etc., making this technology even more visible.

Here, we still have to blow a little bit about the results of the DH Quick-Bending. In Fig. 2-5, you can see that this 5" long pipe has a total of 4 bends. If you use traditional elbow, there are 8 ring-welds (marked numbers 1-8 in the Fig. Each elbow have 2 ring-welds. It costs about 1.5 to 2.5 man-days of welders and materials. Basically, these 4 pipebends spent only 1 to 2 minutes of time on the digital processing machine. No welding consumables, no undercuts, no inspection, no cutting/grinding/noise, just few man-made, and 100% yield.

Simple, complete, smooth, no idiot, perfect industrial work.

Is the period insufficient ? Think about it.
Is the budget insufficient? Think about it.
Need high quality? Think about it.

You may change to laugh later. If you insist the ancient crafts of the last century, you may be crying later.

Fig. 2-5: DH Quick-Bending results (4 continuous pipebends, in 3D)

Of course, we also have to mention that there will still be defective products in the Quick-Bending. Fig. 2-6 shows that in the case of improper operation, the wall wrinkles appear at the elbow, and the visible continuous unevenness can be seen. These wall wrinkles can't be leveled by hand or machine. Even if they spend ten times the effort, they are not beautiful; so there is only one result: scrapping. The cost of material consumption will be absorbed by us (the processor), which is why we will require the material supplier to provide a certain margin for spare material processing.

Perfection is difficult to achieve every day, it would be a bit demanding. To expose this shortcoming, it is also to let our customers understand and accept: the machine is not omnipotent. This is also the reason why the DH Quick-Bending can achieve 100% yield in the factory inspection. As long as it is visually or hand-touched, it can detect the idiots without seemingly using instruments. When we look at many electronic technology factories, we will all know how high the yield is. In fact, we will eliminate the defective products one step at a time. In the DH Quick-Bending, we also eliminate the defective products before the factory inspection.

In the lower of Fig. 2-6, on the right side of the wall wrinkles we can see a lot of slight dents along the circumference of the straight pipe, which is the guide mold clamp used in the bending machine. The straight pipe section assists in guiding the grip caused by the forming. These light marks disappear after the bends enter the polishing/blasting and painting, as shown in the smooth pipe surface shown in Fig. 2-7. The reader does not have to care.

Fig. 2-6: Defective products of the pipebend - wall wrinkles

(4) Finished pipebends:

In Fig. 2-7, the finished product of the DH Quick-Bending after polishing can be seen. It’s quite beautiful. It’s hard to reach for weld parts (it is simply impossible).

　
Fig. 2-7: Finished product after bending

3. The comparison between DH Quick-Bending and traditional elbow

Here, the lack of the traditional pipeline we are going to talk about will be limited to the lack of the inner wall of the pipeline, and will not be discussed everything detailly, resulting in out of focus. We will first look at the actual case of traditional pipelines (this will be very similar to the section report on medical surgery).

3.1 The lack of traditional pipelines

Let's take a look at a section of the pipeline:

Fig. 3-1: Inner wall weld bead of a section of old pipe (including elbow)

Generally, when we look at the pipeline, we will give priority to the appearance of the pipeline, and we will rarely notice the inner wall surface of the pipeline (probably reason: it is not visible). The continuous photo in Fig. 3-1 shows the inner wall weld of a section of old pipe demolition (including elbows) (still fresh, we will not use the too old pipeline to show to the reader). Let me first explain that the pipeline material is 4” sch.10s SS304 90-degree elbow. The appearance of the pipeline does not seem to have too much rust, because of the SUS material; if it is an ordinary carbon steel pipe, it is necessary to look at the use of the unit daily to do the maintenance and maintenance responsibility, simply speaking, there is paint. In the middle of the top left picture, the elbow ring weld is still very obvious. Welding, grinding and painting can keep the body quite well.

Looking down, there are two obvious points on the inner wall of the pipeline:

(1) There are obvious traces of oxidation (corrosion) in the vicinity of the ring weld, but there are significantly fewer other parts outside the ring weld

In traditional elbow construction, the ring-welding is used to combine the elbow and the pipe. The high temperature (hundreds of degrees Celsius, depending on the material and welding method) and the welding rod (intermediate material) must be used to combine the two to form piping system components. The high temperature of several hundred degrees Celsius affects the material change of the pipeline material, and also causes a large residual stress, which makes the stress concentration. Once the original pipe is destroyed by high temperature, it will accelerate deterioration. (See Fig. 3-3).

In the general piping construction site, there is no long rolling line with sufficient cool down facilities like the steel pipe rolling plant, which can reduce the residual stress by annealing. In addition, if the material of the electrode is different from that of the pipeline, it will be preferentially oxidized (as the case may be), which is one of the reasons for the corrosion of the weld bead in these ring-welds. This pipe is made of stainless steel (SS304), so the corrosion (oxidation) of the undamaged part is not obvious; if it is a general black iron pipe (carbon steel pipe) material (such as ASTM A106), the part near the ring-weld , you can see more than ten times the rust state.

However, the corrosion problem is not the focus of this article, and I will leave it to be further explained later. (I will find a black iron pipe that will corrode later for a case review).

(2) There are raised weld material on the ring weld:

In Fig. 3-1, it can be observed that the inner wall of the elbow ring-weld has obvious protrusions (circular around the pipe wall), which is in the elbow when the pipeline is constructed and the indirect welding between the straight pipes is inevitable. The weld bead is chamfered along the edge of the pipe to carry out the weld bead residue caused by the full penetration and bottoming welding, and infiltrates into the inner wall surface of the pipeline. Usually this means that the original piping construction is acceptable (other variables are still available).

These underlying weld bead protrusions may be as high as 3 to 5 mm in height and may be neat or irregular (larger depending on the gap tolerance at the joint of the elbow, and of course also related to the welder's ability), due to It is located inside the pipeline and cannot be removed (for example, ground), nor can it be directly inspected by the naked eye. If it is non-destructive inspection, it is often checked whether the weld bead meets the requirements, not the protrusion.

For the flow of the pipeline contents fluid, these weld bead protrusions are regarded as unhelpful. Its presence will cause the inner diameter of the pipeline to decrease (the flow area is reduced) and the roughness to increase (the friction coefficient increases). Each bump causes a pressure loss of the fluid. Originally, in the pipeline fluid flow, the straight line segment has the smallest frictional force (exclude the special inner pipe lining, etc.), especially the smooth straight line segment is smaller, and the elbow itself is a source of pressure loss. The fluid changes direction and may change from laminar pipe flow to turbulent pipe flow. (turbulent flow increases the pressure loss. Generally, the laminar flow will become turbulent through the elbow, which will restored to the laminar flow again when pass through about 5D in length after the elbow). If a ring-weld is provided at each end of the elbow and there is a bead protrusion, which means that the pipe diameter is retracted, of course, the fluid pressure loss is increased. The surface of the pipe wall of the old pipeline may become rougher due to rust or dirt deposition, so the friction coefficient of the old pipe will be greater than the friction system of the new pipe.

For example, the continuous 4-bends shown in Fig. 2-5, in the traditional elbow pipe construction method, if each ring-weld has a bead protrusion with a height of 5 mm, it seems that it is not large, but may cause 1 %~2% of the pressure loss (depending on the pipe diameter, material, process, etc., a lot of variables), it will increase the pressure loss by 8% to 16%; if there are more than one elbow, the pressure loss will be higher. It is easy to understand for engineers who are familiar with the operation practices of the plant. These pressure losses will cause negative impacts such as increased equipment capacity (such as, using larger pumps) and increased energy consumption in the short term. In the long term, pipeline system performance will decrease and maintenance work will increase negative effects such as increased security risks.

Sometimes, the gap between elbow and pipe is sometimes large, so the welding of the ring-weld will be very large, and the material damage of the pipe will be correspondingly large. That’s most important thing of discussion in this article. The protrusions of the ring welds are also large, as shown in Fig. 3-2, which is sometimes surprisingly large. It is specifically stated here that the above-mentioned situation occurs mostly in the welding construction of the site installation. Generally, it is rare when the factory pipeline is prefabricated, and the joint is usually very close and flat. But it is not entirely impossible. This example is for illustrative purposes only.

However, the bead projections(inner) of these ring-welds are almost impossible to remove, and the reduction of system performance is also inevitable. This is the focus of this article.

Fig. 3-2: The gap between elbow and pipe is sometimes large

Take the road traffic of daily life as an example: the traffic flow on the ordinary straight road is the most stable. When the corner is encountered, the traffic flow and the speed will slow down. If it is continuous cured roads, it will be lowered. Why? This is a bit like the laminar- turbulence flow. The "elbow" and "continuous elbow" in the pipeline system are a bit like this.

The thing we often encounter when driving is that there are occasional obstacles on the road. Smaller (or softer) can be passed directly, if it is hard (such as roadblocks , broken tires, etc.), too impulsive to pass will be dangerous, naturally we will slow down. This is a bit like the "bump of elbow ring-weld" in the pipeline system. Q=V*A, when the "circulation area necking" is encountered, the flow rate is naturally reduced, the flow rate is lowered, and the pressure loss is generated.

Both of these are processes that are often used in pipelines (traditional piping methods), which have shortcomings but no solution. In the elbow of the pipeline, it is already "decelerating". The projection of the ring-weld is more "decelerating", but the factory pipeline is responsible for some production tasks, and does not allow the "deceleration" to occur. Consumption, increased pump capacity, and sufficient flow, otherwise many devices (such as heat exchangers, reactors, etc.) will be pinned to each other, causing process down. Under the request, the flow rate and flow speed of the contents of the pipeline must be maintained constant, and the fluid impacts the "ring-weld bead" day and night, which also causes the deterioration of the ring-weld. In the petrochemical plant practice, the damage rate of the pipeline system is up to the flange joint, followed by the elbow ring weld, and the straight pipe part has the lowest damage rate.

In Fig. 3-3, the damage to the weld portion of elbow ring-weld can be seen. These damages will directly cause the maintenance load of the factory (increased costs, extended downtime), and more importantly, increase the risk of plant operation. If it is a high-risk, high-explosive, highly polluting, highly toxic plant, the risk is even higher.

　
Fig. 3-3: Pipe elbow ring-weld is extremely easy to damage, perforation leakage

3.2 DH Quick-Bending improvement advantages

Looking at the finished bend shown in Fig. 2-7, we usually only see the smooth appearance of the bend, but ignore the more important smooth inner wall of the bend. No welding, no welds, no projections are the characteristics of DH Quick-Bending technology. This feature comes from the process of cold bending, directly bending the straight pipe into pipebend on the bending machine. The pipe is integrated with the elbow, and the continuous elbow is more effective.

(1) Smoother inner wall surface:

Of course, the cold-worked pipebend of DH Quick-Bending will form a smoother inner wall surface (compared to the traditional elbow ring-welding), and the direct benefit is to reduce the pressure loss of the fluid flow of the pipeline contents, so that the pipeline The system is more efficient. On the other hand, long-term and short-term benefits will be better.

The working principle of the cold-worked pipebend is that the welding is not used, and the material of straight pipe is directly used for bending and forming. Thanks to the rapid advancement of modern digital technology and the development of the machinery industry, DH Quick-Bending is more precise and easy to use. In Fig. 3-4, you can see the slice cut from the finished bent pipe produced by the DH Quick-Bending (Note: This is for the purpose of thickness measurement of the curved pipe wall, just fit to the discussion of this case, the visual inspection of the inner wall of the elbow is smooth and there is no obstruction. The flow of the pipeline contents fluid in the DH Quick-Bending pipebends should be able to exert the lowest pressure loss (the elbow pressure loss is unavoidable, but should be reduced as much as possible). And the process requirements, pipeline maintenance, and risk management can be provide the greatest help.

Fig. 3-4: DH Quick-Bending section, smooth inner wall, no protrusion obstruction
(The slight circular mark seen on the elbow and straight pipe interface is the indentation of the elbow fixture)

(2) Smoother continuous bends (multiple bends):

DH Quick-Bending With the modern large-scale digital pipe processing machine, the same steel pipe can be continuously bent into a multi-bend type. This continuous elbow configuration will reduce the pressure loss when the pipeline contents flow (compared to traditional elbow ring-welds).

In Fig. 3-5, the DH Quick-Bending can make steel pipe of the industrial grade into a smooth continuous multi-bend pipe according to the design requirements.

In Fig. 3-6, the DH Quick-bending can be made into a more fancy continuous multi-bend.

In Fig. 3-7, the DH Quick-bending can be used to make a variety of bends or continuous bends.

As show above, it just to let the reader understand the diversity of DH Quick-Bending process. It is not necessary to say that it is not only a commonly formed to a 90-degree angle, but also can be easily formed by other specific angles (such as 45∘, 60∘, etc.).

　
Fig. 3-5: DH Quick-Bending can make smooth continuous multi-bend

Fig. 3-6: Continuous multi-bend pipe that can be made by DH Quick-Bending

Fig. 3-7: DH Quick-Bending can make kinds of bends

4. summary

Four industrial revolutions: The first industrial revolution used the power of water and steam as a power source to break through the limitations of manpower and animal power in the past. The second industrial revolution used electricity to provide power and support for mass production, and also produced machinery. The goal of the machine, the third industrial revolution is the use of electronic devices and information technology (IT) to eliminate the human influence to enhance the precision and automation of industrial manufacturing. The core vocabulary of Industry 4.0 is a smart integrated sensory system that is highly automated and can proactively eliminate production barriers. [1]

Industrial piping is produced in response to industrial production needs. It is widely used in the petrochemical industry, energy industry, steel industry, and even military industry. Although the technology continues to advance, the piping industry seems to remain in the "second industrial revolution" stage, the simple judgment indicator is "still using a large amount of labor to participate in production operations."

As the times continue to advance, the piping industry has gradually entered the 3D state (3d jobs mean: dirty, dangerous, difficult job), the mentality of workers is constantly updated, today workers also gradually aging, young people do not like to join in piping work.

The appearance of the DH Quick-Bending is an attempt to push the piping industry to a more advanced third industrial revolution, which is "Industry 4.0". In addition to reducing production costs, shortening the construction period and improving quality, DH Quick-Bending has introduced advanced concepts such as digital precision production and 24HR production [2][3], and further extended; in the discussion of this article, we can see It can reduce the maintenance cost of the factory, improve the stability/efficiency of the process capacity, and even lower the operating/management risk.

References:

[1] Wikipedia (inquiries from 2017-10-07), "https://en.wikipedia.org/wiki/Industry 4.0".
[2] Lee Shengnan (2017), “High Security Review of DH Quick-Bending”, Dehan's official website, Taiwan.
[3] Lee Shengnan (2017), “Introduction to Quick-Heavy-Cold-Pipe-Bending Technology”, Dehan's official website, Taiwan.

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Production Factory: Yng Zhang Industry Co. – Web , Facebook

Postscript:

For the industrial piping industry, DH Quick-Bending is a new method. In this case, one of the laboratory pipelines was used as an example to briefly explain the high fluency of the DH Quick-Bending. In contrast to the high safety review of the previous section of the DH Quick-Bending, this case combines with the two aspects of the excellent external and internal properties of the Quick-Bending pipe (compared to the traditional elbow ring-welding method), I believe that the experienced engineers can easily understand. (update@ 2017-10-13)
In the following several exhibitions, we received questions from customers and asked about the fluidity of fluids in the pipeline. Here we have taken several pipeline slice photos to further illustrate the excellent fluidity of the Quick-Bending. These photos are mainly cut directly from the existing pipeline (SUS, stainless steel pipe _4" sch.10) along the weld-ring (the difference can be shown here most). Not much explanation, the reader relies on actual photo interpretation. (upd.@ 2018-11-09)

Fig. A-2-1: Stainless steel pipe 4" sch.10 section at the ring-weld (note the welding material inside the pipe)

Fig. A-2-2: Quick-Bending pipe (smooth inside the pipe wall as smooth as the exterior)

Fig. A-2-3：Quick-Bending pipe slice ( 5" sch.10 SUS)

B1 - Case Study (2) - High Security Review of Quick-Bending

Fri, 25 Jun 2021 21:51:12 +0800

Case Study (2) - High Security Review of Quick-Bending

Lee Shengnan / Deputy General Manager of Dehan Intellectual Technology Co., Ltd.
date : 2017-09-09

Note: The readers shall know that most content of this paper is translated from original traditional chinese version by software.

Foreword

This article will explore the implementation effectiveness and high-security review of Dehan's "Quick-Heavy-Cold-Pipe-Bending" technology (hereinafter referred to as "Quick-Bending") through a recent implementation case of a petroleum industry factory. The traditional industrial piping construction uses a lot of manpower. Quick-Bending uses a large-scale digital processing machine developed by modern technology to carry out a large number of improved elbow joints to reduce costs, save time, Improve quality, reduce product inspection load, reduce future maintenance, and improve plant operation safety.

Keywords: quick-heavy-cold-pipe-bending, Quick-Bending, dehan

1. Cae description

Construction site: Kaohsiung City, industrial zone, petroleum gas industry factory.
Construction classification: factory outdoor operation area, with flammable, high explosion, high risk.
Engineering nature: maintenance.
Special requirements: The construction period strives for minimization and the safety of the fire is extremely important.
Use technology: traditional elbow welding is used at the junction with the existing pipeline; the new pipeline is Quick-Bending.

2. the duration compression capacity of Quick-Bending

For the repair work of pipelines in the petrol gas plant with high explosion and high risk, it has always been known for its short construction period and high safety requirements. Since the contents of the pipeline in the factory are all flammable oil gas, there is still a certain danger even if the pipeline is purged. The construction period required for pipeline repair is quite short, in order to restart the system operation in the shortest time, and the short construction period also makes it necessary to use a large number of professional welding workers to deal with a large number of pipeline welding operations.

