Analytical Testing of Advanced Butt Fusion Technology

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ANALYTICAL TESTING OF ADVANCED BUTT FUSION

TECHNOLOGY FOR HDPE PIPE

Steve D. Sandstrum

ISCO Industries, LLC

Dick McKinley

Fast Fusion, LLC

ABSTRACT: The market for high density polyethylene (HDPE) pipe continues to expand across avariety of end use applications. As this growth continues to accelerate, users within the

market place have become more familiar with the traditional method of joining HDPEpipe, namely butt fusion, and have become more educated in the benefits, challenges and

potential impact this joining method may have on project economics. In recent years,

however, advancements in butt fusion technology have paved the way for improved

efficiencies in the joining of HDPE pipe. This paper will focus on one of theseadvancements which has recently been introduced to the North American market and has

become known as automated mobile fusion technology. The discussion which follows

explains the technology associated with this joining technique and presents the analyticaltesting undertaken to verify the integrity of HDPE pipe joints made with this adaptation

of the butt fusion procedure. The discussion shall conclude with example comparisons of the improvements in job site efficiency achieved with this technology as compared to theconventional butt fusion joining process.

INTRODUCTION:

High density polyethylene pipe (HDPE) has long been established in the market as a

preferred material for demanding municipal and industrial piping systems. HDPE’s surgecapacity, light weight, and flexibility have made it a logical choice for direct burial or

“trenchless” placement of potable water lines and force main sewers. The chemical and

abrasion resistance of HDPE pipe combined with its overall toughness and durabilityhave also made it an ideal candidate for industrial piping systems such as mine

dewatering lines, gas and oil gathering, chemical and mineral processing, fines and

slurries lines and many more highly aggressive applications.

The butt fusion method of joining HDPE pipe and the “leak-free” joint performance

which it affords has been inherent to its overall success in the broad array of applications

for which it is utilized. Over the years, fusion joining technology and the equipment



involved has continued to evolve. This evolutionary process has held two key benefits

for the industry. First, is the continued expansion in the recognition of the long-termintegrity of the properly made butt fusion joint. The second benefit is the greater

confidence and versatility of the butt fusion system of joining afforded by advancements

in equipment technology. From the very early days of HDPE pipe’s first use in North

America, the industry has witnessed tremendous strides in equipment durability and,hence, reliability in the field. More recent advancements have been focused on fusion

mobility, process automation and computerized fusion parameter recording.

This paper will examine yet another step in the evolution of the butt fusion process for

HDPE pipe, automated mobile fusion technology, or AMFT. To facilitate this, we willbriefly re-cap the general butt fusion procedure as it has been developed to this point in

time, including advancements in automation and data recording. From this, the latest

advancement in butt fusion technology referred to as automated mobile butt fusion will

be introduced and reviewed. Industry recognized testing of butt fusions made using thistechnology will then be presented and discussed. This paper will then conclude with a

brief summary of job site benefits associated with deployment of the automated mobilefusion technology and its overall impact on job-site productivity.

TRADITIONAL BUTT FUSION:

From the early days of its use in the oil and gas fields of the United States, the technique

used to join HDPE pipe has been key to its continued growth and expansion. All along

the way from those days of “hot plate” welding to today’s self-contained and highlyautomated fusion equipment, the integrity and reliability of the butt fusion joint has paved

the way for more creative and challenging uses of HDPE pipe. Through continued

research and development, we now have butt fusion equipment that is highlysophisticated and, at the same time, extremely durable and capable of withstanding the

rigors of nearly any pipeline construction setting.

Figure 1: Early Days of HDPE Fusion Figure 2: Today’s Fusion Technology (Courtesy Phillips Driscopipe) (Courtesy McElroy Manufacturing)



Notwithstanding the technological advancements that have been realized, thefundamental butt fusion method of joining HDPE pipe has not changed significantly. As

noted within various industry publications, the butt fusion procedure is still comprised of

the following basic steps. (1),(2)

The Basic Steps of the Butt Fusion Method

1. Clamp and align the pipes to be joined.

2. Face the pipe ends to establish clean, parallel surfaces

3. Align the pipe profiles4. Melt the pipe interfaces

5. Join the two profiles together by applying the proper fusion force

6. Hold under pressure until the joint is cool

While the advancements in fusion technology over the years have been numerous, the

basic process remains largely the same as it did in the early days. Place the pipe ends tobe fusion joined in a suitably designed piece of equipment that can securely hold therespective pipes in a concentric fashion. Use a suitable device to “square” the pipe ends.

