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Why AIM33 for EF Why AIM33 for EF joints of PE pipe?joints of PE pipe?

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Polyethylene (PE) is Polyethylene (PE) is good material for gas good material for gas piping.piping. M.Fujikake, M.Fukumura and K. Kitao, M.Fujikake, M.Fukumura and K. Kitao,

“Analysis of the electrofusion joining process “Analysis of the electrofusion joining process in polyethylene gas piping”, Computer & in polyethylene gas piping”, Computer & Structures Vol. 64, No.5/6. Pp.939-948, 1997Structures Vol. 64, No.5/6. Pp.939-948, 1997

– PE hardly corrodes and is very flexible, so it is PE hardly corrodes and is very flexible, so it is safe from earthquakes and a ground safe from earthquakes and a ground subsidence. subsidence.

– It is also light and easily constructed.It is also light and easily constructed.

Many others agree!Many others agree!

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For the use of EF joint.For the use of EF joint.

M.Fujikake, M.Fukumura and K. Kitao, “Analysis of M.Fujikake, M.Fukumura and K. Kitao, “Analysis of the electrofusion joining process in polyethylene gas the electrofusion joining process in polyethylene gas piping”, Computer & Structures Vol. 64, No.5/6. piping”, Computer & Structures Vol. 64, No.5/6. Pp.939-948, 1997 Pp.939-948, 1997

– However, as for the large size PE pipes, there remains a However, as for the large size PE pipes, there remains a fundamental barrier to the wide usage of the EF joining fundamental barrier to the wide usage of the EF joining technique because of the absence of quantitative technique because of the absence of quantitative performance data and reliable computational models.performance data and reliable computational models.

– The influences of power input, heating time and clearance The influences of power input, heating time and clearance size on the quality of the joints had been carried out by size on the quality of the joints had been carried out by previous researchers.previous researchers.

– The quality will be heavily dependent on the temperature The quality will be heavily dependent on the temperature and the pressure at the interface region during the joining and the pressure at the interface region during the joining process.process.

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To make EF joints, we To make EF joints, we needneed To make EF joints, we needTo make EF joints, we need

– a suitable range of heating time.a suitable range of heating time.– a suitable range of interface temperature.a suitable range of interface temperature.– a suitable range of interface pressure.a suitable range of interface pressure.– a suitable cool-down time.a suitable cool-down time.– a good preparation of the outer surface and inner a good preparation of the outer surface and inner

surface of pipe.surface of pipe.– a good alignment.a good alignment.– a welding equipment that can control heating time, a welding equipment that can control heating time,

interface temperature, and interface pressure.interface temperature, and interface pressure.

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To improve joining To improve joining processprocess Jeremy Bowman (Fusion Group Plc), “A review of Jeremy Bowman (Fusion Group Plc), “A review of

the electrofusion joining process for polyethylene the electrofusion joining process for polyethylene pipe system”, Polymer Engineering and Science, pipe system”, Polymer Engineering and Science, April 1997, Vol.37, No.4April 1997, Vol.37, No.4

– User of EF fittings can gain guidance on the essential site User of EF fittings can gain guidance on the essential site practices from their fittings suppliers.practices from their fittings suppliers.

Up to date, people focused to improve joining Up to date, people focused to improve joining process to make good EF joints.process to make good EF joints.

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Is the welding Is the welding equipment intelligent equipment intelligent enough?enough? The present welding equipment indicate electric The present welding equipment indicate electric

power supplied (fusion time).power supplied (fusion time).

Can the present welding equipment indicate that Can the present welding equipment indicate that – there are no flaws?there are no flaws?– the original PE piping and coupler are defect free?the original PE piping and coupler are defect free?– the EF coupler is made well?the EF coupler is made well?– the interface pressure is good?the interface pressure is good?– there are no contamination at the fusion interface?there are no contamination at the fusion interface?– the welding equipment itself is working properly?the welding equipment itself is working properly?– welding operators are not making mistake?welding operators are not making mistake?

We can not rely on the welding equipment’s We can not rely on the welding equipment’s performance for expected life time and safety.performance for expected life time and safety.

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Is the pressure test Is the pressure test assure joint quality?assure joint quality?

Pressure test is an indirect method for leakage test. Can the pressure test assure joint quality for expected life time of

EF joints?

