Integration, Shut-Off and Repair Technology for PE Pipe Systems [PE]

„No welding if media escapes”, “residual water problems” and “need for space” are phrases invariably used when repairs and integration to PE pipe systems is the topic of conversation. Quite rightly so, because clean fusion zone surfaces are an important prerequisite for a strong, homogenous PE fusion jointing. Below, you will find attempts at problem solving for the reconnection of separated pipes, the repair of local damage as well as the integration of tees into pressure pipes, in a practical way and in line with site practices. In the Seventies, when the gas supply network was beginning to be extended throughout Europe, the service focused especially on one pipe material : polyethylene. There were and still are enough good reasons for this choice : no corrosion, great flexibility, low weight, good economy and above all a connection technology tailor-made to the material due to the fusibility of the material. The butt welding procedure, and even more so the electro fusion procedure, have proved themselves to be both reliable and suitable for use on site. Through the homogenous fusion of PE fittings a joint is created which exceeds the longevity and strength of the actual pipe : the connection is no longer the “weakest link” in a pipe, on the contrary it provides a strengthening of the pipe. Polyethylene became increasingly interesting to the water supply industry due to further development of material types aiming for more strength but also greater resistance to the demands made on pipes in underground pipe installation, as for example resistance to notches. Pipe joints up to d 710 are made possible through electro fusion couplers and fittings, e.g. T-pieces or elbows up to d225 further improve the economical application of this technology. However, it must not be forgotten that, in spite of excellent features and constant improvements of polyethylene, repairs to pipe systems are inevitable and will be on the increase - due to more widespread application. Causes for damage may be ground movement, caused by underground construction work, or digger work. Causes for necessary repairs may also be found in planning, installation and material faults. In order to be able to carry out repairs and integration of T´s on existing supply pipe systems, the appropriate procedures must be available. The following will attempt to show some of these options. Butt welding needs to be excluded up to a point from the areas “repair and integration technology” due to the procedure. On the other hand, electro fusion technique offer interesting applications for this type of use. In order to achieve a high electro fusion jointing quality, the work must be prepared and carried out carefully and above all to a high degree of cleanliness. Escaping medium is not permissible at a repair site. As strict safety measures are a priority with gas, faulty shut-off devices can affect quality in the water supply industry due to residual water flowing out. It is therefore absolutely vital to prevent the medium escaping or flowing out in the fusion zone during the fusion process.