That is, to clean them up or “face” them in a consistent fashion such that the resulting

pipe faces are parallel in orientation. Once that is complete, a heat source is placedwithin the interface of the two pipe joints to achieve a uniform roll-back bead. The heat

source is then removed and the pipe faces brought together at a suitable fusion pressure

and held there until the joint is cool enough to be maneuvered out of the fusion

equipment in a safe and efficient manner.

The advancements or improvements in fusion technology have occurred principally in the

area of equipment improvements such as pipe alignment and holding capacity, pipediameter capability, mitered fitting capability, pressure control, heating and temperature

control technology, job-site durability and portability of the fusion equipment itself and,

of course, automated data recording. Clearly, each of the improvements has, in its ownway advanced the technology by which we continue to join HDPE piping systems.

However, the fundamental process by which we position and place the pipe in a fusion

machine, grip it throughout the various steps of the butt fusion method, and, subsequently

remove the completed pipe string from the fusion equipments has not changedsignificantly.

AUTOMATED MOBILE FUSION TECHNOLOGY:

Automated mobile fusion technology (AMFT) represents the latest innovation in HDPEpipe joining technology. As shown in Figure 3, AMFT may appear to be a radically new

approach to butt fusion joining technology when in reality it is based on the traditional

six step approach previously described. What is different is the overall approach to theissues associated with the handling and conveyance of the pipe, the environment in which



the fusion joint is made and the approach to cooling and holding of the freshly made

fusion joint.

Figure 3: Automated Mobile Fusion Machine on the Job Site

(Courtesy Fast Fusion)

Figure 4: Automated Mobile Fusin Machine with Stinger Deployed

(Courtesy Fast Fusion)



First and foremost, AMFT is a mobile, self-contained fusion apparatus that provides a

climate controlled environment in which to make the pipe fusion joint. The AMFTfusion vehicle is driven down the pipeline right-of-way along which the HDPE pipe has

been unloading and positioned for in-line joining. As the vehicle progresses along the

right-of-way, the leading “boom” or “stinger” picks a piece of HDPE pipe off of the

ground and the forward progression of the vehicle propels the pipe into the cab of thevehicle. As each pipe joint is fed into the cab it is loaded into an industry standard butt

fusion apparatus which has been installed in an in-line orientation with the vehicle’sdirection of travel and, hence, the pipeline right-of-way.

Figure 5: Interior of AMFT Cab Showing Fusion Configuration(Courtesy Fast Fusion)

The standard butt fusion apparatus housed in the climate controlled cab is then utilized to

make a typical butt fusion between two successive joints of HDPE pipe in an

environment that is protected from the effects of wind-blown debris, moisture or

inclement weather. This configuration allows for joining of the HDPE pipe string on anall-weather basis thereby assuring optimal productivity at any job site.

Once the fusion joint has been fully cooled and considered complete, the operator in theAMFT vehicle releases the joint and then progresses down the right-of-way picking up

the next joint of HDPE pipe and feeding it into the cab for fusion to the exiting pipe

string. Simultaneously, the completed pipe string exits the rear of the AMFT vehiclefeeding out along the right-of-way as the vehicle progresses forward. The result is a

fusion joined, completed pipe string laid down along the right-of-way adjacent to the

trench and ready for installation.



The AMFT vehicle is the industry’s first attempt to address HDPE pipe fusion as an

integrated step within the overall pipeline construction process. Some specific benefits of the AMFT system are as follows.

• Tracked vehicle design assures mobility in the most demanding pipeline

construction environments.• Climate controlled fusion environment that insures high quality fusion results

despite aggressive weather conditions.

• Unique pipe handling capability minimizes the need for additional costly pipehandling equipment on the job-site during the fusion process

• Standard commercially available butt fusion equipment mounted in-line with

vehicle’s direction of travel

• Proprietary technology provides for quick, uniform removal of heat from the buttfusion joint

• Absolute minimal disturbance of the butt fusion joint during the cooling andremoval process

• Integrated butt fusion data logging of all fusion joints

While it is the combination of each of these benefits that bears a direct relationship on theoverall productivity improvement potential of the AMFT equipment, there are two

specific points that warrant further consideration as to their impact on the overall quality

of the fusion joint produced using this technology. These are: the proprietary heatremoval system and the integrated movement control system. Each of these points will

be discussed briefly as follows.

