Assembly : Methods

PE pipe can be assembled into a pipeline network by means of fusion or mechanical assembly techniques. Fusion of PE pipe and fittings may be by either Butt Fusion or Electrofusion. Other techniques are available (sockt fusion and induction fusion) but are not commonly available and will not be considered here.  Guidance on the various methods of jointing PE pipes can be found at:  www.teppfa.eu/media/guides/filter/utilities/ Fusion Fusion comprises applying heat and pressure for a specified...

Electrofusion Jointing Electrofusion is a simple method of joining PE pipes in circumstances where butt fusion is not practicable. In addition to the jointing of line pipes using couplings this can be where fittings such as valves, elbows, and tees must be added. Prefabricated fittings are used, incorporating an electrical heating coil which melts the polyethylene of both the fitting and the pipe, causing them to fuse together when the material cools. How does electrofusion work Diagram of...

Butt fusion is a thermofusion process  Butt fusion is a process by which the square cut ends of two pipes or fittings of the same diameter, wall thickness and material type (PE80 or PE100), are fused together. It can be used to weld together pipes of 90 mm OD (Outside Diameter) and higher. Smaller diameters are normally fusion welded using electrofusion joints, though some technical specifications do allow pipe of down to 63 mm OD to be butt fusion welded in carefully controlled...

Mechanical assembly requires the use of fittings, generally working on the compression principle, to join different materials together. It is most commonly used with PE for joining the PE to a pipe or fitting of a different material, or in circumstances where fusion is not feasible. Larger diameter mechanical fittings can include a stiffener which is placed inside the pipe or fitting to ensure stability when the fitting is compressed, but these are generally not required in smaller diameter...

Butt fusion Butt fusion can be used for jointing pipes and fittings of 90 mm OD (Outside Diameter) and larger. Some technical specifications allow the use of butt fusion down to 63 mm OD in carefully controlled conditions. Butt fusion jointing is equally suited to both  coiled and straight pipe lengths. The pipe clamps that form part of the welding machine are normally sufficient to deal with any ovality that may have occurred during storage or transportation. Only pipes and fittings of the...

To ensure that good quality butt fusion joints are made it is essential that the correct equipment is used. The welding machine and associated equipment used must be robust enough to handle the size and weight of the pipe to be joined. It is essential that the correct pressures be maintained on the pipe ends during each phase of the procedure. To achieve this only hydraulically operated equipment should be used. Many modern butt fusion machines include data logging facilities that record...

Butt fusion It is possible to  butt fuse pipes and fittings of different grades and SDR (Standard Dimensional Ratio), but this is very rarely undertaken and should only be carried out under controlled conditions and in accordance with the instructions of the pipe and/or fitting suppliers. Where there are pipes of the same grade, e.g. PE100, but different wall thicknesses, the preferred approach is to machine down the end of the thicker wall pipe or fitting using a lathe or similar machine so...

Butt fusion Butt fusion procedures require the application of temperature and pressure over time to the mated ends of the pipes or fittings. The procedures developed in different European countries are all similar in principle but different in detail. All have been tested and all produce satisfactory joints when the procedures are followed correctly. The differences between the procedures are in the level of pressure to be applied, the time for which it is to be applied and the temperature of...

All operatives making use of butt fusion and electrofusion jointing systems for PE pipes and fittings should have undergone a training course and, upon passing an exam, be certified as an approved operator and issued with an operator’s badge. In general such training courses and their assessment should comply with the requirements of ISO/TR 19480:2005. The badge must conform with  ISO 12176-3:2001  and in most countries the badge has a validation period of 1 to 2 years after which it must be...

Traceability is an integral part of modern quality assurance systems used for PE pipe networks. The systems available, the implementation of which is mandatory at many end-user organisations, enable tracing through the whole process from the resin batch at the PE producer, through pipe extrusion, the utility company and the installation contractor's operations. If fully implemented correctly, all installations can be traced all the way back to the resin batch from which the pipes or fittings...

Different methods of testing finished fusion joints in PE pipes have been developed in different countries. They vary in their approach to the question of how a joint should be tested and to date a standard system across Europe has not been agreed upon. Whilst ultrasonic non-destructive testing (NDT) of welded joints is widely used on steel pipelines, the development required to use the technique on plastic pipes has taken much longer. There are however now several organisations that offer...