A kind of sealing welding process of dissimilar steel grooved tube sheet and heat exchange tube

Abstract

The invention discloses a sealing welding process of a dissimilar steel grooved tube sheet and a heat exchange tube, including: A) preparation; B) expansion positioning: passing the heat exchange tube through the tube hole of the tube sheet and extending out of the end face of the tube sheet , Extend the expansion sleeve into the heat exchange tube, the front end of the expansion sleeve is provided with a tapered hole, and the outer circumference is provided with several convex arc expansion heads, and the outer ends of the arc expansion heads are axially located at the root of the tube plate groove and the inner side of the root. Between two millimeters; push the expansion mandrel in the expansion sleeve, so that the arc expansion head is supported outside, and the heat exchange tube is expanded and fixed in the tube hole; C) Cleaning; D) Welding: the single-position sealing welding head The positioning mandrel is inserted into the heat exchange tube to be welded and tightened. Under the protection of inert gas, the bottom layer welding is performed first, and 100% penetration inspection is performed after welding; then the surface layer welding is performed, and 100% penetration inspection + radiographic inspection is performed after welding ; E) heat treatment; the invention can solve the problem that dissimilar steel sealing welding is easy to produce cracks, and prevent incomplete penetration and fusion of the root, thereby improving the sealing welding quality.

Description

technical field [0001] The invention relates to a sealing welding process of a tube sheet and a heat exchange tube, in particular to a sealing welding process of dissimilar steel for a grooved tube sheet of a chemical container and a heat exchange tube. Background technique [0002] The chemical container has high requirements on the sealing welding quality of the tube sheet and the heat exchange tube. The sealing welding of some equipment requires radiographic inspection and macro testing, and requires complete penetration of the root without excessive defects. Conventional welding process is not easy to meet the requirements, mainly in the following aspects: [0003] 1. The material of the tube sheet and the heat exchange tube is different, especially the surface of the tube sheet has austenitic steel composite layer, when the heat exchange tube is low alloy steel, the chemical composition and performance of the two materials are very different, and the sealing welding of ...

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Problems solved by technology

[0005] 3. In order to ensure the tube penetration, there is a deviation between the outer diameter of the heat exchange tube and the tube hole. The positioning of the heat exchange tube before welding is usually fixed by spot welding. Due to welding shrinkage, the gap at the root of the groove will be uneven, and the spot welding position is prone to welding defects ; If no fixing measures are taken, the heat exchange tube will easily shake during welding, and serious unfused or cracks will easily occur during automatic welding

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