Compound welding method for large-diameter compound steel pipe with pipe ends provided with corrosion resistant alloy through surfacing

Abstract

The invention discloses a compound welding method for a large-diameter compound steel pipe with pipe ends provided with corrosion resistant alloy through surfacing. The compound welding method is suitable for continuous corrosion preventing treatment for the inner wall of a weld of a joint of a large-diameter steel pipeline with the inner wall provided with a corrosion resistant layer. The compound welding method is characterized in that during pipeline welding construction of the compound steel pipe with the inner walls of the steel pipe ends provided with the corrosion resistant alloy through surfacing and with the inner wall coated with a corrosion resistant coating, argon-filling-free stainless steel or a nickel-based flux-cored wire and argon are adopted for double protection, and a positioned back welding layer is welded semi-automatically; certain carbon steel components are fused through large welding parameters in a semi-automatic welding mode by adopting argon-filling-free stainless steel or a nickel-based flux-cored wire and argon for double protection, and a transition weld layer with a certain ferritic structure is formed; metal of a filling weld layer and metal of the transition weld layer diffuse mutually through a low-carbon steel flux-cored self-shielded welding wire in a semi-automatic welding mode; and through a cosmetic weld layer with low-carbon steel welding materials, metallurgical fusion between a stainless steel or nickel-based alloy weld layer and a surfacing layer is achieved, metallurgical fusion between the low-carbon steel weld layer and the stainless steel or nickel-based alloy weld layer is achieved, the restricted zone of welding and fusing low-carbon steel welding materials on a stainless steel or nickel-based alloy material is broken, and pipeline welding construction quality and efficiency for the large-diameter surfacing compound steel pipe are improved.

Description

technical field [0001] The invention relates to the technical field of pipeline welding, in particular to a pipeline composite welding method for surfacing corrosion-resistant alloy composite steel pipes at pipe ends with large apertures. Background technique [0002] Most pipeline transport media contain corrosive substances such as sulfide and chloride, which are easy to corrode steel pipes and cause medium leakage. Usually, the inner and outer walls of steel pipes are treated with anti-corrosion treatment to improve their anti-corrosion performance and prolong the service life of the pipes. The inner wall of the steel pipe is generally coated with solvent-based or solvent-free anti-corrosion materials in the factory, and then welded to the construction site to form a pipeline; due to the high temperature of the pipeline welding, the anti-corrosion layer in the area near the weld is damaged. The "mouth" robot performs secondary anti-corrosion treatment on the inner wall o...

AI Technical Summary

Problems solved by technology

[0007] The purpose of the present invention is to provide a large-aperture pipe end surfacing welding corrosion-resistant alloy composite steel pipe composite welding method, which uses stainless steel or nickel-based alloy welding wire + argon protection to solve the problem of large-aperture pipe end surfacing corrosion-resistant alloy The problem of molten pool protection during butt welding of patched composite steel pipes; solves the metallurgical fusion problem of welding carbon steel welding consumables on stainless steel or nickel-based welding layers, which is a stainless steel or nickel-based alloy welding consumables + low carbon steel welding consumables The pipeline composite welding technology, the specific steps are as follows:

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