A local post-weld heat treatment method for butt joints of three-way branch pipes

Abstract

The invention relates to a local post-weld heat treatment method for butt joints of three-way branch pipes ， It uses the main heating device and the auxiliary heating device to heat the butt joint of the three-way branch pipe at the same time. The heating elements of the main heating device are arranged symmetrically at both ends of the weld with equal power and equal width, and the width of each end is equal to the height of the branch pipe. The thermocouple is arranged on the position of the welding seam opposite to the apex of the tee abdomen, and the heat treatment curve is set according to the given post-weld heat treatment process parameters; the heating element of the auxiliary heating device is arranged on the main pipe with the branch pipe as the center, and the temperature control thermoelectric The pair is arranged on the apex of the tee shoulder, and the real-time temperature control temperature is the real-time temperature at the position at the end of the pipe opposite to the apex of the tee abdomen when the main heating device is heating ± 10 ℃。 The method of the invention effectively avoids the deviation of the highest temperature point in the heating area from the weld seam, reduces the circumferential temperature difference of the weld seam, overcomes the adverse effects of the traditional post-weld heat treatment method, and meets the technical requirements for post-weld heat treatment of joints 。

Description

technical field [0001] The invention relates to a local post-weld heat treatment method for a tee branch butt joint, which is particularly suitable for the local post-weld heat treatment of a T-shaped tee branch butt joint. Background technique [0002] Post-weld heat treatment is a kind of heat treatment to eliminate the residual stress of welded joints and improve the structure and performance of welded joints. The general process is: install thermocouple → arrange heating device → set heat treatment parameters → wrap insulation cotton → perform heat treatment . [0003] The tee is an important connecting part of the piping system. When post-weld heat treatment is required after welding with external pipes at the service site, usually only partial post-weld heat treatment can be performed. One end of the butt joint is connected to the external pipe, and the other end is connected to the tee, so there is a significant difference in the heat dissipation conditions at both e...

AI Technical Summary

Problems solved by technology

This empirical method often makes the highest temperature point not exactly located on the weld, and it is difficult to avoid the circumferential temperature difference

The excursion of the maximum temperature and the existence of the circumferential temperature difference deteriorate the temperature field of the post-weld heat treatment of the joint, increase the residual stress of the joint after heat treatment, and have an adverse effect on the service performance and life of the joint; when the maximum temperature of the deviation exceeds the material After the phase transition point, the material recrystallizes, causing serious damage to the performance of the joint, and even directly leading to the scrapping of the joint

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