The fast and practical testing method and qualification judgment of PE pipe hot melt connection and electrofusion connection welded junction joint quality is also a bottleneck of PE pipe construction at present.
Taking hot-melt connection as an example, the current inspection method is to inspect the quality by visually inspecting the appearance of the welded junction ring. Although some problems can be found through the appearance of the welded junction ring, some internal problems cannot be reflected from the surface, such as "false welding". The appearance of "false welding" is almost the same as the qualified appearance, but the long-term strength cannot be guaranteed, In a gas company, "false welding" was formed due to the fusion of PE pipe, and the foundation of gas pipeline was damaged during the construction of other pipelines. Under the unbalanced external force, the gas pipeline was squeezed and cracked, resulting in a major leakage accident. In terms of electrofusion connection, it is incomplete and inaccurate to judge the quality of welding only by whether the observation hole on the final electrofusion pipe is ejected or not. The observation hole is only a basis for judging the welding effect. The final quality of electrofusion welded joints mainly depends on strict control during operation. Therefore, it is of great significance to develop a rapid and practical testing method for the quality of polyethylene (PE) pressure pipe joints to ensure the project quality.
As far as the PE pipe connection construction is concerned, although the operation is simple and easy to master, the operation steps, that is, the process control of the operation, must be strictly controlled regardless of the operation process of the hot melt connection and the electric melt connection, rather than relying solely on the final crater to determine the qualified joint quality. Taking hot-melt welding as an example, temperature, time and pressure are the three most important factors in the welding process. As PE pipe hot-melt welding is very vulnerable to environmental changes and human operation factors, there is no uniform setting in the world, However, in some countries where PE pipes were used earlier, a relatively complete and mature set of operating procedures and calculation methods for parameter setting have been formed. In many PE pipe projects in China, the setting of three important factors is generally provided by polyethylene (PE) manufacturers, so there are large differences.