We need direct inspection methods such as nondestructive testing (NDT).

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Factors causing failure Factors causing failure by EF joining processby EF joining process

Factors on human errors; Factors on human errors; cleaning, clamping, cooling time, operation of cleaning, clamping, cooling time, operation of welding equipment, gap between fitting and pipewelding equipment, gap between fitting and pipe

Factors on equipment errors; Factors on equipment errors; equipment performance variation, degradation of equipment performance variation, degradation of equipment, frequency of electricity, input voltage, equipment, frequency of electricity, input voltage, excessive length of electric cable, capacity of excessive length of electric cable, capacity of portable power generator at field, loose of portable power generator at field, loose of connectors for fitting, contamination of connectorsconnectors for fitting, contamination of connectors

Factors on environment; Factors on environment; temperature, rain, dusttemperature, rain, dust

Factors on installation; Factors on installation; bendingbending

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Factors causing failure Factors causing failure by manufacturing by manufacturing processprocess Factors on EF fitting; Factors on EF fitting;

errors on implanting resistance heating wires, errors on implanting resistance heating wires, lamination between wire area and fitting, flaws lamination between wire area and fitting, flaws such as void inclusion and cracks, size variation, such as void inclusion and cracks, size variation, contamination of terminal pin, inner surface contamination of terminal pin, inner surface contamination, geometrical deformation by contamination, geometrical deformation by environment, storage or/and transportation environment, storage or/and transportation

Factors on piping; Factors on piping; flaws such as void inclusion and cracks, size flaws such as void inclusion and cracks, size variation, outer surface contamination, variation, outer surface contamination, geometrical deformation by environment, geometrical deformation by environment, storage or/and transportationstorage or/and transportation

Factors on materialFactors on material

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Factors causing failure in Factors causing failure in serviceservice

Internal gas pressure loadingInternal gas pressure loading

Bending stressBending stress

FatigueFatigue

CrackingCracking

Ground movement such as earth quakes and a ground Ground movement such as earth quakes and a ground

subsidencesubsidence

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Need to ensure Need to ensure integrity of EF jointsintegrity of EF joints Jeremy Bowman (Fusion Group Plc), “A review of Jeremy Bowman (Fusion Group Plc), “A review of

the electrofusion joining process for the electrofusion joining process for polyethylene pipe system”, Polymer Engineering polyethylene pipe system”, Polymer Engineering and Science, April 1997, Vol.37, No.4and Science, April 1997, Vol.37, No.4– Significant loads are applied for extended periods of time. Significant loads are applied for extended periods of time.

(PE pipe systems must sustain pipe hoop stresses of (PE pipe systems must sustain pipe hoop stresses of 8MPa 8MPa for a typical design life of 50 years.)for a typical design life of 50 years.)

– The long term strength and integrity depends, in part, on the The long term strength and integrity depends, in part, on the strength of the fusion joints.strength of the fusion joints.

– Since many of these system carry fuel gas, failure rates at Since many of these system carry fuel gas, failure rates at joints must tend to zero.joints must tend to zero.

It is essential to have direct It is essential to have direct inspection method such as inspection method such as nondestructive testing (NDT).nondestructive testing (NDT).

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The missing factor in The missing factor in EF joining systemEF joining system T.H. Striplin, (McElroy) “Non-Destructive T.H. Striplin, (McElroy) “Non-Destructive

Testing of Electrofusion Joints and Large Testing of Electrofusion Joints and Large Diameter Gas Pipes” Diameter Gas Pipes”

– For years, the pipeline industry has had a means of For years, the pipeline industry has had a means of non-destructive testing the welded joints that they non-destructive testing the welded joints that they installed. When plastics arrived on the scene, the installed. When plastics arrived on the scene, the rules changed. Since there was no valid means of rules changed. Since there was no valid means of inspecting fuse welded joints, the practice was inspecting fuse welded joints, the practice was discarded. …… Why not have the same tools discarded. …… Why not have the same tools available for PE pipe joints as are available for steel?available for PE pipe joints as are available for steel?

– At any rate, the missing factor in the EF joining At any rate, the missing factor in the EF joining system is the lack of a method for NDT.system is the lack of a method for NDT.