There are three sources of DH Quick-Bending compression period (just mention a few):

(1) The cost of Quick-Bending is lower and the elbow does not have to be purchased specifically:

The elbows in the pipeline is unavoidable. Before the maintenance, the factory will purchase a large number of various elbows in advance, which will be used for the contractor's piping construction. (Because the maintenance quantity is too low and the construction period is too short, the elbow parts are generally purchased directly by the owner.) Purchasing elbows must be carried out in advance, the diameter and quantity are estimated (it will be counted first, but the omission is inevitable, and each must be chased after the material is run or borrowed), which will be required for the actual maintenance work. The amount is different, so the owner must sometimes be forced to buy more and stack in warehouse. Buy more, waste more. Buy less will be hurt. Elbows are mainly in 90-degree or other angles (usually in 45 degrees) must be cut separately, sometimes resulting in material waste.

The Quick-Bending is characterized by the direct use of "straight pipe" for bending. The angle can be selected on the digital processing machine. There is no limit to the machine. (The machine is not a panacea. It is undeniable, this is still limited, but will not affect piping work). Direct procurement, acquisition, and inventory are relatively easy, and the cost is lower. Direct use of straight pipe bending, obviously, the cost will drop a lot. Easy to get, meaning: time will also save.

(2) The cost of Quick-Bending is lower, the pipebend does not have to be specially welded:

Most of the pipes for industrial piping are composed of straight pipes and elbows (of course, such as flanges, but in an insufficient amount). Generally, the elbows are mostly in 90-degree, and the both ends are connected to straight pipes, so two ring-welded welds are required at each end of each elbow. A large petrochemical plant has reached millions of Dia-inch welds. The larger the diameter of the pipeline, the longer the weld bead of the ring; the thicker the wall thickness of the pipeline, the deeper and wider the weld bead is, that is, the more artificial and the more spent. For example, as shown in the left of Fig. 2-1, a continuous pipebend of 4-bends can save 8 manual welds of the ring-weld bead and save 4 elbows.

Fig. 2-1: Quick-Bending, this continuous bend can save 8 ring-welds (left), various angle bends (right)

Taking a 3-inch pipe (such as ASTM A106) as an example, the welding construction of each ring-weld bead includes pre-staking, cutting, chamfering, face grinding, transport, alignment (fake fixing), manual welding, Inspection of repair welding, post-weld smoothing, marking, plus necessary inspections (such as PT / RT, etc.), the use of labor is about 1.5 people (including professional welders and auxiliary workers), the time required is about 1 to 3 hours. As described above, it can be known that the costly process is complicated and the cost is high. The piping industry uses a large number of workers. For operators or managers, practical management is costly and not measurable. It is a philosophical issue to treat employees and be kind to them. Usually, the law can be easily solved. If the readers have enough levels, I believe that can feel the same.

The feature of the Quick-Bending is to directly put the "straight pipe" on the processing machine, and It takes about 5 to 30 seconds to complete the bending of a 3-inch pipe (There are also two ring ends of non-ring-weld) , as shown in Fig. 2-2. If the continuous 4-bends like the one on the left in Fig. 2-1, it will take about 2 minutes (always move or calibrate. sorry, machine is not fully automated). For a familiar friend, you probably don't have to say more: "Save time to much". Let me add a word: "Costdown too much".

Fig. 2-2: Straight pipe on the digital bending machine for cold bending
(The pipe in the photo is 4"_SCH.40S, A106)

(3) Low cost, reducing the inspection of pipebend(elbow ring joint welding):

Without the elbow, there is no ring-weld bead, and of course there is no weld inspection.

For traditional elbow welding, the weld bead inspection generally adopts the PT/RT test for non-destruction test (NDT). Due to the commissioning of a third-party inspection company, it is necessary to accumulate a certain amount of prefabricated parts to reduce the inspection time/cost of the inspector. It is often necessary to wait for a period of time for the welding work to accumulate and will be unified. Therefore, it is often seen in the prefabrication field/shop that the prefabricated or semi-finished products are stacked on the ground, which is inefficient, time-consuming, occupies, and requires more artificial finishing.

    The characteristic of Quick-Bending is that straight pipe is connected with the pipebend, and there is no welding (ring-weld), so the weld bead inspection is saved, the time is saved, and the cost is also saved. Fig. 2-3 shows the applicable pipe (partial) of the 6-inch processing machine.

    Then... How does Quick-Bending test its quality? Generally, the "thinning rate" is used to calibrate. When the "straight pipe" is bent into a "pipebend" on the processing machine, although there is a solid guide mold to protect it, the metal pipe wall will still be a little "thinned" compared with the original pipe wall thickness. You can get the "thinning rate", Fig. 2-4 shows the pipe thinning rate (partial size) after pipe is bent. When the traditional elbow is made in a processing factory, it is often bent and formed by high-frequency heating method. In fact, there is also a "thinning rate", as long as it meets the specifications.

    The Quick-Bending finished product can directly use the ultrasonic thickness measuring equipment on the side of the machine to instantly check the wall thickness, which is an almost instantaneous detection data. If necessary, it is also possible to slice the pipebend for thickness inspection (refer to Fig. 3-7).

Fig. 2-3: Quick-Bending, applicable thickness table (1/2" to 5" pipe grade)

Fig. 2-4: Quick-Bending, roundness and thinning rate

Speaking of this, let's talk about the problem of residual stress. Traditional elbows also have residual stresses during bending, but only try to reduce the residual stress by heating treatment, not without residual stress. The traditional elbow is ring-welded in the ends of elbow, and the high temperature generated by the electric welding is hundreds of degrees of high temperature to weld the elbow base metal, the straight base metal, and the welding rod, so that they are combined. It cause permanent damage to the base material. The local residual stress is really high (possibly as high as 50%), as shown in Fig. 2-5. (Note that this is the "local" residual stress, not “ALL" In the pipeline elbow ring-weld, as long as the residual stress at one point is too high, it may break from "here" in the future, which is a bit like the concentration of stress concentration.)

In Fig. 2-6, we can see that in the damage control of the actual plant operation, except for the flange joint, the most prone to the condition in the pipeline is the welded part of the elbow-pipe joint (Note: Why do the situation happened in this same place? The most vulnerable here, reasonable speculation may be the stress damage after high temperature welding or welder neglect! The factory maintenance is very high), but the elbow and straight pipe are less likely to have damage management. The operations supervisor who is familiar with the operation of the plant should be the most understandable, which is also the focus of the factory crisis management control. This is one of the purposes of our development of Quick-Bending: to reduce the incidence of pipeline damage, and to improve the safety of plant operation.

Fig. 2-5: Traditional pipe-elbow prefabrication, the ring-weld bead damage caused by high temperature

Fig. 2-6: Traditional broken pipe repair and leakage (left), and perforation leakage of the base material of the bead line (right)

The Quick-Bending mainly uses a "ductile" metal pipe (such as a straight pipe of ASTM A106) to be cold-bent into a required pipebend, and the residual stress generated is less a lot relative to the residual stress of high-temperature welding. Only in poor operation will produce non-conforming products, as shown in Fig. 2-7, these idiots can almost be visually inspected or touched by hand, and the bad supplier is absolutely unable to dodge the cover; this is the advantage of quality inspection. Almost 100% factory yield.

Fig. 2-7: Good pipebend product (left), defective product/wall wrinkles (right)

When it comes to this, I don’t seem to be talking about "time saving" or "cost saving"? Or it should be said that "save both of above".

For the above information, readers can find further application information in the article "Introduction to Quick-Heavy-Cold-Pipe-Bending Technology" published on Dehan’s official website (www.dehantech.com) on 2017-07-01.

3. The excellent quality of DH Quick-Bending

The previous talk is about cost and time. Now let's talk about the theme by real case: "The high safety of DH Quick-Bending."

Fig. 3-1: Micro-damage of the pipeline in this case, temporary leakage (traditional ring-welding)

In Fig. 3-1 is a picture of the micro-damage of the pipeline in this case, where the leaking gas is found in the pipeline (new repair completed), and a photo of the temporary leak is taken. This is the transfer line of a petrol gas plant storage station. The contents of the pipeline are flammable and explosive pressured gas. The department has just completed the maintenance work (which was contracted by our partner company), and carried out the necessary inspections and inspections on the completion of each pipeline work before handing over to the owner. However, in the safety inspection after the operation of the factory, it was found that there was leakage gas in the pipeline, and the flow reading was abnormal. It was only one and one pipeline that was gradually checked one by one. It took a lot of work to find the leak point. Temporarily fixed with a sling and a hand clamp. Immediately after the repair work, it is a risk warfare competition, with three N₂ blowing drive, auxiliary safety, and then dare to repair the repair on site.

I want to come afterwards. It’s really a "frightening". The piping work is really "dangerous work ". I believe that the owner's personnel are also afraid of death. If you wait until a certain period of time (such as the warranty period has passed), the life and health of the factory operators and your job may have problems. This dangerous leakage situation occurs in all factories and all pipeline contractors, and it has happened. Some factories still perform (may be due to too large factories, too many factories, unfamiliar operations, or in-line fluid specificity, can not be said in a word. Most of them are classified as mechanical abnormalities afterwards, everyone is not responsible). As long as it happens once, the factory will be in trouble. The protests outside the factory are constant, the administrative punishment is heavy now, and sometimes it is difficult to get rid of crimes in the administration of justice. It is best not to happen as well.

In fact, the welders assigned to the welding work has experience for more than a decade, can not be said to be inexperienced, but there are still some regrets. If there is a gas explosion, it may be a catastrophe. The contractor can’t pay for it, and it hurts a lot of nearby residents. (Because the land is narrow, Taiwan’s industrial area is almost adjacent to the residential area, and the safety impact cannot be avoided) The threat to the manager level of the factory is also very large, especially the current legal requirements, penalties and fines are higher, let alone the environmental resistance of the residents / environment protect group. In our experience, this similar situation has occurred in other factories. The petrochemical plant is classified as a high-risk site and is strictly guarded. It is not without cause.

In fact, due to various manpower problems in Taiwan, including young people who are less willing to take up hard/dangerous welding work, the investment of petrochemical industry has gradually shrunk, resulting in insufficiently stable handling of the work in the piping industry, affecting the employment of personnel, etc. The most of workers in the piping industry are also aging more than 45. All the old welders can be left behind (for the sake of life, and for the family). Many of the people on the scene are gray-haired middle-aged employees. (When the workload is small, it is okay, and the workload is large, it is easy to appear. This is a problem in the connection of manpower. The piping project is not like the construction industry, it can be easily filled by people, and only local welders can be used. This paragraph explains: the manpower predicament under the long-term management of the piping industry, it is necessary to replace some of the manpower with mechanization, in order to achieve high value of the enterprise, and also let young people are willing to come to work.)

Afterwards, we re-do an improved review. The use of professional welders, careful welding operations, solid pipeline materials and welding rods, item by item inspections, etc., are our daily cautious, very regular, very customary work requirements, welders are also very duty-abiding, weld bead also check one by one, why is there still a gas leak problem?

(1) Manual welding is not 100% exempt from welding:

Professional welders are highly trained welders who can minimize the incidence of welding work errors, but cannot be completely eliminated. After all, people are not gods, and professional welders are still human.

The following factors will affect the quality of the finished welding products: the physical load of the professional welder (including long working hours, overtime, staying up late, etc.), mood/mental state at work, and poor workplace environment at the construction site (prefabrication shop may be better) , weather (wind/rain), auxiliary tools, support personnel, etc., even the wife quarreling, the boss does not pay a salary, etc., may be the cause of the error. It can be seen in Fig. 2-5 that the welding work is a hard physical activity. These negative influencing factors, once caused by the insults on the weld bead (such as micro-cracks, weld bead defects, etc.), can cause a large casualty disaster.

It is conceivable that every 1,000 meters of welding, as long as there is one mistake, it may cause major work safety / public security casualties; of course, it is necessary to try to prevent such mistakes as much as possible, at least, to be as low as possible the incidence of mistakes.

In this case, we used the DH Quick-Bending to make other new pipebends(elbows), and there was no leakage. For example, Fig. 3-2 shows the other pipes in the case. In the middle of the pipeline, the DH Quick-Bending is used at marked points 1/2, and the traditional ring-weld is at marked points 3/4 (because it is to be flanged or three-way joint), the marked point 5 on the right is a longer multiple continuous bend. We can see that the DH Quick-Bending at marked points 1/2/5 is completely non-contact smooth (not artificially ground). When we finished, we obviously saw the owner's appreciative appreciation of the expression, not just safety. It also contains the graceful and elegant curves of an industrial-grade work (the people of engineering, the view is relatively simple, the beauty is beautiful, there is no modifier auxiliary). I believe that if you are an expert, you should understand.

Fig. 3-2: Piping in this case - single pipebend (marked points 1/2/5 for DH Quick-Bending, 3/4 for traditional ring-weld)

In Fig. 3-3, it is the case of a continuous elbow using the DH Quick-Bending in the same case. The contractor's boss should see the saved cost of the 4 ring-welds marked points 1/2/3/4. We are seeing the time/cost that can be saved, allowing us to use less welding manpower, especially in the era when this professional welder is not easy to find, train, and retain, can operate in a semi-automatic mechanized way of larger, more precise piping capacity.

As shown in Fig. 3-4, it is the case of the pipe row using the DH Quick-Bending in the same case. The same pipe diameter/bending diameter/shape can be used to realize the Quick-Bending process and can also use the “Copy” Command, the Quick-Bending can do it.

Fig. 3-3: Piping in case - continuous bends (DH Quick-Bending)

Fig. 3-4: Piping in case - Pipe row (DH Quick-Bending)

In theory, the DH Quick-Bending machine can work 24 hours, computer controlled digital operation, high precision, so that you can see the big difference with the traditional piping method.
In addition to the bending process, we have developed them to produce other higher value-added products and services (to introduce the franchise system headquarters plan, automation plant, etc.).

(2) The inspection cannot be 100% detected by welding:

Inspection is the only way to verify the quality of the finished product.

In traditional piping construction, elbows are purchased from processing factories or traders. Basically, there are signs and models marked on them, and there is no need for testing (it is not clear whether there is any insult). Straight pipe is a large amount of material, and there is no need for inspection (the pipe factory is a big factory, there should be no idiots, otherwise the pipe factory may not survive in this industry). The main inspection point of the finished product is the ring-weld bead at the interface the elbow and the straight pipe. Generally, the PT/RT test is adopted, it is inspected by a third-party company. The test has a certain proportion of sample sampling rate, but it is a little difficult to reach 100% (due to cost and duration).

The DH Quick-Bending is a type of cold-bending pipe. After bending by the processing machine, the thickness reduction of the finished pipebend wall can be directly measured by the "ultrasonic thickness gauge" (non-destructive test). There are a variety of brands available in the market for ultrasonic thickness gauges made from European, American, Japan, China and Taiwan are quite popular. The price ranges from NT$10,000 to NT$100,000, and it is very easy to obtain. As shown in Fig. 3-6, several ultrasonic thickness gauges available in the Taiwan market are available for reference (note: the data is randomly searched from the internet). The owner or the client can inspected the pipebend product through a third-party company, or they can test by their own equipment anytime, anywhere. The pipebends produced in our own factory shall be qualified for the customer before leaving the factory to ensure that the quality of the finished pipebend is strictly controlled; if the customer requests, it can also be tested 100% (in the business, the price is linked to the service requirements).

Fig. 3-6: Several Ultrasonic Thickness Gages on the Market
(Source: websites of Chuan Hua Precision Co. and YENSTRON Co.)

Fig. 3-7: Pipebend slicing, ready for wall thickness measurement (minimum at the center of the pipebend)

The customer can also request a slice inspection (destructive test), cut the pipebend piece for thickness measurement, as shown in Fig. 3-7. However, this method is complicated, time consuming, and costly. To progress the "Ultrasonic Thickness Gauge" instruments have been available, the cost is small, and is very convenient, the personnel is easy to operate, through various international standards certification (such as ASTM E 797, EN15317, etc.), data trust is enough. We recommend using the instrument directly, it is not necessary to return to the Stone Age!

Low-cost, fast, accurate, digital, environmentally friendly, no consumables, ready to go anywhere and anytime, no waste in floating time is a feature of rapid inspection. You can even connect the computer to the massive data processing operation in the back stage, shape the life history and trustworthiness of the finished product of pipebend, and help the quality of the parts, which is extremely suitable for the high-tech or biotechnology industry with high requirements.

This section is mainly to describe how the inspection of the Quick-Bending can catch up with the requirements of the times and make an auxiliary narrative.

4. Conclusions and recommendations

I don’t have great conclusions and suggestions, just talk about it casually.

For traditional industrial piping construction, DH Quick-Bending is a new technology. Ever, new technologies would encounter many blocks from old market, attacked, and crowded out. This has always happened. It is not only the simplicity of technology, but also the change of the existing market and the defense of the industry. It is inevitable that the two forces will advance and consolidate.

But the history of industrial development and human history also tell us about some facts that have happened and are happening:

The replacement of old technology by new technologies is inevitable; the change of traditional cognition is only a matter of time.

