The steel mesh skeleton plastic composite pipe (hereinafter referred to as composite pipe) is a new type of composite pipe with independent intellectual property rights. This kind of composite pipe uses coated high-strength steel wire to wind and strengthen the existing pure PE pipe, so that the nominal pressure of the pipe can easily reach more than 5MPa (diameter ≤ φ 200), 2MPa (diameter ≤ φ 400), and the pipe wall thickness is lower than that of pure PE pipe. This kind of composite pipe can make the recognized PE pipe more powerful and will bring good economic benefits to the society. This article briefly introduces the technology and application of this new type of pipe.
The structure and production process of the steel mesh skeleton plastic composite pipe 1. Pipe structure characteristics The structural characteristics of the steel mesh skeleton plastic (polyethylene) composite pipe are that there are two or more layers of steel mesh reinforcement layer formed by winding between the inner pipe wall and the outer pipe wall.
The steel wire for reinforcement is high strength coated steel wire. Before winding, the outer layer of the steel wire is covered with a coating with hot-melt bonding property and water blocking effect. After winding on the core pipe, it is heated, extruded and coated by the intermediate binding layer, and extruded and coated by the outer PE layer to ensure that the hot melt bonding between the high-strength steel wire and the inner and outer PE layers is integrated. Thus, composite pipes with excellent performance can be obtained. The cladding layer coated on the high-strength steel wire is a high-performance bonding material, which belongs to HDPE modified material. It can be fused with HDPE under heating conditions. At the same time, its polar bond has very strong bonding performance with steel (200N/25mm, ASTMD903).
This high-performance adhesive is a new product of a famous international company, and has been widely used as a steel HDPE interface material in China's West to East Gas Pipeline Project. Because this kind of pipe effectively solves the problem of steel PE interface, it overcomes the defect of common steel wire composite pipe of direct extrusion composite type - there is no connection factor between steel wire and plastic, and the plastic just mechanically encloses the steel wire in it. The temperature stress and internal pressure ring stress during storage and use make the metal plastic interface appear gaps, When the pipe end sealing is not good or the pipe opening sealing is not good, it will cause water channeling between layers, resulting in damage of the pipe under low internal pressure.
It is precisely because of the solution of the problem of steel PE interface that the method of strengthening PE with steel has been further developed and improved. The application of steel PE composite pipes manufactured by new methods in engineering will become more convenient and more widely used. For example, the end sealing process of pipes with extremely strict requirements has become convenient and reliable; Opening and branching on the pipe wall becomes easier from very difficult; The sealing process after opening on the pipe wall has also changed from difficult and complex to simple and reliable.
At the same time, because the amount of metal in this composite pipe per meter of pipe is much less than that in the common steel wire and steel plate reinforced PE composite pipe, and the outer PE is thick, the heat absorption of the enhanced metal layer is reduced when the pipe is electrically fused, so the fusion performance of the pipe and the electrothermal fusion pipe fittings is greatly improved, almost equal to that of the pure PE pipe.