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NDT needs for EF NDT needs for EF joints (1)joints (1) T.H. Striplin, (McElroy) “Non-Destructive T.H. Striplin, (McElroy) “Non-Destructive

Testing of Electrofusion Joints and Large Testing of Electrofusion Joints and Large Diameter Gas Pipes” Diameter Gas Pipes”

– Although the number of EF joint failures have Although the number of EF joint failures have dropped significantly, there is evidence that there dropped significantly, there is evidence that there is potential for EF joint failures as with any joining is potential for EF joint failures as with any joining method. method.

– While EF has been sold as an easier method of While EF has been sold as an easier method of joining, it could be argued that it is as operator joining, it could be argued that it is as operator dependent and perhaps less trouble free than dependent and perhaps less trouble free than other methods.other methods.

– They were experiencing problems with failure They were experiencing problems with failure primarily due to contamination.primarily due to contamination.

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NDT needs for EF NDT needs for EF joints (2)joints (2) T.Kitaoka and J.Furukawa, (Osaka Gas Co., T.Kitaoka and J.Furukawa, (Osaka Gas Co.,

Ltd.) “Development of electrofusion interface Ltd.) “Development of electrofusion interface ultrasonic inspection technique, contributing ultrasonic inspection technique, contributing to construction of highly reliable PE piping” to construction of highly reliable PE piping” – Strength of EF joint decreased when some Strength of EF joint decreased when some

foreign substances like water, mud, sand, and foreign substances like water, mud, sand, and ect. was included on the fusion interface.ect. was included on the fusion interface.

– Development has been awaited of a Development has been awaited of a nondestructive joint inspection technique nondestructive joint inspection technique which can reliably detect any defective joint which can reliably detect any defective joint immediately after PE pipes are fusion-welded.immediately after PE pipes are fusion-welded.

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NDT needs for PE piping NDT needs for PE piping system (1)system (1)

G.J.P. ter Horst, F.G.E.B Weyn, R.J.M.Hermkens,G.J.P. ter Horst, F.G.E.B Weyn, R.J.M.Hermkens,(GASTEC N.V., The Netherlands) “Ultrasonic inspection (GASTEC N.V., The Netherlands) “Ultrasonic inspection of butt-fused PE-joints” (A project funded by of butt-fused PE-joints” (A project funded by EnergieNed, the Dutch branche organization for the EnergieNed, the Dutch branche organization for the energy distribution companies.)energy distribution companies.)– For a long time the energy distribution companies in the For a long time the energy distribution companies in the

Netherlands have expressed their need for ways of effectively Netherlands have expressed their need for ways of effectively assessing the quality of field-installed PE-pipe systems to assessing the quality of field-installed PE-pipe systems to prove integrity and reduce maintenance and repair costs. prove integrity and reduce maintenance and repair costs.

– This becomes especially important with the increased used of This becomes especially important with the increased used of these PE-systems for higher pressures. (In these higher these PE-systems for higher pressures. (In these higher pressure systems, x-rays inspections are done as quality pressure systems, x-rays inspections are done as quality

control on the steel pipe welds.)control on the steel pipe welds.)

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NDT need for PE piping NDT need for PE piping system (2)system (2) I.J.Munns and G.A.Georgiou, (TWI), “Ultrasonic I.J.Munns and G.A.Georgiou, (TWI), “Ultrasonic

and Radiographic NDT of butt fusion welds in and Radiographic NDT of butt fusion welds in polyethylene pipe”polyethylene pipe”– As new polyethylene materials are introduced and As new polyethylene materials are introduced and

increased demands are placed on existing increased demands are placed on existing polyethylene materials, there is an additional need polyethylene materials, there is an additional need to monitor quality through reliable non-destructive to monitor quality through reliable non-destructive testing (NDT) methods.testing (NDT) methods.

– At one stage a guideline standard (ASTM F600-78) At one stage a guideline standard (ASTM F600-78) for the manual ultrasonic inspection of butt fusion for the manual ultrasonic inspection of butt fusion welds in polyethylene pipe was introduced. welds in polyethylene pipe was introduced. Unfortunately, the results obtained using this Unfortunately, the results obtained using this standard were so heavily dependent upon the skill of standard were so heavily dependent upon the skill of the operator that it was withdrawn in 1991.the operator that it was withdrawn in 1991.