This article introduces the facts of the actual case, and compares the DH Quick-Bending with the traditional elbow to find a better level of technical application. In this case, the traditional elbow ring-weld is a manual welder (slow work, fine grinding) that has been used by professional welders for decades. While the DH Quick-Bending uses the latest technology products – large digital bend machines that is used to bend the straight pipe into a pipebend (rapid forming). There is indeed a great deal of commercial thinking difference of the manpower, machine, material, working method, thought, inspection, safety considerations, durability, construction speed, or even the cost and profit of the market.

Previous pipe benders were only simple bends, and only thin pipes, such as common stainless handrails; simply speaking, "bending the pipe". In the field of industrial piping, it must be resistant to high temperature, high pressure, special contents (such as corrosive, toxic, diffusive, polluting, flammable, or high-explosive, etc., quite dangerous). High pipeline material requirements, pipe wall thickness is also much thicker, and the existing pipe bending machine cannot be overcome. Nowadays, the large-scale pipebend processing machine has been developed with a larger output, a thicker bendable wall, a larger outer diameter of the pipe, and a smaller bendable radius (the traditional bend can only reach 3DR, and the DH Quick-Bending can be used for 1DR to 1.5DR), the guided mold is more complex and precise, and can be applied to industrial piping. And with Taiwan's strengths: computer hardware capabilities, to make the pipebend digitized, automatic control, and even a large amount of data processing, resulting in better efficiency and greater productivity.

The use of automated machinery production, replacing traditional manual production, is a "world trend" that can’t be resist by you and I.

In 2012, the industrial powerful nation Germany proposed the "Industry 4.0" blueprint, the United States in 2014 - "AMP" (Advanced Manufacturing Partnership), Korea in 2014 - "Manufacturing Innovation 3.0", even China It also announced the launch of "China Manufacturing 2025", which is aimed at bring the national industrial production to a high-speed track that is intelligent, automated and highly standardized.

Taiwan is talking about "productivity 4.0". The tone is high, but it seems to be a bit of action. The industrial piping industry is a mass production industry that consumes a lot of labor. Although it is not completely automated, it can be achieved with a degree of semi-automation. Dehan's Quick-Bending is moving toward this goal, and we hope that someday the piping industry can truly "productivity 4.0." Dehan's technology is not inferior to the world's powers.

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(Note: There may be some differences between the text and the web version)

Technical inquiry:

Email: service@dehantech.com
Production Factory: Ying Zhang Industry Co. – Web , Facebook

Postscript:

1. This short text is written for the review of the occurrence of micro-damage in the elbow ring-weld bead of petrochemical pipelines and to prevent future hidden dangers.

2. Originally, this is just a very ordinary pipeline repair case. The professional welder with more than ten years of experience is very familiar. It is a pleasant and pleasant job for a professional piping company with more than 40 years of work experience. However, the leaked leaks discovered afterwards made the whole case a bit tricky. In this case, we noticed that the ring-welding of the traditional elbow is the most unstable place. The quality of the welder is of course influential. The inspection and inspection methods also have an impact, but must it be reliable? 1,000 joints, as long as there is a problem with one joint, may become a big problem on a certain day of future. (This means that as long as the welder's hand shakes a few times more, or stays for 2 seconds more, or stops to smoke, it may cause future hidden dangers. Because "manual use" is not 100% certain. thing)

The pipelines of the petrochemical industry pay great attention to safety requirements, and the characteristics of the pipeline contents are complex, and they are all pressure pipes (internal pressure). The flow of fluid in the pipeline around the clock will gradually impact (flow will have kinetic energy) and erosion (related to fluid properties), as long as there is a small defect in the entire ring-weld bead (such as broken or insufficient weld bead, or the welding material is not densely combined) Etc., the elbow ring-weld bead is the biggest weakness on the whole pipeline. Under the long-term effect, it will gradually expand a small hole into a large hole that can be harmed. At that time, the disaster will disappear and burst at any time. (especially when the contents of the pipeline are flammable or explosive, as in this case), "water can penetrate the stone" is a similar principle. Many of the sudden disasters in petrochemical plants may come from such hidden dangers.

So we must prevent this problem. The method is "reducing the bead weld bead of the elbow". Of course, it is better not to use the bead weld bead at all (disappearance is impossible, and reduction is a pragmatic prescription). In the case, we also used the DH uick-Bending pipebend, which was just used for review. Basically, that is the way to not use the elbow ring-weld bead. In one case, if you want to use 1,000 ring-weld beads, if you can reduce the amount of 2/3 or more, not only the cost reduction, the shortening of the construction period, but also the positive value for the completion inspection, daily operation inspection, and safety maintenance. Practice.

In the past, due to the lack of energy of the bend processing machine, the requirements of the petrochemical pipeline could not be met, and the elbow could only be handled according to the traditional manual welding method. Nowadays, large-scale pipe bending machine has been developed in Taiwan, mainly for heavy-duty pipelines (thick pipes), which can fully meet the needs of petrochemical pipelines. With the help of the direct bend function, the number of ring-weld beads can be reduced to improve the future disaster prevention effect and reduce the hidden danger of pipe breaking. It is believed that the crisis control of the plant operation is greatly helpful. Of course, pipelines with too large diameters are unlikely to be included in the recent development of processing machines due to the low demand (commercial society, do-it-yourself, and quantity only organic). At present, the development of the digital pipebend processing machine has reached 12" pipes in energy, and is still mainly based on 6" pipes. (upd.@2017-09-12)

B1: Brief Introduction to Quick-Heavy-Cold-Pipe-Bending Technology

Fri, 25 Jun 2021 21:51:12 +0800

Brief Introduction to DH Quick-Heavy-Cold-Pipe-Bend Technology
Lee Shengnan / Deputy General Manager of Dehan Intellectual Technology Co., Ltd.
date: 2017-07-01

Note: The readers shall know that traditional version is original, most content of this paper was translated from it by software.

Forword
Metal piping is widely used in various industrial constructions, such as petrochemical industry, steel industry, electronics industry, shipbuilding and so on. The piping of steel pipelines is the most common, and the main components are divided into straight pipes, elbows, and valves ,etc. Straight pipes and elbows are made of steel pipes of specifications (outer diameter, pipe thickness, etc.), occupying the vast majority of piping work. The straight pipe and the elbow must be welded together to ensure the joint quality.

The overall cost of the piping, in addition to the cost of the pipe, also includes welding manpower/machine tools/materials/inspection, etc. The process is complex, and the relative cost is high and the construction is slow. How to reduce the cost of piping, and effectively improve the quality of finished piping, shorten the installation speed of pipelines, and meet the requirements of rapid construction, that is, the main improvement goal of the next generation of piping construction/engineering. The scope of this paper is mainly based on petrochemical plant pipelines, and other industrial pipelines.

Keywords: quick-heavy-cold-bending, quick bending, dehan, elbow, pipe bending

1. The traditional piping construction methods - advantages & disadvantages

The main features of heavy-duty pipelines in petrochemical plants are high internal pressure, high wall thickness, high material strength, and high danger of the contents of the pipeline. Therefore, it is impossible to take joints with the thread and must be welded. In this paper, the general discussion is mainly based on petrochemical plant pipelines. Other industrial pipelines are of course applicable, even the small pressure inside the pipeline.

The piping is generally classified as an installation work at the construction site. In addition to valves, flanges and supports, the materials are mainly two types of pipes and elbows. Of course, insulation and instrumentation are not included here. As the length of the pipe is longer or the elbows is more, the consumption of the straight pipe and the elbow is more, the more the welding, the longer the time required, and the more the number of inspections.

1.1 Main items of piping work

In the work of piping, the main work items are three sub-items of material procurement, pipeline prefabrication (in prefabrication plant or contractor’s shop), site installation.

Material procurement => Pipeline prefabrication => Site Installation

These three major items should take a lot of time and cost. In this paper, we will discuss the pipelines that can be purchased from the engineering market are generally used ,and exclude the special material/diameter pipelines. In the site installation, the expected ratio of pipeline prefabrication to on-site installation is about 6:4 to 7:3, depending on the circumstances of the case, it may be lower.

The higher the proportion of pipeline prefabrication work, the lower the workload on the site, and usually means that the work will be faster and smoother. The pipeline prefabrication work is carried out in the contractor's shop/factory. The working environment in the factory is relatively stable, and it is less subject to weather disturbance. The operating tools are more complete (such as cranes, stackers, welders, wheel cutters, straighteners, etc.). The labor utilization rate and production efficiency are also high, and it is easy to command. Generally, the quality of pipeline prefabrication is higher than the quality of on-site installation, and it is easy to inspect and overhaul. Owners and supervisors also prefer pipeline prefabrication.

If the amount of pipeline prefabrication can be increased, and the quality of the prefabricated product is improved, and the cost is lowerized, the piping construction will undergo major changes.

(1) Material procurement:
    It is divided into two major categories: straight pipe and elbow.
    Straight pipe is easier in stacking and less likely to be damaged.
    When the elbow material is delivered, it has already been processed (such as bending diameter, angle, including wall chamfer/grinding, etc.). It is generally not recommended to stack it to avoid damage, so it usually requires a relatively large space to stack and storage. When large project is implemented, elbows are usually stacked everywhere in shop . If the elbow delivery sequence is not properly arranged, it will also delay the follow-up work (prefabrication or on-site work). (See Fig. 1-1)

(2) Pipeline prefabrication:
Exclude the pre-fabrication of valves or flanges, prefabrication work must use a lot of labor to measure, cut, grind, weld, grind, and the latter part of the testing, including RT / NDT, X-RAY test, etc., are necessary processes.
Take example of a set of "straight pipe + elbow" welding. In addition to the operations of transport/fake fixing/grinding, it is necessary to carry out the ring welding manually. The required welding time varies depending on the pipe diameter and wall thickness, and may be spent 0.5 hours to several hours. (Note: The pipeline material is limit to the common ASTM A53/A106, etc. for easy discussion) (see Fig. 1-2)

(3) Installation and construction:
    The prefabricated pipeline parts of straight pipe & elbow materials carried to the construction site, and assembled thems.
    Unlike pipeline prefabrication work in prefabricated yards/factories, pipeline parts can be overturned by machine/manpower and fully processed at all angles. On-site pipeline installation and assembly work in site is often limited by facility location, angle, and situation of work platform ,etc., will result in great quality differences in each installed product. (See Fig. 1-3)
    Most importantly, sometimes the welder cannot properly perform the installation because of the space limitations or angles of the mounting points, which may result in the welding quality being inadvertent and sometimes impossible to test. In addition to delaying the speed of installation work, after completion, the pipeline contents are constantly flowing, which is particularly prone to rust at some poor quality solder joints, resulting in an increase in future maintenance work (year-old repair or temporary repair). Increase costs. In addition, these shortcomings are extremely prone to sudden unexpected events, damage to human life and loss of property (see Fig. 1-4).

Fig. 1-1: Traditional elbow material (when the quantity is large, it will pile up everywhere)

Fig. 1-2: Prefabrication of pipelines in traditional contractor’s factory (still relying heavily on professional welders/labors)

Fig. 1-3: Fake fixing method used in traditional installation(site) elbow/pipe (the inner weld bead often has internal defects and residual stress)

Fig. 1-4: traditional site breakage repair and leakage (left) and
perforation leakage of the parent material of the bead line (right)

1.2 Missing of various sub-items of piping work

In the implementation of piping work, the main sub-items still have the following shortcomings for discussion:

(1) Material procurement:
In addition to valves, the main purchases are straight pipe and elbow.

(i) Straight pipes and elbows should be purchased separately:

Since most straight pipes are ordered from the big dealers, the elbows must be purchased from the processors. A variety of different procurements will generate a lot of management costs and troubles.

(ii) Elbow purchases (delivery) are slower:

Materials of Straight pipe, generally are conventional products can be purchased at any time from market. The elbow is processed from the straight pipe by the processor. Except for the material purchase and transportation, in addition to the necessary processing time, the processing must be determined according to the production schedule of the processing line. If it is urgently needed and there is no stock, there are requirements for inserting orders, which is quite troublesome; when the demand for elbows is small or the specifications are special, it is more troublesome; in addition, there are processes such as replacing the processing die set. In the process of prefabrication or installation, if there is a lack of elbows (especially special specifications), it will happen if it is to be worked or replaced by other products.

(iii) Elbow delivery must be counted, space required for stacking, and sorted for easy access:

After all, the elbow material is metal, and the weight is heavier. The large-size elbow is often difficult to move by hand, and sometimes it needs to be matched with the machine. Elbow material prices are more delicate, small-size elbows are easy to be lost for the workers or outsiders, and the warehouse management must pay attention, otherwise it will cause delays in follow-up work (prefabrication or on-site).

(2) Prefabrication of pipelines:

taking "straight pipe + elbow" welding in the contractor's factory as an example:

(i) Welding work shall be carried out by labor:

Heavy-duty piping (for example, industrial piping at the petrochemical plant), as the flowing liquid or gas in the pipeline is at high pressure, the pressure inside the pipeline is very large and cannot be combined with a simple screw casing ways to transport. Industrial piping has certain risks in normal operation, so the piping welding work is particularly important. The welder must be specially trained (usually shall be certified); and the more important pipeline welding welders must often be experienced by experienced welders. Labor costs are not cheap. The use of labor, correspondingly, must have labor, health insurance, accident insurance costs, and other necessary expenses. (See Fig. 1-2)
In addition, in the case of pipeline welding with special materials (such as TI tubes, special alloy steel tubes, etc.), it is necessary to have a special training qualified professional welder to cooperate, or to perform additional commissions, and the cost is higher.

(ii) Welding work shall be carried out with electrodes:

In addition to the base metal, the welding work must have the need for welding rods, and the cost of the welding rod must exist. In the use of welding rods, manual material picking, heat preservation, and material consumption will inevitably lead to higher costs. Special material welding rods are more expensive.

(iii) Welding work must spend a lot of time:

Pipe welding time is generally related to the length of the weld bead, the thickness of the weld, and the number of weld layers. The more time. It must be related to labor costs unless automated machine tools are used. On the heavy-duty piping, all are carried out by manual welding, which is inevitable, the labor cost is high, and the construction period is long. (See Fig. 1-5)

Fig. 1-5: In traditional prefabrication, a large number of professional welders must be used

(iv) The welding work must be carried out with sufficient land or space:

Manual welding cannot be done instantaneously and stay to work for a long time. Pipe fittings are laid and the contractor's factory needs to have enough land (open-air) or shop space (indoor) to meet. If the land/space is insufficient, it must be overtime/shift work, the cost will increase, the construction period will be lengthened, and the quality will decline. (See Fig. 1-6)

Fig. 1-6: In traditional prefabrication, using a large number of plants or space

(v) The results of the welding work must be verified:

Industrial piping welding is an important task. In addition to the self-inspection of the contractor, the owner or the main contractor often has to station the factory supervisor and the inspection manpower. It must also have an outsourcing third-party inspection agency to carry out inspection procedures such as PT/RT to prevent improper quality of the construction that will cause accidents in the operation of the owner's factory in the future, and it will not be lightly responsible for major accidents. These necessary procedures will increase costs and lengthen the construction period. (See Fig. 1-7)

Fig. 1-7: A large number of X-RAY inspection procedures are required for traditional prefabrication

(3) Installation:

Carry the prefabricated parts and straight pipe/elbow materials to the construction site and install them on site.

(i) A large amount of welding work is required:

The general site installation is similar to the contractor's factory prefabrication, except that the work location is at the site. Of course, different measures are derived from the local conditions. The amount of welding on the construction site is proportional to the number of joints required for the pipeline. The fewer the joints, the less the welding amount, the lower the cost and the shorter the construction period. Of course, the quality is higher (this is why the factory prefabricated quality is better than site installation as an example).

(ii) Site welding quality may be affected by space limitations or angles:

After all, the welding of the site must be carried out manually, and the welder will be subject to multiple restrictions on the working space, human limbs and welding tools. When the angle is not good and the space is crowded, the welder's welding quality will be affected and reduced, and the completion period will be correspondingly lengthened, and the cost will increase accordingly (see Fig.1-8). This is even more evident in the piping work or maintenance work carried out in the ship's cabin.

Fig. 1-8: Pipe welding quality is controlled by narrow spaces and working environment

2. Advantages and disadvantages of the new "quick heavy cold pipe bending" technology

As mentioned above, the traditional industrial piping is still a deficiency. The newly developed "Quick Heavy Cold Pipe Bending" technology (hereinafter referred to as "quick pipe bending") is used to improve the traditional piping method to reduce costs, shorten the construction period and improve quality.

2.1 Operation principle and method of quick-heavy-cold-pipe-bending technology

Thanks to the advancement of modern technology, modern industrial piping drawings have been digitized (referring to AutoCAD drawings, or other soft-system diagrams, such as the common PDMS/PDS in Taiwan). The specific transfer to ISO drawings can also be easily used by other manufacturers/collaborative staff to read. This is a modernization of the design/drawing work, which greatly reduces manpower and improves the quality of the design/manufacturing interface.
However, on the actual construction side, including the contractor's factory prefabrication and site installation, there was no major progress, and it still remained in the use of a large number of manpower (including professional welders and other auxiliary manpower).

The development of the "quick-heavy-cold-pipe-bending" technology is to improve the old piping work method to save manpower and various costs.

The operation principle of the quick-heavy-cold-pipe-bending technology is mainly to use a large-scale hydraulic processing machine with precision (see Fig. 2-1) to directly cold-bend the straight pipe material into a pipebent of specific angle. It is still connected to the other straight pipes on front or rare point (cutting can be processed according to requirements). A length of straight pipe can be processed into a continuous composition consisting of several bents and straight pipes (see Fig. 2-2). Newly developed quick-heavy-cold-pipe-bending technology, the machine has CNC bending machine, NC bending machine, etc. It adopts professional customized manufacturing and can reach the bending processing technology of R/D=1.5 times of industrial-grade pipe long-diameter elbow.

