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Improving the Quality of PE Jointing
No Dig Roadshow, Reading, 22nd June 2017
Mike Shepherd
What do we ALL want?
We want a welded polyethylene pipe system that when installed gives over 100 years reliable lifetime
How do we achieve this?
• By using a high toughness quality pipes and fittings that are fit for purpose
• By using the right fusion jointing equipment• By using a rigorous jointing specification• By employing well trained, competent personnel• By exercising rigorous quality control• By carrying out pressure testing on all installations
Materials
• PE pipes and fittings are covered by the excellent BS EN 12201 suite of standards
• This covers both water and sewer pressure pipes• However, two areas of weakness:
• Ovality, especially for coiled pipes• Spigot lengths on plain ended fittings
Fusion jointing equipment
• Requirements are covered in the latest Water Industry Specification WIS 4‐32‐08 v4
• Butt fusion machines to be fully automatic – though semi‐automatic allowed for larger pipes (>630mmOD)
• Mechanical scrapers to be used for EF joint preparation
• Robust re‐rounding and alignment clamps to be used for EF jointing
• Data logging of welding parameters with operator ID
Fusion jointing specification
• The latest version of WIS 4‐32‐08 ‐ v4 ‐ has been produced by experts from the water industry, the BPF Pipes Group, pipe and fitting manufacturers, equipment manufacturers, contractors and test houses.
• As well as the more stringent equipment requirements, there are a number of significant changes from the previous version
Fusion jointing specification ‐Butt Fusion
• Following extensive testing, an equation to calculate cooling times for butt fusion has been derived and is given in the standard
• The range of diameters covered has been extended to 1200mm OD
• Cooling times are calculated for cooling to 80o C• All cooling is to take place in clamps
Fusion jointing specification –Electrofusion
• Greater emphasis placed on joint preparation, especially the avoidance of contamination
• Greater emphasis placed on joint clamping and pipe re‐rounding
• Responsibility placed on EF fitting manufacturers to specify fusion and cooling times and also any special requirements
Fusion jointing specification –Testing
• The testing methods and requirements for site made joints have now been aligned with the type tests set out in BS EN 12201
• The “talc contamination test” has been removed from the document
• Research is now being carried out to develop a shear test for EF joints which will be included in the next revision
Operative training
• Most PE pipe and fitting suppliers offer in house training on installation and jointing. They also offer “tool box” talks on site
• Some procurement contracts require suppliers provide free training courses and materials
• Some contractors have put in place their own in‐house PE welder training and accreditation
• All these are good things
Operative training
• Although there is an NVQ module on PE jointing, it’s not mandatory and is for life
• The water industry, together with training houses, pope and fittings manufacturers and the BPF Pipes Group have written a draft WIS for the certification of training for fusion jointers
• Originally intended to be third party certified but there have been some hold ups. Water industry and BPF Pipes Group currently trying to resolve.
Operative training
• In brief, the WIS proposes that training courses should cover both theoretical and practical knowledge of PE fusion procedures with assessment
• That practical training should replicate site conditions
• That certification is time limited to three years• That training and assessment for supervisors should be the same as for operatives
Operative training
• Theoretical knowledge will be assessed via a written exam of about 20 questions containing two or three “must know” questions and covering key aspects of equipment and procedures.
• The training will have a number of different modules covering the various diameter ranges
• Operatives must have the current smaller diameter range accreditations to obtain the larger diameter ones.
Quality Control
• A number of contractors already are operating their own QA systems with testing regimes for site made joints, recording systems of joints made, operative ID etc. This is now a requirement of the WIS
• WIS 4‐32‐08 requires that installers now have PE fusion jointing as part of their ISO 9001 QA systems
• Some contractors are also using intelligent fusion machines and EF boxes with third party inspectors
Quality Control
• The WIS now has a requirement for calibration checks to be carried out and recorded
• At present, there is no requirement for NDT testing of welds as there are not yet any quantative methods of analysis.
• The “twist” or “bend back” test on butt fusion weld bead is still included as a quick QA test, with a photo to show how it should be done
Quality Control
Failed bead “twist” test
Pressure testing
• The Water Industry Information and Guidance Note IGN 4‐01‐03 v2 has recently been published
• It covers all pipe materials• The “pass” criteria are those set out in BS EN 805• The System test pressure requirements are those set out in BS EN 805
• There is a “two minute” test for EF service connections
Pressure testing
• There is also a “ten minute” test intended for use with coiled pipe or short pipe strings used in trenchless installations where there is a need to get customers back into supply the same day
Typical Mains Renewal test graph showing the pressure increasing with high flows, the flow reducing as the test pressure is reached and then decreasing as
the rate of creep slows
Mains Renewal test graph indicating a leak. Pressure fluctuates from the test pressure and flow rate is high and does not reduce over the duration of the test
Getting the documents
• All WIS and IGN documents are free downloads and can be obtained from:http://www.water.org.uk/publications/WIS‐IGN
Thank You
Any Questions?