An automatic wire-filling welding process for electric heating elements of voltage stabilizers in nuclear power plants

Abstract

The invention belongs to the technical field of on-site replacement of electric heating elements of voltage stabilizers in nuclear power plants or equipment manufacturing and installation, and specifically relates to a complete process for on-site replacement of electric heating elements in nuclear power plant voltage stabilizers. The purpose is to reduce welding heat input and eliminate the risk of thermal cracks; Eliminate the risk of incomplete penetration of the weld or incomplete fusion at the root of the weld, and ensure that the inner and outer surfaces of the weld are well formed; replace the special ferrite filler ring with standard welding wire material as the welding material, and get rid of the import dependence of foreign materials. Cost reduction; automatic wire filling pulse tungsten electrode automatic welding process, and the supporting auxiliary process to realize the welding process, realize the on-site replacement of high-quality electric heating elements. The present invention has successfully realized the on-site replacement of a total of 14 electric heating elements in Fangjiashan 1 and 2# machines and Qin 2 Factory 1# machine in 4 times. All the replacements have achieved "one operation, one pass", and the process is reliable. has been successfully verified.

Description

technical field [0001] The invention belongs to the technical field of on-site replacement or equipment manufacturing and installation of an electric heating element of a voltage stabilizer in a nuclear power plant, and in particular relates to an automatic wire-filling welding process for an electric heating element of a voltage stabilizer in a nuclear power plant. Background technique [0002] The voltage stabilizer is an important device for the pressure boundary of the primary circuit of the nuclear power plant, and it mainly plays the role of stabilizing the pressure of the primary circuit. The electric heating element is the main functional element of the voltage stabilizer. The electric heating element is inserted into the inside of the voltage stabilizer from the penetrating part of the bottom head of the voltage stabilizer, and passes through the sleeve of the electric heating element. outer diameter It runs through the bottom head of the voltage stabilizer, and ...

AI Technical Summary

Problems solved by technology

This one-time self-fluxing welding process is relatively simple, but requires a large penetration depth. In order to ensure full penetration of the weld root, the welding process requires a large heat input, and the heat dissipation conditions of the connecting parts are poor, and thermal cracks are prone to occur.

In order to reduce the tendency of weld thermal cracking, the ferritic stainless steel filling ring is used as the filling material. This material is different from the base material, the impact toughness is lower than the base material, and the industrial consumption is small, so it needs to be smelted separately. The actual use mainly depends on imports. expensive

In addition, this structure has very high requirements for the centering of the weld bevel or welding arc, and a little carelessness may cause welding defects such as incomplete penetration or poor fusion on one side, and the formation of the root of the weld and the surface of the weld is not easy Taking into account, to a certain extent, affects the quality of the weld

Since the weld is a primary circuit pressure boundary weld, if the weld has welding defects such as unilateral infusion, incomplete penetration, or thermal cracks, it needs to be replaced again, causing huge losses

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