Fig. 2-1: CNC machine for Quick-heavy-cold-pipe-bending

Fig. 2-2: finished example (continuous bent) for Quick-heavy-cold-pipe-bending

Originally, this cold-worked pipebent was used to bend small-diameter thin pipes. As modern processing tools(machines) have gradually become larger, the applicable outer diameters of the curved pipes are larger and the walls are thicker. At present, it only lists up to 5" Φ pipe diameter, and soon it can reach 10" to 12" Φ pipe diameter (see Fig. 2-3). The product is used in petrochemical plants and technology industry industrial pipeline cold bending heavy processing (carbon steel pipe, stainless steel pipe, alloy steel pipe, etc. are processed and bent.) The applicable diameter of the steel pipe is from 0.5" to 5" Φ, and the bending capacity is from 5S to XXS.

Fig. 2-3: suitable thickness table (1/2" to 5" pipe grade) for quick pipebent

In the quick bending operation, the most important thing is the roundness and thinning rate of finished products(pipebent) in the bent section (see Fig.2-4). The data under actual cold work implementation is no worse than the purchased bend requirements.

Fig. 2-4: roundness and thinning rate for Quick bent

In the production of traditional elbows, in addition to the large-diameter outer diameter elbows, the method of splicing welding (commonly known as shrimp pipe) is mainly used for heat treatment of elbows (high-frequency heating), as well as cold-working die extrusion. The method depends on the material of the pipeline and the thickness of the pipe.

Generally, the most worrying aspect in pipeline design is the problem of residual stress in the pipeline of the quick pipebent. In fact, in the traditional piping process, in addition to the residual stress remaining in the processing of the elbow material in the processing plant, the residual stress caused by the high-temperature joint of the straight pipe and the elbow joint welding is not less than the residual stress; The damage left by the welding to the pipeline body is greater, and there are more problems remaining in the maintenance and repair in the future operation, and there are more hidden dangers. Our company's quick bending technology uses large processing tools for cold bending and high precision. With high-power bending machine, high-precision and complex diameter mold, guide mold, clamping mold, and core parts, under the control of adjustable speed digital position, it is possible to bend the pipebent without welding. Under the digital control processing, the quick bend can also bend out the combination of various angles, which is beyond the reach of traditional elbow. (See Fig. 2-5)

Fig. 2-5: Quick bend, thick pipe capacity and various angles (2"_160S_SS304)

At present, general piping is also used in the form of cold-worked pipebent, but most of them are curved pipes with a curved diameter of 3DR (commonly known as a large bend). This is because the previous processing machine still has technical deficiencies, and can only bend the curved pipe with a large bending diameter, which will have a great influence on the piping space.

In the piping of petrochemical plants, due to technical requirements and space requirements, the elbows are mostly 1.5DR (commonly known as long-diameter elbows). Therefore, the traditional tool/machine of cold-bending is not suitable, and only elbow-welding can be used. Our quick bending technology utilizes the latest large processing machine, which can be used to make a straight bend with a small bend diameter of 1.5DR. The minimum can reach the bend diameter of 1DR (commonly known as short-diameter elbow) (all depending on material and pipe size. The machine is a machine, but not a panacea), which can meet the needs of petrochemical plants.

2.2 Advantages of quick-heavy-cold-pipebending technology

The appearance of a new technology mean that some existing shortcomings of the old technology can be improved, or simplified, or improved. The quick-heavy-cold-pipebending technology has the following advantages:

(1) Quick bending can save processing time:
    Traditional industrial piping "straight pipe + elbow" joints are all welded by a professional welder. The welding time varies with pipe diameter, wall thickness and pipe material. For example, in the case of the common ASTM A106 2"Φ sch.40 pipe, a ring welding process takes about 0.5 to 1.0 hours, including professional welders and auxiliary labor. Other handling, false fixing, pipe grinding and dressing, bead grinding and dressing, etc. Time is also required. In addition, it is necessary to add the time required for various types of inspections (depending on the contracting requirements). If the ends of the elbow are to be joined to the straight pipe, it takes twice as long.(see Fig. 2-6)
    The new type of quick-bending pipebent processing, as long as the straight pipe is processed on the machine, the ASTM A106 2”Φ sch.40 pipe is taken as an example. One pipebent (the bent is connected to the straight pipe at both ends) is almost It can be completed in 10 to 30 seconds. The bending process is completed, completely controlled by the program digits, and the precision is not misplaced.
    This advantage is almost a microcosm and representative of all the advantages of the new "quick-bending” technology. Other advantages, let's continue.

Fig. 2-6: Comparison of traditional piping welding and quick-bending operation (same 4” 40s CS pipe)

(2) Quick-bending can save the purchase of traditional elbows and save costs:　　
    The traditional industrial piping “elbow” must be purchased separately. Since the elbow is more expensive than the straight pipe, it will increase the cost. Moreover, the procurement delivery schedule of elbow parts will obviously be longer than the straight pipe purchase.
    Quick-bending technology directly adopts the straight pipe and pipe bending process, which can obviously save a lot of elbow costs. The direct processing of straight pipe into a curved pipebent can also reduce the loss of material of the straight pipe material, the benefit is obvious, and the speed of purchase and delivery is also fast. The material of these quick bends is the same as that of the straight pipe, and there will be no mistakes in material misconnection. Using precision machine processing, the pipebent can be directly digitally precision machined regardless of the 90°, 45° or other special angles. It is no longer necessary to cut the elbow secondary, saving cost and shortening the construction period, and improve quality.
    The quick-bending can always make the pipe into a continuous pipebents, saving processing time and materials. The traditional industrial piping is fixed in a similar way with the "straight pipe - elbow - straight pipe - elbow". It is determined that each elbow must have a ring weld at both ends, and it is also destined to waste more time and increase the cost.
    The new type of quick-bending processing can be used to continuously bend the pipe on the machine and continuously bend the pipe into several "straight pipe + elbow" type; of course, this will be limited by the size of the machine, the bending limit and the purchase straight, pipe length, etc. Standard industrial piping, especially for pipeline of multi-pipes, is usually turned in the same way as "bend and turn", so there must be multiple continuous bends on the path. The quick-bending technology can produce the required continuous bents, and the two ring-shaped joints are saved at each bent, which has obvious benefits. (See Fig. 2-7)

Fig. 2-7: Quick-bending, this continuous bents can save 8 ring-welds (left), various angle bents (right)

(3) The continuous bents of the quick-bend can stagger the joints that are not easy to weld, which can improve the quality:
The traditional industrial piping is fixed with the “straight pipe-elbow-straight pipe-elbow” parts. When it is transported to the construction site, many site contacts may be located in a space-constrained location, and the overall quality will be poor.
Quick-bending processing can use the method of continuous bending to try to stagger the places that are difficult to weld when the future construction site is installed, which can improve the quality. Also, because of the technology of continuous bending, the number of welded joints installed on the construction site is reduced, and the overall construction cost is also reduced and the construction period is shortened. This feature is especially suitable for extremely narrow spaces, such as ships and cabins that are not easily welded.

(4) The quick-bending prefabrication work can be processed for 24 hours/day:
After all, traditional industrial piping prefabrication is limited to human physical fitness, family life, lighting, weather, labor laws and regulations, and working time has its limits and restrictions.
Quick-bending processing, using modern high-tech/higt-precision processing machine, as long as the power is supplied, it can be processed for a long time with few manpower. In theory, it can work 24 hours (of course, even the best machine still need maintenance), saving time and cost. This is a shortage of manpower in the Taiwan industry today, especially in the industrial piping industry where professional welders must be employed. The quick-bending process can use least manpower for prefabrication operations with obvious benefits.

(5) The quick-bending prefabrication can be completely processed in the factory:
The prefabrication of traditional industrial piping is limited to the contractor's workplace. The outdoor construction (pre-fabrication) would be partially used, and it is also affected by some weather factor (the welding work is susceptible to rain). The quality is easy to be different.
Quick-bending processing, using high-tech/high-precision machine, can be almost completely operated in the shop, even in the rainy season, the quality stability is high, and the stability of product quality would not effected by continuous working for a long time.

(6) Quick-bending preforms stable quality:
The traditional industrial piping prefabrication stay in manual work, and the finished product will be limited by the professional welder quality of the contractor/sub-contractor. The quality of the finished product may vary depending on the quality of professional training of the welder. In addition, the contractor may be forced to temporarily adjust/dispatch, and be a veteran due to factors such as rushing work, worker mobility, and even worker resistance and labor disputes. Usually, outsourcing/re-subcontracting operations, etc., affecting quality and delivery.
Quick-bending using modern high-tech/precision machines, almost got the same finished product quality, which is the characteristics of mechanical production, although it can not reach the highest level of production of light-less, but compared with traditional production methods, it has been greatly improved.

(7) Pre-fabrication of quick-bending with less manpower, more professional training and stable quality:
Traditional industrial piping prefabrication must use a lot of manual operations. The physical load of the staff is large and the flow of personnel is large. The contractor must continuously recruit and train the welders, which is easy to have quality differences.
Quick-bending use modern high-tech/precision machines, the use of labors is almost minimized. This high-precision processing machine must be operated by professionally trained personnel. Due to the less manpower, it is easy to concentrate on training. And the working place is the indoor work(shop), the staff is stable, the mobility is low, the quality is easy to check, and the technology is easier to accumulate.

(8) Quick-bending prefabrication is centralized operation, other machines in the vicinity of the machine in the factory are complete, and the operation efficiency is higher:
    Traditional industrial piping is a manpower-concentrated work. Even if it is prefabricated at the factory, it must be deployed in a large area of land/space. Although the use of machinery (such as spreaders, stackers, etc.), the benefits are difficult to develop.
    Quick-bending processing, the main operations are concentrated in the vicinity of the processing machine, plus the use of other equipment to assist, the efficiency is obvious. Modern factory management pays attention to machinework to reduce manpower, improve efficiency, and reduce costs. This would be better with the quick-bending technology.
    Conventional industrial piping prefabrication still requires a lot of welding on joints of "straight pipe-elbow" (ring-weld). In fact, the weld of interface is the weakest point of the entire pipeline.
    Quick-bending directly bends straight pipe into curved pipe or continuous curved pipe. Without welding, the quality of finished products can be ensured. Of course, this does not mean that the quick-bending process does not need to use welding, but can minimize the amount of welding and improve the quality. (See Fig. 2-8)

Fig. 2-8: Quick bending, the inner surface of wall of pipebent is very smooth (4"_40s & 2"_80s CS PIPE), no weld

(9) Pre-fabrication of quick-bending, better quality, less inspection and less cost:
Prefabrication of traditional industrial piping, using a large number of welding, the finished product is still in need of inspection to ensure quality standards.
Quick-bending has not any welding at the joints of bent and straight pipe (the welds of this interface of pipe/elbow is the weekest points in pipeline), and no welding inspection is necessary. Although the quick-bending is mechanized production, there are still few bad product that caused due to improper operation, such as wrinkling. Most of the inspections can be checked by visual inspection and touch. This advantage also affects the inspection of future site installations, as the number of welds in the quick-bending pipe is less and the amount of site installation inspection is less.

(10) Quick-bend prefabrication, the joints installed on the site can be arranged in the straight pipe section, and the bent joint is staggered:
The construction of traditional industrial piping will generally place the welds at the "straight pipe-elbow" joints to reduce the amount of ring-welds. This ring-weld is actually the weakest interface point in the pipeline. (Refer to Fig. 1-4)
Quick-bending processing, directly making the straight pipe into a curved pipe or a continuous curved pipe. Since the original straight pipe has a certain length, there will be remaining straight pipe sections after bending, which can be utilized as much as possible to avoid material waste. Secondly, the joint welding of the "straight pipe-straight pipe" is always easier than the "straight pipe-elbow" joint, and the quality is better. But this advantage must be complemented by improvements in the design/manufacturing drawings to truly achieve economic benefits. (See Fig. 2-9)

Fig. 2-9: Quick-bending pipe is processed according to the ISO drawing (integral molding)

(11) Quick-bending, better fluid flow at the pipebent:
    Conventional piping has ring-welds at "straight pipe-elbow" joints, and these ring-welds are often the biggest barrier to flow in the pipeline.
    Quick-bending processing, there is no ring-welding at joint of straight pipe & bends, and the inner wall of the pipe in the pipebent is very smooth and has no weld bead, which will hinder the flow obstruction in the pipebent. It helps the owner's factory to produce process efficiency.

    Secondly, the quick-bending, the maintenance and repair at the pipebent is low:
    Conventional piping will have ring-welding at the joint of "straight pipe-elbow", and these ring-welding is often the point where the owner's factory is most prone to rust, cracks, and operational safety accidents in the future operation. (Refer to Fig. 1-4)
    Quick-bending, there is no ring-welding at pipebents, it is not easy to have rust and cracks, which can reduce the incidence of operation safety accidents and reduce the loss of personnel/property/stopping of the owner's factory. Will also reduce the annual repair expenses. (See Fig. 2-10)

Fig. 2-10: There is no ring-welding process between straight pipe & bends (1.25"_160s_CS PIPE)

(12) Quick-bending, under the digital control, the same size and specifications can be used for a large number of high-precision product copying:
The traditional piping must be welded one by one by hand, which is time-consuming and labor-intensive and has poor precision.
With large machine and digital control, the quick-bending can copied in a large amount under the same specifications, which is fast and accurate. (See Fig. 2-11)

Fig. 2-11: Quick bending, which can be copied quickly, in large quantities, with high precision

2.3 Disadvantages of quick-bending technology

Having said the advantages of so many quick-bending techniques, it cannot be avoided, there are still some disadvantages. In fact, these are industrial inputs, they are not shortcomings, but they will become working capital in the future.

(1) Quick-bending must cost the purchase of precision processing machines:
If a worker wants to do something good, he must first sharpen his tools. Without high-tech /precision machining machines, quick-bending technology cannot be implemented. The price of these precision processing machines is not low, and it must be invested huge amounts of money in advance. (See Fig. 3-1)

(2) Quick-bending operators must be trained by professional operators of processing machines:
Initially, the basic operational capability was established by professional training of processing machine manufacturers. Secondly, the operator's experience and accuracy are honed through the actual operation in the factory. It cannot be rumored that this is a necessary cost of consumption. But thanks to high technology, we have been able to save a lot of training time and costs for oper.ators.
In addition to the quality of the finished product, the well-trained operators can also reduce the ratio of defective products. After all, the precision machine is also required to operate. (See Fig. 2-12)

Fig. 2-12: Good pipebent (left), bad products/wall wrinkles (right)

(3) The consumables of the quick-bending machine are quite expensive:
The large-scale machine used in the quick-bending of the pipe for heavy industrial pipelines, because of the large power, the loss of the parts. These consumables are not expensive. (See Fig. 2-13)

Fig. 2-13: Quick bending machine fixture consumables

(4) Quick-bendings must establish unique technology KNOW-HOW:
In the fiercely changing modern industry competition, organic stations and personnel can not survive only by relying on the manufacturer's machine manual. The unique technology KNOW-HOW is the keypoint of sustainable operation. In addition to the introduction of machine tools and personnel, there is also a need for deep technology to raise the competitive threshold. This paragraph is deeper and will be discussed later.

(5) Some special pipes are still required to be supplied by the owner or the main contractor:
Since the quick-bending is a part of processing, the financial resources are limited, and the procurement line is also limited. Therefore, some special straight pipe materials (materials or pipe diameters) are still required to be supplied by the owner or the main contractor to be bent. Some materials of special pipelines have long delevery times, or must be purchased from abroad, and are not suitable.

(6) Some special pipes can not be processed by quick-bending:
The quick-bending is processed by a large machine, but the machine energy and the matching mold have limitations, and cannot provide comprehensive bending processing. E.g:
(A) At present, the maximum processing pipeline size is 5”~6” diameter. If it exceeds, it can only be used in traditional elbow ring welding. We are heading towards the development of the 10"~12" diamenter processing machine, which will be gradually overcome in the future; however, it will obviously not provide all the pipe diameter processing. After all, the market will speak.
(B) Some of the extra-thick pipes cannot be bent.
(C) Some special materials of pipes cannot be bent.

(7) Quick-bending is also limited to the length of pipe:
Straight pipe generally has its length limit (for example: 6 meters), which means that after the pipe bending process, the total length of the “straight pipe + bent” is not infinitely extendable, and the necessity of ring-welding must still be necessary. The excellent manufacturing design is to fully utilize the length of the pipe and try not to waste it. (See Fig. 2-14)

Fig. 2-14: Used in LPG system, 4”_40S_CS PIPE quick-bending piping
(above: the exist. pipe of the pipeline Tie-in. below: the modification of the underground pipe to the above ground pipe)

3. The conclusion

In fact, the general type of quick-bending technology has existed for many years, and is generally a small-sized pipe diameter and thin wall cold-worked bent, which is widely used in various industries. For example: handrailing pipe in the civil construction (commonly stainless steel pipes, 1.25" to 3" Φ mostly), electric heat exhaust pipe/tubes (such as electronic parts exhaust heat copper pipes, about 1/16", 1/8" diameter, etc.), the exhaust pipe of the steam locomotive, etc., it can be seen that cold bending is a reliable technology.
Thanks to the advancement of digital technology and the help of advanced high-precision processing machines, the quick-bending technology developed by Dehan has further improved the above technology to a larger diameter (currently 5” to 6 "Φ machine, 10"/12" Φ diameter machine has been developed), the application surface is mainly industrial pipe with large internal pressure, especially the petrochemical pipeline. (See Fig. 3-1)
The petrochemical industry is a technology-intensive, capital-intensive industrial construction with certain risks, and its products are widely used in various related industries. Nowadays, the newly developed quick-bending technology can reduce costs, shorten the construction period, improve the quality, reduce the inspection, and even reduce the maintenance frequency and cost after operation and the repair cost.

