During use, partial corrosion of PE pipes may occur due to the corrosive effect of the materials used. And during the corresponding construction and repair, some methods need to be used to maintain the usage of PE pipes and prolong their effectiveness.
If the PE pipe is used to repair some corroded sections, it also needs to be connected to steel or cast iron pipes. During the construction process, after the PE lining pipe is inserted into the pipeline and round, flange crimping can be used, or hot melt welding can be used to connect its end to the repaired pipeline. Flange crimping is the process of first welding a steel flange to the pipe end, then heating and flanging a PE liner pipe at the steel flange mouth. The flipped edge is attached to the sealing surface of the flange, and then the two steel flanges are bolted together. This method is generally used for low-pressure pipelines. Hot melt welding is the process of pre wrapping electric heating wires around electric heating fittings. When connecting PE lining pipes, the electric heating wires are heated to melt the fittings and PE lining pipes simultaneously. After cooling, the two are fused together to achieve the purpose of connection and sealing.
And now PE pipes belong to thermoplastic materials and can only be melted by hot melt. Its principle is to heat the two surfaces to be connected to reach the melting temperature, and then bring the two surfaces into contact and melt them together by applying pressure. The purpose of applying pressure to PE pipes is to make the melted material flow, thereby achieving melting and mixing and making the interface disappear, that is, completing the hot melt connection. Hot melt connections include butt fusion, socket fusion, electric heating fusion, and saddle type fusion. Regardless of the connection method used, specialized connection tools should be matched to control the welding quality and heating process, so as to ensure that the interface strength is greater than the base material strength.
For the protection of the coupling connection in actual repair construction, it is not enough to only insert the PE pipe. The part where the two pipes are connected should also be protected to achieve complete anti-corrosion of the pipeline system, and a good lining pipe should be able to withstand repeated disassembly. The connecting ends of the lining pipe and the middle section of the coupling are prone to corrosion, and surface coating or chemical plating techniques are difficult to meet the requirements of repeated disassembly on the construction site. Therefore, protecting the joint parts of the two pipes is a very important part.
The main method for repairing PE pipes during construction is through heating treatment, which connects the two surfaces together to achieve the desired repair effect.