Pre-joint-coating method for welded junction of steel pipe

Abstract

The invention discloses a pre-joint-coating method for a welded junction of a steel pipe. The pre-joint-coating method comprises the steps that a stainless steel short pipe is inserted into the steelpipe from the end of the welded junction, so that a first end and a second end of the stainless steel short pipe are located in the steel pipe; from the first end, in the direction away from the shortpipe, a welding gun rotates and performs bead weld to the inner wall of the steel pipe to a first end point to form a first welding layer; from the first end point to the second end, the first welding layer and the stainless steel short pipe are solidly dissolved by the welding gun in order to form a point potential gradual transition from low carbon alloy to stainless steel, and the contact surface of the first welding layer and the short pipe is formed into a slope-like transition; and from the second end to the end of the welded junction, the bead weld of the inner wall of the steel pipe is performed by the welding gun to form a second welding layer. The pre-joint-coating method for the welded junction of the steel pipe solves the technical problem in the prior art that the anticorrosion joint coating for the interior of the steel pipe is difficult, and achieves the technical effect of reducing the risk of safety and environmental protection caused by corrosion leakage of the pipeline.

Description

technical field [0001] The invention relates to the technical field of pipeline technology, in particular to a method for pre-filling welded joints of steel pipes. Background technique [0002] Steel pipeline welds are the weakest link in corrosion resistance. In all pipeline corrosion leakage accidents, pipeline weld corrosion accounts for more than 60%. In order to prolong the service life of pipelines, in the construction of internal anti-corrosion pipelines, it is necessary Carry out anti-corrosion treatment, this process is called "pipeline internal repair"; [0003] The inner joint of the pipeline is generally realized by the joint joint robot. It is necessary to clean the inner wall of the pipeline welding joint first, and then spray the liquid anti-corrosion coating to make the anti-corrosion layer in the pipeline continuous; Internal filling cannot be realized; [0004] For small-diameter pipes, the method of on-site paint extrusion is generally used for internal ...

AI Technical Summary

Problems solved by technology

[0006] The present invention solves the technical problem of high difficulty in the internal anti-corrosion repairing of steel pipes existing in the prior art by providing a method for pre-filling welded joints of steel pipes

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