The times are constantly moving forward and the environment is constantly changing. The demand of the owners is constantly improving, the prices are continuously reduced, the construction period is continuously compressed, and the work safety is continuously required to be improved. Traditional piping engineering has to use a lot of labor, a large number of parts, and a lot of time to complete, and it is gradually unable to catch up with the era. In recent years, the labor laws of Taiwan society have also been changed a lot and is transformed into another more serious situation in the future. The industry should recognize the challenges of the future. The rapid development of science and technology has brought digitalization and precision. Mechanized production methods and new business models.

The "quick-bending" technology is sufficient to meet the needs of the current era and future.

Fig. 3-1: Cold-working CNC processing machine (front and rear sides)

We provide service:

[Professional Technical Service]: scope of quick-bending processing

1. Contract construction of the construction of piping project.
2. The manufacturing of 3-D drawing specifies the bending pipe.
3. Provide non-welded pipebent/elbow fittings.
4. Other added value.

[Quick-bending Technology Advantage]: Cost reduction of the owner and improvement of pipeline quality

1. There is no need to spend the direct cost of purchasing to elbows. ...(cost down)
2. Save on non-destructive testing (NDT) and construction costs for elbow welds. ...(cost down)
3. Reduce the overall cost of the people involved in the on-site fire procedure. ...(cost down)
4. Reduce the risk of misuse of pipeline and elbow materials. ...(material quality control)
5. Omit the influence of thermal stress on the elbow weld. ...(reducing the amount of welding thermal stress)
6. Reduce the total penetration of the weld at the elbow to block the fluid disturbance! ...(no tube weld resistance)
7. Good in high speed fluid/low resistance fluid materials. ...(transportation is smoother)

We adhere to the "professional technology, service-oriented, quality-oriented" approach to the concept of sustainable management.
Talent and experience are the pillars of the project. We have accumulated more than 40 years of rich piping experience and engineering performance, and all personnel are professionally trained. Through continuous learning and accumulation of experience, we will provide you with the most professional, most complete and most efficient service quality, and hope for the support and advice of friends from all walks of life.

Technical inquiry:

email: service@dehantech.com

Manufactory:

Company: Ying Zhang Industry Co., Ltd. (Business ID: 8930 2767)
Address: No. 3-1, Lane 226, Wenxian South Road, Linyuan Dist., Kaohsiung City, TAIWAN
Tel: (+886) 07 - 642 2576 / (+886) 0932-792-307 Mr. Yu Weiqing/General Manager
Fax: (+886) 07 - 643 6184
E-mail: a89302767y@gmail.com

also see: website, Facebook

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　Brief Introduction to DH Quick-bending technology
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P1: The development of DH quick piles and the application of rapid construction in the industrial sector

Fri, 25 Jun 2021 21:51:12 +0800

The development history of DH quick piles and the application of rapid construction in the industrial sector
Li Shengnan / Deputy General Manager of Dehan Wisdom Technology Co., Ltd.
date: 2016-12-19

Note: The readers shall know that most content of this paper is translated from original traditional chinese version by software.

Foreword

DH advanced quick prestressed piles (hereinafter referred to as DH quick piles) are the pre-stressed piles developed by Dehan Company, which have improved the lack of traditional PC/PHC piles for decades and have more advantages. Most of the ideas in this article are actually described in our reference standard chart (please download from the download area of the official website http://www.dehantech.com), but the engineering drawings are often deep and difficult for the general public to understand. Therefore, the text and length of the vernacular are further explained here.

Dehan has a lot of exclusive technologies in pre-stressed piles. The DH quick piles mentioned in this article are limited to the first-order piles of Dehan Company (internal product No.: DH PLV1 type); other types of piles The technical content will be introduced later.

▲Figure 0-1: DH quick pile of 1st generation (2012), vent hole on the side wall (left)

Figure 0-2: DH quick pile of 3rd generation (2016) , with venting holes above (left)

1. The advantages and development of DH quick pile

DH quick pile (first generation) is a new generation of pre-stressed piles developed by Dehan in 2012 (Fig. 0-1). In 2015, it has developed into the 3rd generation (Fig. 0-2), which is more than traditional PC/PHC piles have engineering advantages such as short construction period, high safety, low integration cost and easy inspection.

The following will introduce the corresponding developments of DH quick piles by introducing several advantages of DH quick piles:

1.1 High security:

In fact, this is the original improvement motivation of the DH quick pile.

When we saw that the traditional PC/PHC pile was used in the "pile head treatment" after the construction of the site, the "secondary core clearing" process was used, and a large machine was used to directly drill a hole of about 2m depth on the pile head. (Fig. 1-1), the cement slurry in the inner hole is mixed with dry sand but not properly removed (it is also difficult to completely remove it) (Fig. 1-2), and then placed in the anchor cage anchored by the pile head. , refilling "expansive concrete" into pile-filled concrete.

Figure 1-: 1 traditional planting pile: secondary core processing and machine tools

Figure 1-2: Traditional planting pile: the inner wall of the pile after the core cleaned (right)

Figure 1-3: Traditional planting piles: pile heads placed in steel cages and filled core concrete

The expanded concrete used as the core of the pile head is used to make the cored concrete in the inner hole of the pile head expand slightly after drying and hard to "support" the PC/PHC pile wall concrete, and generate friction to resist the upper structure. The upward pull that is transmitted. However, the construction of piles in Taiwan's construction sites has been subdivided into sub-contracts. The small subcontractors of these "secondary core clearing" processes have low profit margins, and it is impossible to clean the internal holes of the pile heads again with industrial-grade high-pressure water jets. It is also difficult to ensure the durability of the inner hole friction. When required, it is generally only used with higher pressure water (non-water knife is very similar to car wash high pressure water). It is slightly flushed (some even high pressure water wash is not applied), this It is only possible to clarify the attached mud slightly. When the work is completed after the completion of the drilling (Fig. 1-2), which may cause the tensile force of the pile-filled concrete section to be degraded or invalid, which seriously deviates from the design. The ideal assumption of the engineer.

Therefore, the DH quick pile is designed with a "hollow pile head" and a "multi-layer pre-embedded horizontal reinforcement" in the pile head as a joint interface with the upper structure (Fig. 1-4). This design improves the frictional form of the bore of the pile in the traditional pile (which may only withstand about 20 tons), and can withstand a stable tensile load of more than 175 tons (Figure 1-5) [1] (Note: The tensile force of the pile-core filling section is not the pile pulling force capacity. So don't misunderstand it).

Figure 1-4: Hollow pile head and horizontal reinforcement of DH quick pile

Figure 1-5: DH quick pile pull test [1]

Of course, the practical use of the piles in engineering is still the main function of vertical loading. The design of the tension load is not the keypoint. In practice, there is no need to design excessive tension capacity. However, the tensile load of 100~300 tons of DH quick pile inner core filling section has also met the requirements of design engineers. In the example, in the collapse of the building in China in 2009 (Figure 1-6), we can also see some cases where the PC/PHC pile is damaged due to the tension [2].

Figure 1-6: PC/PHC piles damaged by tension during building collapse [2]

The new design of this DH quick pile head also gave us a lot of sense of accomplishment, because we completely changed and broke through the important blind spots of the pile-pushing technology introduced from Japan in the past 30 years.

[Increase the anti-microseismic capability of PC/PHC pile heads]:

    In addition to the increase and stability of the load force in the bore of the pile head, there is another advantage mentioned: increasing the resistance to micro-shock of the PC/PHC pile head. This is because the DH quick pile changes the way the pile head is combined, so that the traditional combination of the friction between the concrete and the pile wall is changed to the shear anchoring combination method depending on the preset horizontal reinforcement of the pile head, which makes the DH quick pile head. The combination of the types jumped to the mechanically coupled structural joint type.

    DH quick piles is better than traditional PC/PHC when the structure above the DH quick pile must withstand high frequency vibrations (for example, mechanical equipment with high precision requirements) or must resist micro vibrations (such as high-tech factories). Anti-vibration ability, This is in addition to the increase in tensile strength and shear resistance of the DH quick pile head, because the core-filled concrete of the traditional PC/PHC pile head will be loosened due to the long time of use, but the DH quick pile will not loosen. It is the exclusive technology of DH quick pile "the pile head never released" [3].

    If the pipe pile is designed to support highly vibrating machinery (such as heavy-duty air compressors, etc.), the vibration load of the equipment is transferred to the concrete base by the foundation bolts and then to the lower pile support. These repeated vibration loads will cause additional dynamic load on the pile-filled concrete, and the repeated interface friction will reduce or reduce the frictional strength between the core-filled concrete and the pile wall. In contrast, it will bring additional foundation. Vibration, degrading mechanical life. Buildings that accept repeated wind loads will also have similar effects on the pile foundation (Figure 1-7) [4].

Figure 1-7: Pile foundation with reciprocating load, the pile joint is also subjected to reciprocating load [4]

The new pile head design of the DH quick pile can make the precision machinery last longer, reduce maintenance and increase the home rate, or ensure its precision and increase the yield of the product in mechanical use. For some industrial mechanical operations, Or even precision industrial grade machine operation is very helpful. These industries are commonly found in Taiwan's petrochemical and electronics industries.

Since the DH quick pile does not change the shape of the pile, in the case of the outer diameter and the same pile length, the compressive bearing capacity of the pile is not increased or decreased, which must be understood by the reader. (Note: This point may be changed in other pile technology of the DH company)

1.2 Low integration costs:

Basically, the concept of PC/PHC pile cost is:

total cost
= factory fabricating cost
+ site construction cost
+ site pile head treatment cost
+ other added costs (such as manpower)
+ negative costs (such as duration)

    Due to the introduction of new technology, the DH quick pile will increase the cost of prefabrication in the factory, which will cause the outside world to have higher unit price doubts. In fact, everyone who works in engineering knows that the completion of a project is often done by a number of different types of work. The job interface is numerous (and waiting to be delayed), and many overlapping resources are wasted.

    DH quick piles have moved many of the workloads in the work of planting piles to the prefabrication stage of the factory, which is equivalent to trying to "factory" the civil work. In the production of DH quick pile heads, we must also add the main parts such as the lower dam and the horizontal ribs, which will cause some delays in the production process of the pile factory, and the cost increase is inevitable. In addition to the completion of the PC/PHC pile steaming, it is necessary to install the snorkel and the upper cover of the pile head to form our "hollow pile head". Although there are not many materials, the labor of assembling these labors is cost. These are all the costs of making DH quick piles.

    However, when the DH quick pile construction (site) are completed, the work of clearing the core of the secondary core can be omitted; at the same time, other work types can be immediately added to the work sequence, and the cost of the overall integration is not high. When the civil work is carried out on the construction site, the most cost-saving, but few people will count the cost of the process interface, it is a pity. The development of the DH quick pile is to take into account the cost integration of this part, which is to integrate the "time cost" in addition to the traditional cost of calculating only man-machines. (Note: Civil engineering work is very time-consuming but the pile work is the most time-consuming work in civil engineering)

    The "profit" based on the contractor is closely related to the "cost". Of course, it is also related to our technical interests. Let us skip the in-depth description of this part. (Note: I don’t talk about money in this article. Interested friends can talk directly.)

1.3 Short construction period:

    The DH quick pile moves many of the workloads in the work of planting piles to the prefabrication stage of the factory, so it can save a lot of construction period and labor during the construction phase. Planting piles at the construction site is a rather time-consuming task, and in the implementation of the piles, almost all the work in the construction site cannot be carried out, and all the man-made materials are "waiting". Except for the construction period of the pile-pile construction (about 15 piles per day), even if the pile is completed, the construction site still has to wait for a period of time (about 14 to 28 days) to give the pile-hole cement slurry a certain strength; The core clearing hole also requires process waiting (about 30 piles/day), and the waiting time between the work items is more time-consuming. These messy work items are all time-consuming.

    In the development of DH quick piles, "a large amount of savings during the construction period" is the mainly advantage that was once again discovered in the later stage, which is the biggest weapon of the DH pile. This period makes DH quick piles out of the stage of "sale pile products", and further merges "sale time" to customers; of course, the aforementioned high quality is also included, which is not possible with traditional PC/PHC piles.

    The engineering people know that "as long as the civil engineering work can be rushed up, other work can be rushed up." This definitely means "schedule." In civil engineering, "underground work" is the most time-consuming. If it is based on PC/PHC piles, it is the most time-consuming process of planting piles.

Due to the design of the DH quick pile hollow pile head, there is a difference in the pile construction of the DH quick pile and the conventional pile pile during the pile construction (Fig. 1-8). The hollow pile head allows the DH quick pile to be opened at the time after the soil layer is implanted, and the subsequent civil engineering process is connected. In Figure 1-3, we can clearly see that the main difference between the two is in the “process after the foundation pile is established”. The upper cover of the hollow pile head is designed to be easily opened with a manual or power tool (Figure 1-9). When the upper lid is opened, the unique design of the DH hollow pile head (Fig. 1-10) is revealed, and the preset horizontal ribs are lightly visible (Fig. 1-11). The pile heads of the subsequent civil work are anchored to the steel cage (vertical reinforcement) and can be inserted (Fig. 0-2). After filling the cored concrete, the pile work is completed (Figure 1-12).

Figure 1-8: Comparison of DH quick pile and traditional pile pile construction

Figure 1-9: Opening of the DH quick pile (manual example, simple opening)

Figure 1-10: The hollow pile head exposed after the opening of the DH fast pile
Figure 1-11: Preset horizontal ribs of the DH fast pile

Figure 1-12: DH quick pile filling core concrete (schematic)

Because the DH quick pile can make the cement slurry in the pile hole not enter the hollow pile head part of the pile top during the construction of the pile, after opening the upper cover, the preset horizontal rib and the clean hollow pile head are exposed, and the core is provided. Required for concrete infusion. The tensile design of the pile core filling section of the DH quick pile is directly embedded in the concrete of the pile wall by the preset horizontal ribs, and combined with the core-filling concrete, because the friction between the core-filled concrete and the pile-wall concrete is not required, It can be used with ordinary concrete without using expanded concrete.

Figure 1-13: Comparison of construction period of DH quick pile and traditional pile (single process)

Figure 1-14: Comparison of construction period of DH quick piles and traditional piles (process integration)

Compared with traditional piles, DH quick piles can be completed with less time (Figure 1-13) because it saves a lot of processes, which highlights the advantages of DH quick piles. Further work-process integration will have a better time advantage (Figure 1-14), which will be described later (suitable for larger and larger-area construction cases).

In the construction of the DH quick pile, we used the pre-fabrication procedure of the pile factory to add the presets of "hollow pile head" and "shoring head horizontal rib". When the construction site is constructed, the pile hole cement slurry can pass smoothly without filling up. The inner hole of the pile head. After the pile is completed (after 24 to 48 HR), the upper cover of the DH quick pile can be opened, and the pile head processing construction process of the cored reinforced concrete can be quickly carried out. This is a major feature of the DH quick pile, which can make the piled pile and the basic civil work work in a coherent manner, and there is no time to delay (of course, it does not need to be so urgent when it is officially constructed). The industry is highly efficient, and the investment recovery time is as short as possible. It is conceivable that the compression of the DH quick pile is urgent for many industrial owners.

The above is our company's "DH quick piling method" (Figure 1-8). Dehan also further developed the "DH super-quick piling method" and "DH ultra-quick piling method" for shorter construction period. Due to space/time limitations, we will have the opportunity to introduce it later.

1.4 Easy to inspection:

The completion of the foundation pile project mainly includes three: (1) factory prefabrication of the pile (including transportation), (2) construction of the pile, and (3) pile head treatment of the pile. Normally, everyone's work on piles is concentrated in the first two items, while the last integrated work is neglected, often classified as a scope of civil sub-contractor, rather than scope of piling sub-contractor. The construction period of traditional pile construction has been for a long time, and the piling sub-contractor is often reluctant to go back and deal with it, which may result in the lack of work connection.

Factory prefabrication of foundation piles: In fact, DH quick piles have not changed a lot of traditional PC/PHC piles. The factory inspection method is still based on CNS 2602 standard, plus direct supervision of production and factory inspection.
Piling construction: DH quick piles are almost the same as traditional piling methods in construction of piles at construction sites.
Pile head treatment of piles: The main difference will be between the secondary core clearing (traditional pile) and the top cover (DH pile). When the traditional pile-growing method is used to clear the core, the cleaning degree of the inner hole will be greatly caused by factors such as the case (pile diameter and inner hole depth), the seriousness of the construction work, and whether there is high-pressure water flushing. The difference (Figure 1-2) often makes it difficult for supervisors (or owners) to judge whether they are qualified or not.

　　The design of the hollow pile head has been created at the time of factory pile production. The hollow pile head is formed by the preset lower dam, the PVC vent pipe and the upper cover, so that the pile hole cement slurry does not flow. After the cover is opened, the "clean hollow pile head" is exposed, which is easy for the supervisor to visually inspect and the quality control is quite easy to implement.

