Important Parameters in Electrofusion Welding Process of Polymer Pipes: A Review

Electrofusion is among several techniques to join polymer pipes using special fittings. In electrofusion, polymer pipes and fittings are joined together through wires that are installed in their structures. The main difference between the two techniques of common heat fusion and electrofusion is in heat transfer mechanism. In heat fusion, a heating device is used to melt interfaces of the pipes and polymer fitting. In electrofusion, there is internal melting through a conductive substance inside the weld interface or melting by a conductive polymer. The heat is produced through electric current contacting conductive materials installed inside the fittings. In order to have desirable materials and useful products, design and installation is based on proper joints having passed good welding testing conditions. Methods of welding and joining are different and depend on parameters such as the type of polymer pipe, polymer structural changes, requirements imposed on interior or external pressure of the pipe, decreasing leakage, prohibition of strokes and longitudinal impact loads, performance and operational conditions, construction and installation operations and types of products that have to be joined together. In this paper a survey of electrofusion process on dimensional strength, parameters accounted for in joint's integrity and stability, mechanisms related to macromolecular magnitude of joint formation, diffusion of molecules in polymer structures, and formation or rupture of chemical bonds through different experimental and computational methods are reviewed based on researcher's findings.