Method for welding circumferential weld between metal thin-wall clad layer and base layer of clad pipe

Abstract

The invention provides a method for welding circumferential weld between a metal thin-wall clad layer and a base layer of a clad pipe, which is used for welding circumferential weld of dual-metal clad steel pipes. The method is characterized by (A) groove processing: cleaning oil stains on the groove; (B) carrying out surfacing on the truncated edge, close to the clad layer, of the groove and coping the groove; (C) fitting up the groove of the dual-metal clad pipe; (D) root backing weld: adopting the gas tungsten arc welding method and carrying out welding along the groove of the dual-metal clad pipe under the state of argon-filled protection inside the pipe; (E) carrying out second layer welding on the root backing weld and welding the welding base layer of the dual-metal clad pipe; and (F) filled welding and cosmetic welding: wherein the welding materials are stainless steel electrodes. The method has the following effects: adopting 309 or 309Mo welding materials, thus ensuring the strength and good toughness of the weld; eliminating the gaps which probably exist between the clad layer and the base layer at the end of the groove; and increasing the effective thickness of the stainless steel layer at the groove root so that the quality of the welding joints are insensitive to misalignment, thus ensuring the corrosion resistance.

Description

technical field [0001] The invention belongs to the technical field of metal material welding, and relates to a welding technology for the girth weld of a double-metal clad steel pipe, in particular to a girth weld welding technology for a metal thin-walled clad pipe and a bimetal clad pipe whose base layer is carbon steel. Background technique [0002] The bimetal composite pipe with carbon steel as the base layer and stainless steel as the cladding layer effectively solves the corrosion problem of pipelines in oil and gas transportation, oil refining, chemical industry and other industrial sectors, and has more and more applications. It is very difficult to weld bimetallic composite pipes on site, and there are two main welding techniques at present. One of Chinese Patent Publication No. is the patent application of CN 1354061A. Firstly, weld the cladding layer on the inner wall, and then weld the transition layer and the base layer. The welding materials are all made of ...

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Problems solved by technology

[0004] The purpose of the present invention is to provide a thin-walled stainless steel clad layer and carbon steel base layer composite pipe girth weld welding method, to solve the technical problems of bimetal composite pipe girth weld welding stainless steel clad layer and carbon steel base layer, to overcome the existing welding The technology is not suitable for the welding of composite pipes with a cladding thickness of less than 2 mm; the use of stainless steel welding materials with the same composition as the cladding will cause a certain amount of martensitic hardening poor structure after the sealing weld is diluted by the base carbon steel, resulting in lack of crack

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