　　Contracting the construction company (or small to the sub-contractor/workor class level) to seek quicker and cheaper is the convenience and profit, but also the unwritten routine in the current engineering market, the supervisors can not be so sloppy. Engineering often requires consistency of materials and construction quality, minimize differences, to facilitate the implementation of quality control, to ensure the quality of finished products after construction; when the materials are equivalent, the construction method is the source of the difference. In the traditional pile-pile construction, the secondary core drilling process often causes excessive differences and should be eliminated or phased out. This is the reason why we develop the DH pile-pile method, and it is also the advantage of the DH pile-pile method, so that the piles at the completion time The quality of the pile head can maintain considerable consistency and is far superior to the traditional pile-grilling method. (Note: Dehan also extended this significant advantage to the later application of DH 6th-level piles)

1.5 Reduce risk:

　　This is related to Dehan's DH 5th and 6th-level piles. Let me talk about it later.

2. The new concept introduced by DH quick pile in engineering

　　The advantages of DH quick piles and the differences from conventional PC/PHC piles are described above. In the process of our research and development, it is also applicable to introduce some new ideas in engineering:

2.1 Increasing the proportion of assembled work: reducing work on the site, increasing factory work, and introducing manufacturing concepts into the engineering industry

Due to the large difference in the environment of the construction site, the terrain/weather/wind are easy to be affected; and the workers are also susceptible to the corresponding impact; the workers are mostly temporarily grouped, the stability is poor, and the skill training varies greatly. All of these will affect the quality of the finished product. DH quick piles are required for the various processes in the traditional planting work, and are moved from the construction site to the factory in advance, through the equipment in the factory (such as movable cranes, automatic netting machines, etc.), production lines, and more trained workers. Class personnel, and even quality control inspection operations, can improve the quality and increase the stability of the finished product. It can also shorten the time (such as high-temperature steaming to accelerate dry and hard), and good operation can even reduce the overall cost.

The current project also pays attention to increasing the proportion of assembly work, which is used to make the quality better and the construction period shorter.

Most of the assembly work in the project is in the superstructure, such as beam/column/slab/wall, or even the bridge column in the bridge project; but it has not been seen in the foundation pile, except for the tradition. Beside the prefabricated PC/PHC pile, the DH quick pile further combines the PC/PHC pile with the upper base structure and performs a quick combination of similar assembly methods.

[Introducing manufacturing concepts into the engineering industry]:

After a century of evolution, many of the manufacturing concepts of manufacturing are commendable, especially from the factory-manufactured manufacturing of Henry Ford's automotive production line processes; and, like the "JIT System" (Just In Time) at the end of the 20th century The concept of "product just in time" and "zero inventory" has also helped the rise of large factories such as Toyota, and greatly improved the management technology of various supply parts of the production line.

On the other hand, in the construction industry, especially in the construction industry where construction is carried out on the construction site, many concepts still remain in the production methods of the last century, relying heavily on labor, measuring stakeouts, formwork, steel, concrete, etc. Need to be "manual", except for some mechanized construction tools. Of course, this is also related to the characteristics of the construction industry, that is, the method is so "technical."

In the technical improvement of DH quick piles, we focus on the interface between pile and foundation. The former is generally classified into the geo-field, while the latter is the structure field, and the interface between these two is somewhat blurred. Taking the PC/PHC pile as an example, this interface is in the "piling". Implanted piles were sourced from Japan until the 1960s. The earliest application example in Taiwan was in 1988 [5]. In the past 30 years, Japan and Taiwan have not had a better way to solve the details of PC/PHC pile head treatment, and can only be used to solve both the "expanded concrete" and the "secondary core bore depth". However, both of them are only inaccurate methods, and it is very easy to have a large number of variations with the quality of the construction workers and the professional/cautiousness of the supervisors (Figure 1-1, Figure 1-2). The degree of mechanical removal of the inner hole during the secondary core drilling, the degree of manual removal, the degree of high-pressure water cleaning of the inner hole wall [6], and the removal of residual water are all pre-processes that greatly affect the processing power of the pile head, especially It is a high-pressure water cleaning process (about NT$200-300/hole) deep in the inner hole wall. It is said that it can only be cleaned to a depth of about 1 meter. For deeper cleaning, it is almost impossible for the construction site to reach, unless it is impossible. It is the use of "industrial waterjet treatment", which is more related to the processing cost (about NT$3,000 to 5,000/hole). This cost is not borne by small subcontractors, and it is almost impossible to conduct inspections.

The DH quick pile was made. We have moved most of the processes in the pile head treatment to the "more reliable factory". After the piles are planted on the construction site, the inner holes of the clean pile heads are specifically presented as eye-catching. Even in Japan, this technology is not provided. The materials (or parts) of PC/PHC piles, core-filled concrete, civil foundations, and other parts can be concentrated in the construction site in the shortest time, or the time of stay can be minimized, similar to the production line. The concept that all parts can arrive in time. This has completely different progress from the traditional work thinking in the land management, employment management and sub-contractor management of the construction site.

2.2 Easy-opening type of pile head treatment processing

    Due to the large changes in the environment of the construction site, the terrain/weather/wind and rain are easily affected. To meet the requirements of Section 2.1 of this paper, a “clean hollow pile head” must be used to support the subsequent processes. Traditionally, the appearance of the bore in the pile head has to rely on the secondary core process (Fig. 1-1); the DH quick pile creates the "easy-opening pile head treatment process" to make it easy to practice.

    The DH quick pile cover can be easily opened (Figure 1-9). The large opening of the construction site uses a quick opening of the pneumatic/electric wrench (this is related to the number of covers and the degree of concentration. If a small amount of cover is used, the manual method is adopted). Once the top cover of the pile top is opened, the hollow pile head is exposed (Fig. 1-10). After the preset PVC vent pipe is taken out (Fig. 1-11), the preset horizontal ribs in the hollow pile head are immediately presented. This hollow pile head is used to infuse core-filled concrete (including steel cages) and is used to undertake subsequent civil foundation processes; of course, the two can also be combined.

    This is DH's original "easy-opening pile head treatment process", so that the pile-pile process can be quickly connected with the civil engineering process. Of course, the mechanical bonding force is absolutely better. (Details will be introduced later)

2.3 Creation of hollow pile heads

    To meet the requirements of Section 2.2, the hollow pile heads must be pre-assembled in the factory (Figure 2-1) before they sent to the construction site. The hollow pile head of the DH quick pile has three main parts: the lower dam, the vent pipe, and the upper cover (Fig. 2-1) (Note: The preset horizontal reinforcement has another function, but it is not the requirement of the hollow pile head). These parts must be assembled before the piles are shipped from the factory, so that they can be used in the construction site to immediately cooperate with other processes.

Fig. 2-1: Composition of DH quick pile hollow pile head
Fig. 2-2: DH quick pile hollow pile head exposed after opening

Before the fabricating of PC/PHC piles, the assembly of steel bars and spiral ribs (commonly known as netting) has already been the work of automated electric welding. Before the concrete is fed, the lower dam of the hollow pile head part must first be fixed at the design position. After the concrete is fed, the pile mold is rolled and centrifugally formed, and after the high temperature steaming, the PVC snorkel assembly and the upper cover are assembled. Thus, the DH hollow pile head is formed.

2.4 Switching to the wall of the pile to replace the tension of the pile core

The design of the pile head preset horizontal reinforcement is the most original source of creation for the DH quick pile. We have seen the combination of the "unreliable" pile heads produced in the traditional pile-grilling method, and the horizontal reinforcement have been pre-buried into the pile-wall concrete before the piles are delivered in the preset way. The shape of these horizontal ribs is also different. From the 1st generation (2011) , the "U" shaped bar (the best in strength), the 2nd generation (2013) of the "double L" shaped steel bar (the second best in strength), the 3rd generation (2015) of "straight" shaped steel bars (the worst in strength), the current horizontal reinforcement design is 6 layers, each layer of 2 steel bars intersect, with 24 concrete joints, both simplified and sufficient (Figure 2-3, Figure 2-1, 2-2).

Fig. 2-3: Horizontal ribs of DH quick pile hollow pile head

In addition to the reduction and simplification of production costs, we also consider that PC/PHC piles, which are mainly used for vertical pressure bearing, do not need to bear excessive tension, and simply extend straight into the concrete of the pile wall with straight straight steel bars. That is, it can produce a tensile strength of 100 to 300 tons. If there is a need for a higher core tensile strength, it can be easily improved by changing the number of layers of the horizontal ribs and the number of each layer. The factory is also easy to manufacture, and there is no trouble in the construction of the site.

After the pile is completed, the cover on the construction site can be opened, and the pre-assembled vertical steel cage (anchor reinforcement) can be inserted into the hollow pile head, and then the core concrete can be poured to complete the pile head treatment process. It is worth noting that in the DH quick pile, the core-filled concrete only uses ordinary concrete (210-280 kg/cm2) instead of the traditional expanded concrete.

The additional cost of the expansive concrete, whether it is added or the right amount, often depends only on the conscience of the construction contractor (or subcontractor) and the ready-mixed concrete industry, and there is no disposal in supervision and inspection. The quality of concrete placed on the ground is also poor.
After the dry concrete is dry and hard, the strength is formed and the volumetric micro-expansion effect is difficult to estimate. After many years of use (for example, 20 to 40 years), whether the expansion effect is affected by the weathering of the concrete is difficult to estimate, and these may be The loss or loss of the friction between the core-filled section and the pile wall will be difficult to prevent if there is unpredictable tension (refer to Figure 1-6).
After using the DH quick pile, the tensile strength of the pile core section has been replaced by the shear resistance of the preset horizontal rib embedded in the pile wall concrete. This force is more stable than the conventional friction. It does not detract from the need for the expansion concrete, so it is enough to use only ordinary concrete in the DH quick pile.

[Design of B-type DH quick pile]:

In order to make the DH quick piles more conservative and do not want to change the traditional pile head combination, we also designed the B type DH quick pile (PLV1B type). This type B DH quick pile retains the design of the hollow pile head, but does not design the horizontal reinforcement of the pile head, but relies on the combination of the traditional expansion of the core-filled concrete and the pile wall. Although it is not too advanced, it can be the intermediate step from the traditional pile to the DH quick pile.

    Readers who are interested in research can download our sample drawings (autocad and pdf files) from the Dehan website.

2.5 Changing the job interface problem during construction and the short-term construction period of challenging pile work

    After the DH quick pile has been mechanically innovated (see para. 2.1 to 2.3), we find that it is not easy to be favored by the owners. After scrutinizing the reasons, we found that the DH quick pile is good, but the mechanical improvement is not the focus of the owner. The consultants/engineers who undertake the design case do not like the "new things", although the DH quick pile looks It is "more solid and reliable".

    After careful analysis, it was found that "cost, construction period" is the most important concern of the owners, especially the "work period", mainly because the huge amount of investment will create financial pressure when the plant is built, and the delay in the construction period will affect the start of the factory, which will result in products. The DH quick Pile developed a "compression schedule technology" to meet the pressure and demanding owners.

    In addition to the period saving of the DH quick pile, by integrating the interface between the various types of work, including the pre-subcontractore gap (waiting for work shifts) between the types of small subcontractor (or even the work shift), entry, operation, cleaning and departure, etc., are wasting cost/period of main-contractor (also the owner's construction period). In Fig. 1-8, 1-13, and 1-14, the reader can see the details of the integration and the savings of the duration, and more importantly, the individual and overall quality is more optimized and more stable.

    The high compression of this construction period is very important for Dehan's pile technology, which allows us to further develop other technologies in the future development (for example: DH 5th-order, 6th-order, 7th-order pile technology). This is a later story, and will talk about it later.

3. The application of DH quick piles in industrial construction

    Traditional PC/PHC piles are commonly used in public/civil industrial buildings and workshops. The development and initiation of DH quick piles is also closely related to the construction of industrial buildings. This is mainly due to two aspects: safety and construction requirements (as detailed above).

3.1 Construction period: the shorter the better

    The government is the owner of public works/project. Although there are time limits(period), the legal requirements, engineering progress, and ability of contractors will often make concessions on the designation of the construction period. The most common one is the most abundant construction period. In addition to the capital investment, the industrial construction that is more biased towards the private sector still requires the output of the product (the maintenance of profit and the production line). Therefore, in the construction process, the shorter the better. Moreover, due to the environmental disputes in Taiwan and the resistance of the residents, the construction of the project is also the sooner the better. Capital investment is the pressure of capital interest, product output is profit considerations, and the rapid establishment of the factory is the event of plant construction and the ability to quickly subsidize, so as to avoid other effects. In the decision-making of construction projects, there are often requirements for shorter construction periods.

    The construction speed of DH quick piles is fast (Fig. 1-8, Fig. 1-13). If the topographical geological and structural types of the case are suitable, and the integration of the types of work, the construction speed of the DH quick pile can be made faster (Fig. 1-14).

    Use DH planting pile construction to move the site work as far as possible to the factory prefabrication (for example: hollow pile head) to shorten the construction time of the construction site, and also reduce the job interface and waiting time. This method is the best for industrial construction. the way. The use of PC/PHC piles is a common method in the industry, and DH quick piles are a further saving.

    In Figure 1-14, it is commonly seen in long-span factory buildings, which are commonly found in manufacturing plants, such as petrochemical, steel, electronics, etc., when the district is implemented (A --> B --> C --> D) (subject to availability). If the site can be excavated first, the construction period will be better. It can be connected in series for each type of work, and the construction period is shortened.

    In general construction, it is often mentioned that construction/continuous construction can be carried out immediately, but in most cases, in order to avoid unnecessary disputes or accounts, it is often waited until the previous package is completed. After completing or leaving the field, you will be allowed to pack into the work. This is the actual situation, so many construction periods can only be wasted in it; all the engineering language with continuous construction becomes a bubble.

    The technology of DH quick pile: hollow pile head, preset horizontal reinforcement, immediate opening, immediate ribbing, and immediate grouting, which has achieved better quality, construction speed, and work type integration. The ideas have become concrete practices at your fingertips. When the time pressure of building a factory is greater, or the financing pressure is high, it will show the unique superiority of DH quick pile.

3.2 Quality: The better the better
    As detailed above, we will not repeat them. The DH quick pile was made.

3.3 Inspection: the simpler the better
As detailed above, we will not repeat them. The DH quick pile was made.

3.4 Cost: The more you save the better

    Basically, DH quick piles, some parts (and labor) are added to the factory, and the cost will definitely increase. But this is only the cost of the factory, not the cost of the construction site. Considering the cost of other special processes during construction of the site, due to the special design of the DH quick pile itself (such as: reducing the secondary core/clearing process, no longer using expanded concrete, etc.), there is actually no increase.
    When considering the huge contraction period caused by the reduction of the interface time of the job, the previous cost is not so important. This is also the most important technology for DH quick piles, not the hard steel reinforcement.

4. The conclusion

    DH quick pile is the first pile technology developed by Dehan Company and has been improved to the 3rd generation. Dehan's DH quick pile is not only excellent in quality, stable, and short in construction period, it is worthy of your attention.

The article written in this article is a bit longer, stinky, messy, and boasted, and some places have been repeated (a bit of muddy water), I hope you don't mind too much.

At present, Dehan Company defines DH quick piles (1st-level piles) as "industrial grade piles", while the 6th-level piles are " Turnkey-grade piles" and the 8th-level piles are " Consortium-level piles". After that, we will make more research and development, change, and more detailed introductions of PC/PHC piles, or you can pay attention to Dehan's official website (http://www.dehantech.com) or Facebook official website. (http://www.facebook.com/dehantech/), you can also write to us to discuss mutual growth.。

References:

[1] Yantong Engineering Co., Ltd. (2014), “Dehan Intellectual Technology Company: PC Pile Head Pulling Test Report”, Table 6-2, Kaohsiung City.
[2] Lee Shengnan (2016), “Improvement of pre-stressed pile head joints – taking the collapse of the Shanghai Building as an example”, Proceedings of the 2016 Asia-Pacific Urban Construction Practice Forum (Hong Kong), Hong Kong University of Science and Technology.
[3] Zhang Jiaqi, Liu Wenzong, et al. (2013), “Application of pile head treatment technology for DH-PHC piles”, Proceedings of the 3rd China International Pile and Deep Foundation Summit, pp.197~ 206, Shanghai, China.
[4] Lee Shengnan, Zhang Jiaqi, Liu Wenzong (2014), “The latest application of DH-PHC pipe pile technology in pipe pile joints and pile head joints”, Proceedings of the 4th China International Pile and Deep Foundation Summit, pp.111 ~123, Shanghai, China.
[5] Wang Chuanqi, Xu Jianyi, Xu Mingshan (1995), “Implanted Piles and Construction Quality Management”, Journal of Geotechnical Engineering, No. 52, pp.27~36, Taiwan.
[6] Wang Yuanjing, Kitazuki Koji, and Lin Zhenping (2007), “A case study of the design of the allowable wrap stress between the PFC pile wall and the poured concrete”, Proceedings of the 12th Geotechnical Engineering Symposium, A1-14, Taiwan.

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P1: 2016-04-29 Dehan participated in the 2016 Asia Pacific Urban Construction Practice Forum (Hong Kong) and published a paper

Fri, 25 Jun 2021 21:51:12 +0800

Dehan Company participates in the 2016 Asia-Pacific City Construction Practice Forum (Hong Kong) and publishes professional papers

Note: The readers shall know that most content of this paper is translated from original traditional chinese version by software.

Dehan is proud to participate in the 2016 Asia-Pacific City Construction Practice Forum held in Hong Kong on April 4, 2016, and published a professional paper "Improvement of Head Joints of Pre-stressed Pile - Taking the Shanghai Building Collapse Case as an Example".

