External expanding seamless hot-melt connection method for large-diameter steel-plastic composite pressure pipe

Abstract

The invention discloses an external expanding seamless hot-melt connection method for a large-diameter steel-plastic composite pressure pipe. The external expanding seamless hot-melt connection method is characterized in that the steel-plastic composite pressure pipe and a plastic pipe are included, wherein the steel-plastic composite pressure pipe comprises a steel pipe layer, an inner plastic pipe layer and an outer plastic pipe layer; the plastic pipe comprises an inner ring part, an outer ring part and an annular socket-and-spigot cavity; an air bag placed in the plastic pipe communicates with an air pipe; the air pipe is externally connected with an air filling device; the air bag is cylindrical after being fully filled with air and clung to the inner ring part; the steel-plastic composite pressure pipe is inserted into the annular socket-and-spigot cavity; an electromagnetic melting tool is electrified to heat the steel pipe layer in the annular socket-and-spigot cavity; the inner and outer plastic pipe layers are molten after being heated; the air bag is constantly extruded to enable the heated inner ring part to deform; the gap between the inner ring part and the inner plastic pipe layer is fully filled with the inner ring part; the electromagnetic melting tool is powered off and removed; and after the steel-plastic composite pressure pipe and the plastic pipe are cooled and solidified, the air bag is deflated, and the air bag and the air pipe are separated. With the adoption of the external expanding seamless hot-melt connection method for the large-diameter steel-plastic composite pressure pipe, the fusion seam generated due to the objective existing out-of-round defect of the large-diameter steel-plastic composite pressure pipe is fully filled with the inner ring part, the fusion seam between the inner plastic pipe layer and the inner ring part is eliminated, and the limitation on the connecting diameter is low.

Description

【Technical field】 [0001] The invention relates to a large-diameter steel-plastic composite pressure pipe expansion-type seamless hot-melt connection method, which belongs to the technical field of pipe welding. 【Background technique】 [0002] In the construction of pipeline engineering, it is difficult for the steel-plastic composite pressure pipe to form a tight seal with the plastic pipe fittings. There is inevitably a welding gap between the steel-plastic composite pressure pipe and the inner ring of the plastic pipe, resulting in leakage. Plastic composite pressure pipes objectively have out-of-round defects (such as caused by manufacturing, transportation, etc.), and the welding gap will become uncontrollable. For large-diameter welding of supporting plastic pipe fittings and steel-plastic composite pressure pipes with a diameter greater than 110mm, Welding gaps are bound to be more difficult to control. [0003] How to promote the reliable, seamless and tightly sealed...

AI Technical Summary

Problems solved by technology

[0005] 2. Restricted by the connection diameter of metal-plastic composite pipes and pure plastic pipe fittings, it is difficult to adapt to the welding of metal-plastic composite pipes and pure plastic pipe fittings with a diameter of more than 110mm. Seamless Welding of Caliber Tubes

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