Method for butt welding end parts of two double-metal composite pipes respectively with adapter ring on the end part

Abstract

The invention relates to a method for butt welding end parts of two double-metal composite pipes respectively with an adapter ring on the end part. The method comprises the steps of preprocessing the end of a liner pipe, surfacing the inner wall of the adapter ring and the outer end of the liner pipe, machining a groove, grouping, spot welding, filling and cosmetic welding. Compared with the existing double-metal composite pipe welding method, the technical difficulty for annularly welding the thin-wall stainless steel liner pipe and the double-metal composite pipe of a medium-low-density carbon-steel base pipe layer can be solved, and the weakness that the prior art is not suitable for welding the composite pipe with the thickness of the liner pipe being less than or equal to 1mm can be overcome; the complicated welding of the double-metal composite pipe is transformed to the welding of the pure stainless steel; and by adopting the full-stainless-steel hand-operated electric arc welding for a circumferential weld, the welding efficiency can be effectively improved, the welding cost can be reduced, and the weaknesses of the argon arc welding that the process is complicated and the requirement on the natural environment is not strict can be overcome. The method has the advantages of simple welding tool, high welding efficiency, low welding cost and the like and can be used for welding the ends of two double-metal composite pipes with the wall thickness of the liner pipe being less than 1mm.

Description

technical field [0001] The invention belongs to the technical field of bimetallic composite pipes, and in particular relates to the butt welding connection at the ends of two bimetallic composite pipes. Background technique [0002] Bimetal composite pipe can effectively solve the corrosion problem of pipelines in oil and gas transportation, oil refining, chemical industry and other industrial sectors, but the welding of bimetal composite pipe is different from the welding of ordinary pure metal pipes, and it has some characteristics of its own. At present, the widely used welding technology is the welding of bimetallic composite pipe without adapter ring. The welding method is argon arc welding for backing, electric welding for transition layer and base pipe layer. There are mainly two types: [0003] One is to weld the inner lining first, and then weld the transition layer and the base pipe. The welding consumables are all stainless steel welding consumables, stainless ste...

AI Technical Summary

Problems solved by technology

The problem that this technology is easy to produce is: because the mechanically bonded base lining gap is not sealed and welded, the water, air or other debris in the gap will affect the quality of the transition layer weld, resulting in pores, inclusions, and even crack defects; Welding is a special process, and when the lining is very thin and the lining weld is also thin, the molten base pipe Fe and C will inevitably penetrate into the lining weld, and even penetrate into the surface of the lining weld , affecting the corrosion resistance of the lining

Because the base pipe and the liner pipe are sealed and welded in advance, this technology can effectively avoid the adverse effect of the gap between the base pipe and the liner pipe on the girth weld. , it will be easy to weld through the lining during seal welding, and the carbon steel melt will penetrate into the stainless steel lining, which will affect the corrosion resistance of stainless steel, and the quality of seal welding cannot be guaranteed

[0005] Both of the above two welding methods involve the welding of dissimilar steels. During field construction, the field environment requires operators to master a high level of welding process, and it is easy to cause hardened martensite in transition welding due to wrong selection of welding materials and process specification problems. organization, or even weld cracks, it is difficult to guarantee the first pass rate of the weld; the above two welding methods both use argon arc welding root welding, and the tube needs to be filled with argon gas protection, the process is complicated, the efficiency is low, and the cost is high. And it is impossible to weld the dead seam of the pipe

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