The "2016 Asia-Pacific City Construction Practice Forum" organized by the Alumni Association of Hong Kong University of Science and the Civil Engineering Division of Hong Kong Institution of Engineers, attended by more than 200 academics, professionals and industry representatives from mainland China, Taiwan, Macau and the local community(Hong Kong). Guests exchange of views and experiences on the three themes of sustainable development, urban/rural construction and infrastructure development.

The Dehan’s papers mainly discuss the possibility of pre-stressed piles (pre-stressed concrete foundation piles) commonly used in engineering failure in pile head construction, and possible disasters. Taking a case that has occurred in recent years as an academic research case, it is discussed with a large number of experts and scholars to seek to reduce disaster losses and casualties in future project implementation.

The direction of this paper is to study in depth from a completely different perspective, to find different engineering blind spots. Dehan company welcomes friends from the engineering community to study together.

Download:

Thesis PDF file (Traditional Chinese version - 8.7MB), (Simplified Chinese translation version - 6.7MB)

Improvement of Head Joints of Pre-stressed Pile ——Taking the Collapse of Shanghai Building as an Example

Lee Shengnan
(Taiwan) Dehan Intellectual Technology Co., Ltd. / Deputy General Manager

Summary: In the construction of Asian cities, densely populated, high-rise buildings, relatively large land demand, the use of pre-stressed piles as building foundation piles or mass rail transit(MRT) bridge foundation piles to increase the situation of basic bearing capacity is quite common. In 2009, the collapse of a new building in Shanghai, China, was based on pre-stressed piles. There were several buildings of the same type in the adjacent base. Fortunately, the building was just completed and no residents were staying. Otherwise, the disaster and the number of casualties will be an engineering tragedy. This article will explore the set joints, weaknesses and hidden dangers of the existing pile joints by means of the damaged pile foundation joints in the collapsed case of the building in the past century. Further analysis of the proposed improvement of the pile joints is expected to prevent or reduce the occurrence and damage degree of related engineering disasters in the future.

Preface

At 05:40 Beijing time on June 27, 2009, a 13-floors small high-rise building that had been basically completed but not yet delivered was built on the south side of the Jingyuan Riverside Garden, and then collapsed rapidly and the pile was broken [1 ]. This is the case of a reverse building in Shanghai. The building is based on pre-stressed piles (China called pre-stressed concrete piles, hereinafter referred to as foundation piles, piles) as the basic support structure. The purpose of this paper is to specifically discuss the structural mechanics of the pre-stressed pile failures of the foundation piles as the foundation support in this case, in order to be able to use the piles as building structures, bridge structures or other for the future engineering community. When supporting large structures, it is possible to improve and obtain a more complete and stable supporting force.

1. The collapse of the building

1.1 Historical records of the building collapse

In this case, the investigated results show that the main reason for the overturning is that the north side of the building is up to 10 meters in the short term, and the underground garage pit of 4.6 meters deep is being excavated on the south side. The pressure difference on both sides causes the horizontal displacement of the soil, which is too large. The horizontal force exceeds the anti-slide ability of the pile foundation, causing the house to fall [1]. (See Fig. 1-1, 1-2)

Fig. 1-1 shows the building collapse event [2]

In addition to the damage caused by strong earthquakes in the Japan early years, in the case of modern architecture, it is very difficult to see the damage of pre-stressed piles. This is an extremely rare case. In particular, the case where the entire core of the pre-stressed pile head is pulled out is even more rare, even in the laboratory (the experiment is generally stopped when the strain gauge reaches the displacement) . If the core-filling segment is better handled, it may be possible to make the friction of the core-filling segment more thoroughly, and it may be possible to stay longer. In this case, there is no low excavation/high filling method to support the side block, and the occurrence of the disaster should be inevitable.

In terms of structural design, the design engineer hopes that the initial damage point will occur on the "members" rather than the "joints." Therefore, in this case, the pre-stressed pile break is regular, and only “the core-filling segment is pulled out" is the biggest anomaly. Once the core-filling segment of pile head is pulled out (frictional failure), the allowable tensile force is down to zero, and the tensile force of the adjacent pre-stressed pile is greatly increased, the pre-stressed pile is gradually broken, then the building collapse is inevitable. Pre-stressed piles can increase the tensile strength of the pile by increasing the number of pre-stressed steel bars. However, the treatment of core-filling segment of the current construction method (known in Taiwan as pile head treatment, and the mainland is called pile head strengthening) is not feasible. The cement slurry in the inner hole of the pile head and the inferior concrete after the soil mixture is dry and hard are not easily removed, and the tensile strength of the core portion of the implanted pile head is worse than that of the striking pile. In the case of 30 years of implanted pile construction experiences in Taiwan, only a few tensile test reports of the core-filling segment [5][6] were used to affirm and consolidate the construction results of the pile heads, and the rest of the construction cases were mostly unknown.

After the secondary drilling of pile core and the high-pressure water clear, the interface friction of the pile core and the pile wall is conservatively taken as 0.20N/mm2 (about 2.0kg/cm2) [5], and the estimated friction of fill core of 2M depth of 600mm pile about 491 KN (about 50 tons). In order to increase the friction, only the depth of the core-filling segment is increased; but the deeper the core-filling segment is, the more difficult the cleaning of the inner hole surface is, and the rigor of the construction of the worker is more tested.

2. Improvement of the head joint of pre-stressed piles

Disasters are always sudden, abnormal, and exceed the allowable range. No one can predict the occurrence of disasters. The pre-stressed pile is an excellent building material with high cost performance (C/P value), but there are still three major defects in the upper, middle and lower parts. The pile head treatment part is the most prone to the upper end of the pre-stressed pile. In the improved DH-PHC pile construction method is to solve the problem, try to consolidate the design of the pile head joints, so that the structural components can get better performance.

Unlike Taiwan's general implanted piles (the mainland is called the buried type), the pre-stressed piles of buildings in the mainland are mostly piles of driven type (hammer type) or pressed-into type. This is similar to the construction method prevailed in Taiwan in the 1970s. Compared with the implantable method, the construction cost of the striking method is relatively lower (about 40% reduction) [4], but the pile is easily damaged due to hitting, affecting the pile durability.

In the case of this paper, we focus on the sudden damage of the pile head of pre-stressed pile. In the tensile failure of pre-stressed pile, the core-filling concrete (hereinafter referred to as the core-filling segment) of the pile head core-filling segment is pulled and pulled out of the pile. This is the most unusual case. Since the traditional core-filling segment and the pile wall are mainly transmitted by the frictional force of the interface, in addition to the material, the construction quality of the site is considerably affected, including the construction rigor of the workers/staff. When the pile head tension occurs, since the pile wall is made of concrete, and there is no proper tension connection between the pile and the upper foundation, it can only be relied on by the core-filling segment. The possibility of occurrence of tensile brittle failure increases when the tensile force of the pile exceeds the friction force of the core-filling segment of pile (including the loss or reduction of friction). In the structural design, the engineers will strive to allow the bearing capacity of the component to be greater than the external force, in order to achieve structural safety, at least to achieve the situation of early warning damage, in order to reduce casualties in the disaster.

In the treatment of core-filling segment of pre-stressed piles, there has been no better way than the design of the friction of the core-filling segments for decades. Most of the engineering designs can only use “Designed to withstand vertical pressure rather than tension” as a design criterion of foundation piles to circumvent the design of the tension. This also caused the stereotype of the pile to be pressed only without being pulled. However, the disaster does not occur as expected only in the pressure bearing. When the tensile load occurs and exceeds the designed tensile capacity, or the friction of the inner hole of the pile is lost or degraded due to the construction of the core-filling segment, the disaster will occur. It will be sudden and significant.

In research of Zhang Jiaqi (2013) [3], the tensile strength of pile head can be increased by pre-embedded the horizontal reinforcement in the pile head section when prefabricated in the pile factory (Fig. 2-1, 2-3). The combination of vertical steel bars and concrete at the construction site and the core-filling segment becomes a more reliable structural joint, and the tensile load capacity of the pile-head core-filling segment is greatly improved. Since the pile core-filling segment is completed, it is almost perpendicular to the solid concrete section (referring difference of the hollow section of pile). The anchor bars are firmly anchored into the pile wall by core-filling concrete and horizontal steel bars. With sufficient horizontal reinforcement and proper anchoring, the tensile strength of the core-filling segment can be as high as 400 tons or more. However, the pile generally is not designed as a tensile pile, and the required allowable tensile force is not high, and only the tensile capacity of the pre-pressed steel bars can be satisfied.

Fig. 2-2 shows the compacted type of the horizontal reinforcements of the DH-PHC pile head. The horizontal bars no longer use the hooks, only the straight bars, which are simplified and lower the cost. The pile core-filling segment is subjected to tensile force. When the horizontal bar has 1-2 hooks, the horizontal bar can exert the full shear capacity. The shear capacity of horizontal bars will be controlled by the compressive stress of the projected area of the horizontal bar into the pile wall concrete (diameter*penetration depth) if the horizontal bars don’t have any hook (straight type),. Although the tensile strength of the core-filling segment is slightly reduced, the tensile capacity of pre-stressed bars can still be satisfied. Of course, in the case of special needs (for example as a tensile pile design), the horizontal bars can still be set to provide greater tensile strength.

Fig. 2-1 Horizontal bars of DH-PHC pile head Fig. 2-2 Horizontal bars of compact DH-PHC pile head

Fig. 2-3 DH-PHC pile horizontal bars are assembled and embedded into the pile wall concrete

In design, the pile core-filling segment will adopt the pre-embedded horizontal bars. After combined with core-filling concrete, the horizontal bars will be embedded in the pile wall concrete, and the steel section will exert sufficient strength to bear the pressure. The bearing type transfers the tension of the core-filling segment to the pile wall. The transmission mode of its pulling force is as follows:

The pile head is subjected to tensile force --> vertical anchoring bar is pulled --> transferred by the reinforcing force of the bar to the core concrete --> transferred to the horizontal bar --> transferred to the pile wall concrete --> pulled by the high-strength pre-stressed bar in the pile wall --> transferred to the full length of pile body --> transmitted to the soil by the friction of the pile body.

In the design of the horizontal reinforcement of pile head, the depth of the horizontal bars into the pile wall and the width of the steel bars are taken as the bearing area, and the allowable bearing capacity is controlled by the number of layers, the numbers and the diameter of the horizontal bars. The size can be adjusted by the design engineer.

The bearing pressure of a single end point of a single horizontal bar can be controlled by the following two values:

Shear strength of steel bars, Fhbs1 = As1*fva*Φss ...... (1)
Pile wall concrete bearing pressure, Fhbc1 = Asc*fc' *Φcb ...... (2)
Fhbv1 = min( formula (1) , formula (2) ) ...... (3)
The total supporting force is
Fhbv = Fhbv1*Nhb ...... (4)

In the formula, As1 = single bar area (mm2). fva = allowable shear stress (N/mm2), taken as bar's yielding strength fy. Φss = steel shear reduction factor, taken as 0.75. Asc = Pile wall concrete bearing area (mm2), taken as db*Lhb, db=rebar nominal diameter (mm), Lhb=depth of horizontal bar embedded into pile wall (mm). fc' = concrete compressive strength of pile wall (N/mm2), taken as 78.5 N/mm2 (or 800 kg/cm2). Φcb = concrete bearing pressure reduction factor, taken as 0.65. Nhb=the total numbers of support points of horizontal bars, taken as (the number of horizontal bar layers * the number of steel bars per layer * 2 end points). [8]

Since the horizontal bars of the DH-PHC pile is limited by the thickness of pile wall, it will affect the protective cover thickness of the bar [7], and it is not enough to penetrate the pile wall. Therefore, the pile at the smaller outer diameter (i.e. the pile wall is thin), the shear capacity of bars will be limited by the concrete bearing pressure of pile wall. Fortunately, the concrete used in pre-cast piles is high-strength concrete (such as 78.5N/mm2), which can exert a considerable bearing pressure. The total capacity of horizontal bars is still large and stable compared with the traditional core-filling concrete friction. Moreover, the design engineer can change the total number of horizontal bars to increase the allowable tension.

Table 2-1: Tensile capacity of various pile diameter DH-PHC pile core-filling segments under the recommended horizontal bars

From Table 2-2, we can find effect is better that the horizontal bars of the core-filling segment use 2 smaller diameters (such as 2-D16mm) than the one with a larger diameter (such as 1-D19mm). This is based on the fact that the total vertical projection area of horizontal bars embedded into the pile wall is large. However, if the horizontal bars are provided with hooks, the effect is different.

2.2 Advantages of the implantable construction method using DH-PHC piles

The implanted type of construction method (buried type) has been implemented in Taiwan and Japan for more than 30 years. Although the construction cost is high, it is recognized as a method to maintain the optimum component performance of the pile. In the out-drilling implanted method, after the pile is implanted into the soil, it is necessary to do a secondary work use a large drilling machine to drill a hole in the pile head, and then cleaning the hole, so that the inner wall surface of the hole may have enough good contact surface.

Fig. 1-2 Photo of the building collapse event [2]

Fig. 1-3 Photo of the building collapse event [3]

1.2 Discussion on the failure reasons of the building supported by pre-stressed piles

According to the investigated report of the year, this case was caused by the “pressure difference” on both sides of the building due to the excavation of the underground garage (4.6M) on one side and the overfilling side (about 10M) on another side. The "pressure difference" on both sides of the building is the cause, and it has been apparent for some time. The construction of the 13-storys building is definitely more than 28 days, and the strength of the concrete members has been fully utilized. The "pressure difference" on both sides caused the horizontal shear force to be too large, and the building had an "abnormally large overturning moment", which eventually led to the failure of foundation piles as a geological improvement.

There may be three reasons for failure of the pre-stressed pile: failure of compression, failure of tension, failure of shearing. According to the scene photos published in the media in the same year (see Fig. 1-3), only the exposed parts can be seen. This part is subject to the pull side. We have no way of knowing the failure of the pre-stressed pile on the pressure side of the building (because being pressed under the building, perhaps the photo is also blind to some shooting angles)

When the pre-stressed pile fails to be pulled, the point of maximum tensile force occur at the higher portion of pile body, generally occurs near the interface of pre-stressed pile and foundation cap. There are several situations:

(1) Occurs in the pre-stressed pile and the foundation cap interface: it may be that the vertical anchoring steel bar fails to break.

(2) Occurs in the core-filling segment of the pre-stressed pile: it may be that the concrete friction of the core-filling segment fails, and the worst part is that the entire core-filling segment is “pulled out”.

(3) Occurs below the core-filling segment of the pre-stressed pile: it may be that the pre-stressed pile itself has failed to break. Generally, the pre-stressed pile body is designed to withstand the "pressure", and the allowable tensile force may be only about 1/5 to 1/10 of the allowable bearing pressure. Since the concrete material of the pile wall is not design to the tensile force, the tensile force is absorbed by the pre-stressed steel bars. The reason why most of the pre-stressed bars of piles hasn’t be seen in Fig. 1-3 is that the pre-stressed steel bars are “shrink back” into the pile walls after the break, and it don’t mean there is not steel bars.

When the "pressure difference" on both sides of building has been present, the pre-stressed pile on the tension side is subjected to "abnormal tension". The driven type of pre-stressed piles are mainly made of high-strength concrete (fc'=78.5N/mm2 or 800kg/cm2, similar to C80 specifications for hammer piles in mainland China) and high-strength steel bars (fy=1,227N/mm2 or 12,500kg/cm2) and spiral bars are combined and pre-stressed. The pile body material is quite rigid and basically has no ductility. Once the damage(tension failure) occurs, it is directly "brittle destruction". The building is mainly composed of beam-column-slab-wall members, and the overall structure has a certain degree of flexibility and elasticity, which is softer than the pre-stressed pile. If the building fails as a single pre-stressed pile in the support, the allowable tensile force of this pile is “returned to zero” and must be shared by the adjacent piles. In terms of structural design, usually the piles are not designed to "withstand the tension force", and the allowable tension force is lower, so it is prone to "chain breaking and collapse without warning". Of course, it will also fail to the "abnormal pressure" of the pre-stressed pile on the pressure side of the building; when the pile is damaged by pressure, the force will be transmitted to the soil layer, because the pile body strength is much greater than the soil. Intensity, unless the bottom of pile enters the rock (Note: the site of this case is the alluvial soil layer of the river bank), otherwise it will eventually lead to soil collapse and subsidence. However, this case has been judged to be a case of tensile damage of pre-stressed pile.