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Previous NDT study for Previous NDT study for butt jointsbutt joints Helge Petersen (Natugas Syd I/S, Denmark) Helge Petersen (Natugas Syd I/S, Denmark)

and T.H. Striplin (McElroy), “Examination of and T.H. Striplin (McElroy), “Examination of American and Danish butt fusion joints and American and Danish butt fusion joints and test methods in thermoplastics material”, Ref: test methods in thermoplastics material”, Ref: 95612/HP/md/bd, August 199595612/HP/md/bd, August 1995– Acoustic Resonance Technique method that was Acoustic Resonance Technique method that was

developed by Naturgas Syd in cooperation with the developed by Naturgas Syd in cooperation with the FORCE Institutes. (Basically, the idea of the method FORCE Institutes. (Basically, the idea of the method is to measure the attenuation of the transmitted is to measure the attenuation of the transmitted signal as a function of time)signal as a function of time)

– McElroy Test Procedures, /ULTRA-Mc/, (Pitch-catch McElroy Test Procedures, /ULTRA-Mc/, (Pitch-catch and Pulse-echo with the S/W that goes through a and Pulse-echo with the S/W that goes through a decision tree and using the values from some of the decision tree and using the values from some of the 12 features)12 features)

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PE system needs NDT !PE system needs NDT !

PE system needs NDT for both pre-service and in-PE system needs NDT for both pre-service and in-service nondestructive testingservice nondestructive testing

NDT is essential especially for fusion joints such as NDT is essential especially for fusion joints such as butt, EF, and saddle joints.butt, EF, and saddle joints.

Pipes with large diameter needs NDT.Pipes with large diameter needs NDT.

Ball valve need NDT.Ball valve need NDT.

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Nondestructive testing in Nondestructive testing in PE systemPE system NDT will increase integrity and service life.NDT will increase integrity and service life. NDT will save money by reducing maintenance and NDT will save money by reducing maintenance and

repair cost.repair cost. NDT is strongly recommended to prevent man-made-NDT is strongly recommended to prevent man-made-

disaster by gas leakage.disaster by gas leakage. NDT will help research for the development of the PE NDT will help research for the development of the PE

structures.structures.

NDT should be included in the EF joining process to NDT should be included in the EF joining process to complete the quality control system for PE pipe complete the quality control system for PE pipe installation.installation.

NDT should be considered for the maintenance for the NDT should be considered for the maintenance for the suspected positions of buried piping.suspected positions of buried piping.

NDT should be considered to evaluate remaining life NDT should be considered to evaluate remaining life time estimationtime estimation

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Previous NDT studies for Previous NDT studies for EF jointsEF joints T.H. Striplin, (McElroy) --- Tradition A-scan T.H. Striplin, (McElroy) --- Tradition A-scan

methodmethodIt is possible to detect some contaminations in EF It is possible to detect some contaminations in EF joints. However, a more extensive project must be joints. However, a more extensive project must be carried out to provide the true capability.carried out to provide the true capability.

T.Kitaoka and J.Furukawa, (Osaka Gas Co., Ltd.) T.Kitaoka and J.Furukawa, (Osaka Gas Co., Ltd.) --- Traditional B-scan--- Traditional B-scan

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Innovative Nondestructive Innovative Nondestructive Evaluation System – AIM33 Evaluation System – AIM33

In 2003, new NDT methods for PE pipe system are In 2003, new NDT methods for PE pipe system are developed by INDE System Co., Ltd in cooperation with developed by INDE System Co., Ltd in cooperation with Korea Gas Corporation.Korea Gas Corporation.

The unique capability of the AIM33 system allows for The unique capability of the AIM33 system allows for precise examination of the EF joint by obtaining real time precise examination of the EF joint by obtaining real time ultrasonic images of the cross section of the EF joints.ultrasonic images of the cross section of the EF joints.

AIM33 overcome a lot of hinders that were introduced by AIM33 overcome a lot of hinders that were introduced by previous NDT methods.previous NDT methods.

AIM33 is easy to use in real field as well as lab.AIM33 is easy to use in real field as well as lab.

Normal fitter can operate AIM33 with a few hours of Normal fitter can operate AIM33 with a few hours of training. training.

Inspection results are provided by on-site real time images Inspection results are provided by on-site real time images so that there are many functions available.so that there are many functions available.