The AMFT apparatus utilizes proprietary technology to remove heat from the fusion joint

in a uniform controlled fashion. It is important to understand that this unique approach

does not actually cool the joint. Rather a patented apparatus is placed around the fusion joint at the time of cooling. This device then circulates ambient air around the joint toexpedite the removal of heat without affecting the overall integrity of the joint. Again, all

parameters relating to this step in the fusion process are recorded in the AMFT on-board

computer system.

In traditional butt fusion of HDPE pipe, a joint is made within the fusion apparatus and

then allowed to cool to a non-specific temperature at which time it is removed from themachine. The removal process typically entails the pulling of the fused string of pipe out

of the fusion equipment potentially placing considerable stress on the freshly made fusion

joint. Depending on the temperature of the joint at the time that the pipe string is

“pulled” from the fusion equipment, the associated forces may have an affect on thequality of the fusion joint just produced. With AMFT technology, the pipe is not

“pulled” from the fusion apparatus. As each joint is produced and cooled using AMFT

technology, the fusion apparatus is moved out from under the freshly made fusion joint asthe vehicle proceeds along the pipeline right of way. In this way, the resulting stress

imposed on the freshly made fusion joint is minimized to the extent possible as compared

to conventional butt fusion.



TESTING AND TEST RESULTS:

The fusion heat removal system utilized within the AMFT process is, in itself, a unique

evolution in fusion joining technology. As such, testing has been performed to validate

the overall AMFT fusion process and insure that the resulting joint integrity is notaffected in any way.

Hydrostatic testing of fusion joints produced using AMFT technology was undertaken in

2005 in accordance with the requirements of ASTM D2513-04a.(3) Three series of

fusion joints were produced to facilitate testing; a) the first series was conventionalPE3408, b) the second series was conventional PE2406 and c) the final series was

produced from cross-fusions of PE3408 to PE100 piping products. Three specimens

were produced from each series of pipe resulting in a total test regime of 9 specimens.

Fusion conditions for each series of test specimens are detailed in Table 1

Table 1: Fusion Conditions for Each Series of Pipe to be Tested

Series MaterialHeart time,

seconds

Fusion Time,

seconds

Cooling Time,

seconds

I PE3408/PE3408 200 16 360

II PE2406/PE2406 100 16 210

III PE3408/PE100 100 16 210

Each specimen was then placed on hydrostatic test in accordance with ASTM D1598-02

at 80º C and a fiber stress of 670 or 798 psi. The test results are summarized in Table 2which follows.

Table 2: ASTM 1598-02 80º C Testing of Pipe Specimens Produced

with AMFT Technology

Specimen Material OD, inchesStress,

psi

Minimum Time

to Failure, hoursTest Results, hours

I-1/2 PE3408 18.250 670 165 Pass, removed after 170



II-1/2 PE2406 12.733 670 165 Pass, removed after 170

II-3/4 PE2406 12.733 670 165 Pass, removed after 170

II-5/6 PE2406 12.733 670 165 Pass, removed after 170III-1/2 PE3408/PE100 12.750 798 165 Pass, removed after 165

III-3/4 PE3408/PE100 12.750 798 165 Pass, removed after 165

III-5/6 PE3408/PE100 12.750 798 165 Pass, removed after 165

From these results, we see that all specimens produced using the AMFT technologypassed the elevated temperature sustained pressure test of ASTM D2513-04a. Due to test

space limitation, all but one of the specimens was removed from test shortly after



exceeding the minimum number of hours required. The one exception was test specimen

I-5/6 which was allowed to continue under stress until it was removed with over 400hours of test time. All specimens completed or exceeded the recommended test time

without failure and, hence, meet the requirements for sustained pressure testing of the

pipe itself.

Figure 6: Photo of Test Specimens from (left to right) Series III, I and II

DISCUSSION:

The AMFT fusion procedure represents the next evolution in fusion joining of HDPE

pipe. The proprietary technology involved produces a high quality butt fusion joint

shown to meet or exceed the elevated temperature sustained pressure testing requirementsof ASTM D2513 in a consistent manner. It should also be noted that additional

comparative testing was conducted during 2003. These tests of fusion joints produced

with AMFT technology versus those produced with standard butt fusion technologyshowed no difference in performance when tested for tensile strength, tensile elongation

or bend back testing and all test specimens produced using both technologies surpassed

the requirements of Title 49 CFR.(5)

These test results presented in this discussion bear testament to the fact that the

proprietary cooling mechanism associated with AMFT does not affect the integrity of theresulting fusion joint. Obviously, this heat removal mechanism inherent to the AMFT

technology can be directly correlated to time savings at the job site.