According to the photo (see Fig. 1-3, the estimated pile diameter is estimated from the proportion of the human in the photo). The pre-stressed pile diameter is about Φ600mm, the pipe wall thickness is 100mm, and the inner hole (core-filling segment) diameter is Φ400mm. There are two failures of piles on the pull side:

(1) The pre-stressed pile itself is "broken". If the exposed tubular member is, the breakpoint should be near or below the junction of the core-filling segment;
(2) The core-filling segment of the pre-stressed pile is “pulled out”. The member exposed in the upper right corner of the photograph in Fig. 1-3 is a flat, light-colored cylinder of smaller diameter;

When the pre-stressed pile is damaged by tension, it is normal for the pile body to be pulled off. But the core-filling segment is broken, which is abnormal. Especially, the whole section of the core-filling segment is pulled out, the friction did not play or fail at all on the pile internal hole interface. The construction method of pre-stressed pile is mainly driven type or pressed-into type in the mainland China. The pre-stressed pile internal hole after piling is still clean, and the interfacial friction of core-filling segment is relatively high. In Taiwan, implanted pile always used, the secondary core-drilling process is still required after complete piling. It can increase the roughness of the inner hole, but the inner hole surface of the pre-stressed pile is still inferior cement slurry, and the friction of the core-filling segment after casting concrete is relatively poor (refer to the same case of core-filling concrete) (see Fig. 1-4). [5][6]

Fig. 1-4 The situation of traditional implanted pre-stressed pile head secondary core clearing residual inferior concrete

The pre-stressed pile wall distributed with high-strength shaped steel bars. When the pile body is subjected to tensile force, although the allowable tensile strength of the pile-wall concrete is lower, the pre-stressed steel bars can still withstand the tensile force. Table 1-1 shows the pile tensile capacity of the TYPE C pre-stressed pile (been pre-stressed at 7.85 N/mm2, or about 80 kg/cm2). It can be seen that the tensile capacity of the 600 mm pre-stressed pile is 638 KN or about 65 tons. It’s abnormal if the pile body is damaged when the tensile force does not exceed this allowable value. For example, the core-filling segment of pile has been pulled out. The foundation pile is damaged by tension and is brittle failure without warning. It is extremely easy to cause chain damage. In the upper right corner of the picture in Fig. 1-3, it can be seen that the core-filling segment of pile is pulled out and is broken, but may be the piles near pressured side of building have not been damaged. Otherwise, it is presumed that the core-filling segment will be fail due to the inclination of the building, rather than being pulled out.

Table 1 -1 Tensile capacity of existing pre-stressed piles

Except the damage caused by strong earthquakes in the early earthquakes in Japan, in the case of modern architecture, it is very difficult to see the damage of pre-stressed piles. This case is an extremely rare case. In particular, the case where the entire core-filling segment of the pile head is pulled out is even more rare, even in the laboratory (the experiment is generally stopped when the strain gauge reaches the displacement) . If the core-filling segment is better handled, it may be possible to make the friction of the core-filling segment more thoroughly, and the building may be possible to stay longer. In this case, there is no low-excavation/high-filling method to support the side block, and the occurrence of the disaster should be inevitable.

In terms of structural design, the design engineer hopes that the initial damage point will occur on the "member" rather than the "joint". Therefore, in this case, the pre-stressed pile break is regular, but the "filling core-filling segment is pulled out" is the biggest anomaly. Once the core-filling segment is pulled out (frictional failure), the allowable tensile force is down to zero suddenly, and the tensile force of the adjacent piles is greatly increased. These pre-stressed pile is gradually broken, and the building damage is inevitable. Pre-stressed piles can increase the allowable tensile force of the pile body by increasing the number of pre-stressed steel bars. However, the core-filling segment of the current construction method (known in Taiwan as pile head treatment, and the mainland is called pile head strengthening) is not feasible. The cement slurry in the inner hole of head head and the inferior concrete after the soil mixture is dry and hard are not easily removed, and the tensile capacity of the core-filling segment of the implanted pile is worse than that of the driven pile. In the case of pass 30 years of implanted piling construction in Taiwan, only a few of the core-filling tensile test reports [5][6] were used to affirm and consolidate the construction results of the pile heads, and the rest of the construction cases were mostly unknown.

After the secondary drilling and high-pressure water clearing of pile head core, the friction on the interface of the core-filling segment and the pile wall is conservatively taken as 0.20N/mm2 or about 2.0kg/cm2 [5], and the estimated tension capacity of a 600mm pile with core-filling segment of 2M depth is about 491 KN or 50 tons. Increasing the depth of core-filling segment is the only way to increase the friction force. But the deeper the core-filling segment is, the more difficult the cleaning of the inner hole surface is. The rigor of the construction of the worker would have been more tested.

2. Improvement of the joint of pre-stressed piles

Disasters are generally sudden, abnormal, and exceed the allowable range. No one can predict the occurrence of disasters. Pre-stressed piles are an excellent building material with high cost performance (C/P value), but there are still three major defects in the upper, middle and lower parts. The pile head treatment part is the most prone to the upper end of the pre-stressed pile. In the improved method of DH-PHC pile is to solve the problem, try to consolidate the design of the pile head joints, so that the structural components can perform better.

Unlike Taiwan's general implanted piles (it is called the buried type in mainland China), the pre-stressed piles of the buildings in mainland china are mostly piles of driven type (or pressed-into type). This is similar to the construction method prevailed in Taiwan in the 1970s. Compared with the implanting construction method of piling, the construction cost of the driven method is relatively lower (about 40% reduction) [4]. But the pile is easily damaged due to hitting, and it would affect the durability of the pile.

In the case of this paper, we focus on the sudden damage of the pile head of pre-stressed pile. In the pre-stressed pile tensile failure, the core-filling segment of reinforced concrete is pulled and pulled out of the pile. This is the most unusual case. Since the traditional core-filling segment and the pile wall are mainly transmitted by the frictional force of the interface. Except the material, the construction quality of the site is considerably affected, including the construction rigor of the workers/staffs. When the pile head tension occurs, since the pile wall is made of concrete, and there is no proper tension connection between the pile and the upper foundation, it can only be relied on by the core-filling segment of pile. When the tensile force of the pile exceeds the friction capacity of the core-filling segment of pile (including the loss or reduction of friction), the possibility of occurrence of tensile brittle failure increases. In the structural design, the engineer will strive to allow the bearing capacity of the component to be greater than the external force, in order to achieve structural safety, at least to achieve the situation of early warning damage, in order to reduce casualties in the disaster.

In the treatment of the core-filling segment of piles, there has been no better way than the design of the friction of the core-filling segments for decades. Most of the engineering designs the foundation piles to “withstand vertical pressure rather than tension” as a design criterion to circumvent the design of the tension. This also caused the stereotype of the pile to be pressed only without being pulled. However, the disaster does not occur as expected only in the pressure bearing. When the tensile load occurs and exceeds the designed tensile capacity, or the friction of the inner hole of pile is lost or degraded due to the poor construction of the core-filling segment, the disaster will occur. It will be sudden and significant.

In research of Zhang Jiaqi (2013) [3], the tensile capacity of pile head can be pre-embedded by the horizontal reinforcement in the pile head section when pre-casted by the pile factory (Fig. 2-1, 2-3), with the combination of vertical steel bars and concrete at the construction site and the core-filling segment becomes a more reliable structural joint, and the tensile capacity of the core-filling segment is greatly improved. Since the core-filling segment of pile head is completed, it is almost perpendicular to the solid concrete section (referring to the hollow tubular section of pile). The vertical anchor bars are firmly anchored into the pile head by combination with core-filling concrete and horizontal steel bars. With sufficient horizontal bars and proper anchoring, the tensile capacity of the core-filling segment can be as high as 400 tons or more. However, the general pile is not designed as a tensile pile, and the required tensile force is not so high, and it’s enough to simply meet the tensile capacity of the pre-stressed steel bars.

Fig. 2-2 shows the compacted type of the horizontal bars of DH-PHC pile head. The horizontal bars no longer use the hook or hooks, only the straight bars, which are simplified and lower cost. The pile core-filling segment is subjected to tensile force. When the horizontal bar has a hook or hooks, the horizontal bar can exert the full shear capacity. However, when the horizontal bar does not have a hook (straight type), the shear capacity of the horizontal bar will be controlled by the compressive stress of the projected area of the horizontal bar into the concrete of the pile wall (diameter * penetration depth). Although the tensile strength of the core-filling segment is slightly reduced, the tensile capacity of the pre-stressed steel bar can still be satisfied. Of course, in the case of special needs (for example as a tensile pile design), the horizontal bars can still be set to provide greater tensile capacity.

Fig. 1-4 The situation of the traditional implanted pre-stressed pile head with secondary core clearing residual inferior concrete

(omitted below)

Interview Mr. Lee Shengnan (Dehan Co.) after the 2014 summit

Fri, 25 Jun 2021 21:51:12 +0800

Interview Mr. Lee Shengnan (Deputy General Manager,Dehan Co.) after the 2014 summit

Note: The readers shall know that most content of this paper is translated from original traditional chinese version by software.

Dehan Intellectual Technology Co., Ltd.(Taiwan) participated in the 4th China International Pile and Deep Foundation Summit (Shanghai) from March 26th to 28th, 2014. Mr. Lee Shengnan, Deputy General Manager, presented the "DH-PHC Pile" of the latest application of technology in pile joints and pile head joints was heatedly discussed by the guests.

After the publication, the guests were actively communicated with the Dehan's staff, which was much more than the general booth. Let's take a look at the charm of Dehan's technology products.

Lee Shengnan, deputy general manager, published the latest DH-PHC pile technical paper

Interview with Mr. Lee Shengnan, and ask him to talk about the characteristics of DH-PHC pile technology.

For related information, please refer to the file download area or download directly:

Interview with Desheng Company Lee Shengnan, Deputy General Manager after the 2014 Summit
(Simplified Chinese Edition) (Tradition Chinese version)
2014 4th China International Pile and Deep Foundation Summit Website: www.pilingchina.com

Mr. Lee published DH-PHC technology at the 4th China International Pile and Deep Foundation Summit

Fri, 25 Jun 2021 21:51:12 +0800

Lee Shengnan (Vice President of Desheng Co.) published the DH-PHC Technology at the 4th China International Pile and Deep Foundation Summit

Note: The readers shall know that most content of this paper is translated from original traditional chinese version by software.

Dehan Intellectual Technology Co., Ltd.(Taiwan) participated in the 4th China International Pile and Deep Foundation Summit (Shanghai,2014). Mr. Lee Shengnan, deputy general manager, presented the latest technology "DH-PHC pile technology in the latest application of pipe pile joints and pile head joints".After the press conference, the guests warmly discussed with Mr. Lee and staffs.

Lee Shengnan, deputy general manager, released the latest DH-PHC pile technology

Mr. Lee Shengnan on summit

After the publication, experts came to discuss:

For related information, please refer to the file download area or download directly:

The latest application of 2014 (Dehan) DH-PHC pile technology in pile joints and pile head joints (Simplified Chinese version)
2014 China International Pile and Deep Foundation Summit DM (Simplified Chinese version)
The 4th China International Pile and Deep Foundation Summit (2014), Website: www.pilingchina.com

Dehan is to publish “The technology of DH-PHC composited concrete pile its rapid construction method” (P series LV.5) in Shanghai 2015-4-23.

Fri, 25 Jun 2021 21:51:12 +0800

Dehan is to publish “The technology of DH-PHC composited concrete pile & its rapid construction method” (P series LV.5) in Shanghai 2015-4-23.

Following years of participation in the (2013,2014) third & fourth "China International Summit of piles and deep foundations" (Shanghai), have released the latest technology DH-PHC pile. This year, the Dehan participants released the latest global "Technology of DH-PHC composited concrete pile & its rapid construction method".

“The technology of DH-PHC composited concrete pile” introduced in civil engineering "risk management" concept, in order to reduce the "project risk, financial risk, and decision risk", the main method is "a significant reduction in costs, substantially shorten the construction period, heightly raise of quality, eliminate human negligence". Overall, due to extensive cost reduction of 25% to 50%, the DH-PHC composited pile is expected to quickly enter the practical engineering level. By then, please advanced sectors, dial driving advice.

Dehan Tech. Co. issued the newest DH-PHC technology on 2014 China International Piling and Deep Foundations Summit (Shanghai)

Fri, 25 Jun 2021 21:51:12 +0800

Dehan Tech. Co. issued the newest DH-PHC technology on 2014 China International Piling and Deep Foundations Summit (Shanghai)

Note: The readers shall know that most content of this paper is translated from original traditional chinese version by software.

At 2014-3-26, Dehan Co. join the 4^th China International Piling and Deep Foundations Summit (Shanghai), and issued the newest technology for DH-PHC pile conection.

The summary of this newest technology will be issued on this website soon.
For more information, please refer to chinese version in website.

* Improve enginneering technology is our job, improve human life is our belief.

Mr. Lee shang-nan /vice GM announced the newest technology for DH-PHC pile conection on 2014 summit.

2013-03-20 Questions of guest of summit about Dehan DH-PHC pile technology, QA(2)

Fri, 25 Jun 2021 21:51:12 +0800

Questions about the DH-PHC pile technology of Dehan Company during the 3rd China International Pile and Deep Foundation Summit (Shanghai,2013) Q&A (2)
(hammer type and press-in type pile only)

Dehan Intellectual Technology Company(Taiwan), released on: 2013-4-08

Note: The readers shall know that most content of this paper is translated from original traditional chinese version by software.

Dehan Intellectual Technology Co., Ltd.(Taiwan) participated in the 3rd China International Pile and Deep Foundation Summit (2013-3-20~22), and published the paper "DH-PHC Drilling and Implanting Pre-stressed Piles Application" and the latest engineering technology of the company "The next generation of pile standards: the pile head technology that never comes loose - the application of DH-PHC prestressed piles in hammer type and press-in type piles". The leaders and guests of the conference were warmly inquiring and asking questions about various products. Due to the limited participation time of the summit and some of the documents that we stated were not available, the guests could not clearly understand the product characteristics of the company. This special part of the guest asked questions and explained.

Note: This article describes only for implantable piles. The Q&A parts of Q3~Q7 are mostly the same as the hammered DH-PHC piles.

Q&A file download: Traditional Chinese version , simplified Chinese version.

Q1: At present, the hammer-type or press-in type PHC piles are commonly used in mainland China. Can Dehan's "DH-PHC Drilling and Implantable Pre-stressed Piles” be applicable?
Q2: Dehan's latest technology "Next generation pile standard: never-loose pile head technology - DH-PHC prestressed pile in hammering, press-in pile application", used in hammer-pile, What is the cost of the pile?
Q3: Dehan's "The next generation of pile standards: the never-loose pile head technology - DH-PHC pile", can really "never loose"?
Q4: Dehan's "The next generation of pile standards: the never-loose pile head technology - DH-PHC pile", does the horizontal shear resistance of the pile head increase?
Q5: Does Dehan's "Never-loose pile head technology - DH-PHC pile" product have more applications?
Q6: What is the purpose of the development of "Never-loose pile head technology - DH-PHC pile"?
Q7: What is the current progress of Dehan's "Next Generation pile Standard: Never-loose Pile Head Technology - DH-PHC pile" product in mainland China?

2013-03-20 Questions of guest of summit about Dehan DH-PHC pile technology, QA(1)

Fri, 25 Jun 2021 21:51:12 +0800

Questions about the DH-PHC pile technology of Dehan Company during the 3rd China International Pile and Deep Foundation Summit (Shanghai,2013) Q&A (1)
(hammer type and press-in type pile only)

(Taiwan) Dehan Intellectual Technology Company, released on: 2013-4-01

(Taiwan) Dehan Intellectual Technology Co., Ltd. participated in the 3rd China International Pile and Deep Foundation Summit (2013-3-20~22), and published the paper "DH-PHC Drilling and Implanting Pre-stressed Piles Application" and the latest engineering technology of the company "The next generation of pile standards: the pile head technology that never comes loose - the application of DH-PHC prestressed piles in hammer type and press-in type piles". The leaders and guests of the conference were warmly inquiring and asking questions about various products. Due to the limited participation time of the summit and some of the documents that we stated were not available, the guests could not clearly understand the product characteristics of the company. This special part of the guest asked questions and explained

Q&A file download: Traditional Chinese version , simplified Chinese version.

P1: 2013-3-20 Dehan participated in the 3rd China International Pile and Deep Foundation Summit

Fri, 25 Jun 2021 21:51:12 +0800

Dehan participated in the 3rd China International Pile and Deep Foundation Summit (2013, Shanghai)

Dehan Intellectual Technology Co., Ltd. (Taiwan) is honored to participate in the "3rd China International Pile and Deep Foundation Summit" held at the Galaxy Hotel in Shanghai, China from 2013-3-20 to 22. And successfully published the paper "DH-PHC Application of pile head treatment technology for implanted pre-stressed piles" and the latest engineering technology of Dehan co. "The next generation of pile standards: the pile head technology that never comes loose - DH-PHC prestressed pipe piles in hammer type and press-in type of piles."

During the meeting, the leaders of the engineering industry and the guests were enthusiastic about the engineering and technology of Dehan Company. We are deeply grateful to the company and can provide a heart for the new generation of engineering construction in mainland China. Mr. Shen Baohan, Chairman of the Beijing Construction Engineering Research Institute of the Summit, has several times to show that the new technology presentations brought by Dehan Company have brought another vitality to the industry! In particular, it reveals the long-term instability and uncertainty in the joint between the prestressed pipe pile and the upper foundation, providing a permanent solution! Geotechnical engineering experts and scholars, advanced and international, are warmly coming to the booth of the company to discuss and communicate. The company's pile head treatment technology can indeed improve the defects and defects in the traditional process method, so that the pipe pile foundation can be safer. More stable, more intensive, and there will be no hidden dangers in construction quality!

Thanks to Professor Shen Baohan for his assistance and support, we also promised Professor Shen that if time and technical time permits, Dehan will publish one or two more powerful new PHC pipe pile technology next year. The upcoming 2014 Summit will introduce you to the updated engineering technology of Dehan Company.

Due to the limited time of this summit, we have not been able to fully explain the improvement and application of DH-PHC pile head technology for all the advanced predecessors in the engineering industry. You are welcome to visit our website for lastest information. You are also welcome to email us and discuss with us.

(This paper was published by Prof. Zhang Jiaqi)

Application of DH-PHC head treatment technology of piles:

Paper , PPT (Simplified Chinese version),
Paper , PPT (Translated Chinese version)

The next generation of pipe pile standards,
Never loosen pile head technology LV1,
oversized pile head technology LV5 (Simplified Chinese)

2013 The 3rd China International Pile and Deep Foundation Summit Website: www.pilingchina.com