Automatic Welding Method for Steel Containment Vessel of Nuclear Power Plant

Abstract

The invention relates to an automatic welding method of a nuclear plant steel safety shell and belongs to the technical field of nuclear plant building. The method adopts the match between a solid core welding wire and the active gas-shielded arc welding of a consumable electrode with specific process parameters, weaving welding is adopted for vertical welding seam,s and linear welding is adopted for horizontal annular seams. According to the method, internal and appearance qualities of the welding seams of the nuclear plant steel safety shell are improved, the safety is ensured, the efficiency for welding a thick plate of the steel safety shell is greatly improved, and the welding work period is obviously shortened.

Description

technical field [0001] The invention relates to a welding method, in particular to an automatic welding method for a steel containment vessel of a nuclear power plant, belonging to the technical field of nuclear power plant construction. Background technique [0002] As an important part of the passive system, the steel containment vessel (CV) of nuclear power plants can effectively prevent the internal pressure of the containment from exceeding the design value and prevent the leakage of radioactive materials under accident conditions. It is one of the important equipment to ensure the safe operation of nuclear power plants. The steel containment vessel of AP1000 third-generation nuclear power plant is a hermetic steel container, including three parts: bottom head, cylinder body and top head. It is about 3400m, and the groove section is large. Compared with CPR1000, EPR and other reactor-type nuclear power plants, the welding workload has increased by at least 8 times. [...

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Problems solved by technology

[0005] 1. The current, voltage, welding speed and other energy parameters of the SMAW process fluctuate greatly, and the probability of defects such as incomplete fusion, slag inclusions, and pores is relatively high, and at the same time, it is easy to cause local welding deformation to exceed the standard, and the stability and consistency of welding quality are relatively low. Difference

[0006] 2. The use of SMAW process requires frequent replacement of welding rods, regular interruption of the welding process, and heavy slag cleaning and grinding workload, greatly reducing welding efficiency, and it is difficult to guarantee the welding schedule

[0007] 3. The flame baking method is cyclical localized centralized heating. Under the objective condition of large heat dissipation area, the heat treatment of the weld seam using this method cannot achieve uniform distribution and constant heat treatment temperature in the length of the weld seam and the thickness direction, and the heat treatment quality can be improved. There is no guarantee, and it takes a long time to bake to the specified temperature, and consumes a lot of combustible gas

[0008] 4. The simple supporting electric heating method is to repeatedly support and fix the heating block on the weld seam and lay insulation cotton on the heating block. There is a greater risk in quality and low construction efficiency

Although the 201110351452.0, 201210368249.9, 201310304367.8, and 201310162438.5 applied by the applicant have improved the welding in the construction of nuclear power plants from different angles, they cannot be directly used to solve the above-mentioned problems of CV welding

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