However, the tangible benefits of the AMFT are not limited to the time savingsassociated with efficient heat removal from the fusion joint itself. Rather, it is the

deployment of the full AMFT technology at the job-site that results in overall

productivity improvement. Improved pipe handling capability and climate controlled

fusion environment combined with efficient heat removal results in time and cost savingsin the overall pipeline installation project.

In April, 2004, pipe joining productivity measurements were recorded on a major

pipeline construction project in Alberta, Canada. The results are presented in Table 3

below. This data was collected based on an average 8 hour work day, 50 foot HDPE pipe joints, a 50% reduction in the manufacturer’s recommended cooling time for SDR 11 and

a 40% reduction in the manufacturer’s recommend cooling time for SDR 7 and utilizing

all of the AMFT pipe handling and movement capability in open terrain.

Table 3: AMFT Job-Site Productivity Data, April, 2004

Size OD, inches SDR Min Feet per Day Max feet per Day

3.500 11 7600 7900

3.500 7 6500 6900

4.500 11 6500 7000

4.500 7 5700 6200

6.625 11 5500 6100

6.625 7 4700 5300

8.625 11 4300 5100

8.625 7 3800 4400

10.750 11 3600 4200

10.750 7 3400 4000

12.750 11 3100 3600

12.750 7 2600 310016.000 11 2400 2800

16.000 7 2300 2700

18.000 11 2100 2600

18.000 7 1800 2200

20.000 11 1300 1600

20.000 7 1000 1300

AMFT was the only fusion technology deployed on this particular job site thus making adirect comparison to traditional butt fusion in the same project impractical. However,

experience with traditional butt fusion technology in similar size ranges and comparative

terrain suggests that the productivity improvement (defined as feet of pipe joined per day)afforded by AMFT on this particular project is somewhere in the range of 35-50%depending the specific size of pipe being joined at the job site.

The AMFT fusion technology can be deployed on nearly any job-site attesting to itsversatility. However, as with any project, there is an appropriate tool for every job.

AMFT is another of those tools for effectively joining HDPE at the job-site. It should be

noted, that the AMFT technology is best-suited to net significant productivity



improvements on projects characterized by open terrain which afford long stretches of

trench or right-of-way access.

SUMMARY AND CONCLUSION:

This paper has introduced a new HDPE pipe joining technology knows as automated

mobile fusion technology or AMFT. Through this discussion, this new technology hasbeen addressed as yet another evolution in the predominant means by which to join

HDPE piping systems. With two notable exceptions, this technology does not deviate

from the traditional butt fusion protocol prevalent throughout North America. These twoexceptions are the automated removal of heat during the cooling cycle of the butt fusion

process and the movement of the completed fusion joint out of the fusion apparatus.

We have shown that these two features pose no detriment to the integrity of the fusion joint produced using this technology and data was presented to verify that joints made

using this technology surpass the elevated temperature testing requirements of ASTMD2513. There too, it was shown that these test results apply across the various pipematerials designations, PE2406, PE3408 and PE100 (soon to be PE4710 in North

America).

Finally, it was shown that these advancements in the fusion joining process combined

with the climate controlled fusion environment and pipe handling capability of the AMFT

apparatus pose tremendous potential in advancing job-site productivity when installing

HDPE pipe. From this discussion, it is clear that automated mobile fusion technologywill play an increasingly visible role in the design, installation and overall economics of

HDPE piping systems.

REFERENCES:

1) “Chapter 9, Polyethylene Joining Procedures”, Handbook of Polyethylene Pipe,

Plastics Pipe Institute, Washington DC, 2006.

2) PPI TR-33/2005, “Generic Butt Fusion Joining Procedure for Filed Joining of

Polyethylene Pipe”, Plastics Pipe Institute, Washington DC, 2005

3) ASTM D2513-2004a, “Standard Specification for Thermoplastic Gas Pressure

Pipe, Tubing and Fittings”, American Society for Testing and Materials, WestConshohocken, PA, 2004.

4) ASTM D1598, “Standard Test Method for Time-to-Failure of Plastic Pipe Uner

Constant Internal Pressure”, American Society for Testing and Materials, WestConshohocken, PA, 2002.

5) Title 49, Part 192, “Transportation of Natural and Other Gas Pipeline: Minimum

Federal Safety Standards”, Department of Transportation, Office of PipelineSafety

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Analytical Testing of Advanced Butt Fusion Technology

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