Metal welded pipe joint and assemble-welding method

Abstract

The invention discloses a tube welding joint. The tube welding joint comprises a tube piece body and a connecting tube. The tube welding joint is characterized in that a joint socket of the tube piece body is provided with a conicity section part; the connecting tube is inserted into the joint socket of the tube piece body to form socket lapping and butt welding and molding. The invention also discloses a method for welding the tube welding joint. The method is characterized in that the method sequentially comprises the following steps: 1) pretreatment and preconfiguration; 2) placing of an inner gas protective device; 3) interface in-place of the socket lapping tube piece; 4) temporary fixing; and 5) butt welding and molding. A socket lapping mode and a tube joint mounting structure realize a smooth welding joint of which weld joint is in butt welding and double-sided molding, radically remove the existence of crack between socket cylinder bodies and remove silt of the tube port at the same time to form the smooth tube welding joint without any crack and clearance. The mounting mode realizes accurate and rapid joint mounting mode and has convenient operation and simple and reliable mounting. The tube welding joint can be widely applied to socket mounting of water, gas, steam and equipment supply for building, industrial fluid, food and medicine fluid and other pipe assembly.

Description

technical field [0001] The invention relates to joints, in particular to a welded pipe joint and its welding method. Background technique [0002] Most of the thin-walled metal pipes that adopt argon arc welding, plasma welding, and carbon dioxide welding in the existing pipeline system adopt the socket lap welding method. When installing, the thin-walled metal pipe is used as the insertion pipe, inserted into the socket of the pipe fitting, and welded with the pipe at the end of the socket. Chinese patents CN2886275Y and CN2011Q3755Y respectively disclose solutions to the connection and welding of thin-walled stainless steel pipes. Their common shortcomings are corrosion and unhygienic problems, causing crevice corrosion, stress corrosion, and flame corrosion. The main reason is that there is a large gap between the inner wall of the socket and the outer wall of the socket, and the slits and lap welds at the transition of the socket and the end face of the socket will caus...

AI Technical Summary

Problems solved by technology

Chinese patents CN2886275Y and CN2011Q3755Y respectively disclose solutions for connecting and welding thin-walled stainless steel pipes. Their common deficiency is that corrosion and unhygienic problems occur, causing crevice corrosion, stress corrosion, and flame corrosion.

The main reason is that there is a large gap between the inner wall of the socket and the outer wall of the socket, and the slits and lap welds at the transition of the socket and the end face of the socket will cause the following problems: 1) The shielding gas cannot enter the gap, resulting in Fire color will affect the corrosion resistance of pipelines; 2) Crevice corrosion will occur, which will cause system damage; 3) Dirt and fungi are easy to store in the gaps, which will affect the sanitation of pipelines

In addition, the lap welding is cooled too fast, the molten pool crystallizes unevenly, the grains are coarse, and the welding stress is relatively large

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