Steel safety shell welding technology without post weld heat treatment

Abstract

The invention provides a steel safety shell welding technology without post weld heat treatment. The steel safety shell welding technology without post weld heat treatment comprises the following steps of preparation before welding and control of welding parameters: a workpiece is preheated with the preheating temperature being larger than or equal to 90 DEG C; welding steps: when manual arc welding is performed on the workpiece, the welding current is a direct current, the polarity is positive, the grade of diffusible hydrogen of a welding rod is a grade with H4 or above, the interpass temperature in the welding process is smaller than or equal to 200 DEG C, and the welding heat input is larger than or equal to 14kJ / cm, wherein the workpiece is an SA 738 Gr. B steel safety shell with thethickness being 60mm. The steel safety shell welding technology without post weld heat treatment is applied to welding of nuclear power station steel safety shell barrel girth welds, barrel longitudinal welds, insertion plates and barrel welds, lowers the construction difficulty brought by post weld heat treatment, reduces construction hidden dangers, saves the construction cost, accelerates the construction progress and ensures the construction quality.

Description

technical field [0001] The invention relates to a steel containment vessel exempting post-weld heat treatment welding process. [0002] d Background technique [0003] Since the steel containment plates are designed using the 2007 edition and the 2008 edition addendum to ASME code volume III NE subvolume. The maximum nominal wall thickness of the SA-738Gr.B plate exempted from post-weld heat treatment specified in the NE subvolume of Volume III of the 2007 edition of the ASME code is 44mm. According to this requirement, post-weld heat treatment is required for the splicing welds of the steel containment cylinder with a nominal wall thickness greater than 44mm. [0004] According to the provisions of NE-4624.3: When the container or item cannot be subjected to the overall post-weld heat treatment, local post-weld heat treatment can be performed. When performing localized post-weld heat treatment, a ring shall be heated along the vessel. However, since the diameter of the ...

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Problems solved by technology

However, since the diameter of the CAP1400 steel containment vessel is 43 meters, the electric power required for simultaneous post-weld heat treatment in one circle is 5000KW. The main problem brought about by this heat treatment method is that the on-site electric power cannot be solved. Secondly, the construction is very difficult, and the heat treatment temperature is difficult to control. , There is a great risk, and improper control will bring greater security risks

Post-weld heat treatment for such a large-diameter cylinder is encountered for the first time in the on-site installation of a nuclear power plant, and it is obviously impossible to perform post-weld heat treatment in accordance with ASME regulations.

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