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A kind of local post-weld heat treatment method of tee main pipe butt joint

A post-weld heat treatment and butt joint technology, which is applied in heat treatment furnaces, heat treatment equipment, furnaces, etc., can solve problems such as damage to joint performance, the highest temperature point cannot be located exactly on the weld seam, adverse effects on joint performance and life, etc.

Inactive Publication Date: 2016-06-08
SUZHOU NUCLEAR POWER RES INST +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This rule-of-thumb method often results in the highest temperature point not being exactly on the weld
The excursion of the maximum temperature and the existence of the circumferential temperature difference, the temperature field of the deteriorated post-weld heat treatment of the joint, increases the residual stress of the joint after heat treatment, and has 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

Method used

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  • A kind of local post-weld heat treatment method of tee main pipe butt joint
  • A kind of local post-weld heat treatment method of tee main pipe butt joint
  • A kind of local post-weld heat treatment method of tee main pipe butt joint

Examples

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Effect test

Embodiment 1

[0065] There is a 45° oblique Y tee on a pressure pipeline, the material is 12Cr2Mo1G, the main pipe specification is OD660×85.34 (mm), the branch pipe specification is OD457×64.30 (mm), the butt joint of the main pipe is 175mm from the step of the tee branch pipe, and it is connected to the main pipe The pipe material is P22, and the specification is OD650×80.0(mm). Branches and main pipes are welded to external piping. The welding process requires post-weld heat treatment for the welded joints of the main pipe. The heating width of the post-weld heat treatment is twice the wall thickness of the main pipe on both sides of the weld. The given post-weld heat treatment process parameters are: constant temperature 740 ° C, constant temperature time 4.0 h, the heating and cooling rate is 75°C / h.

[0066] Using the method of the present invention to carry out local post-weld heat treatment on the main pipe butt joint, the specific implementation steps are as follows:

[0067] (1)...

Embodiment 2

[0077] There is a T-shaped tee on the steam pipe of a power station, the material is P22, the specification of the main pipe is OD426×95.0 (mm), the specification of the branch pipe is OD406×90.0 (mm), the distance from the butt joint of the main pipe to the center of the branch pipe is 470mm, and the pipe connected to the main pipe The material is P22, and the specification is OD419×90.0(mm). Branches and main pipes are welded to external piping. The welding process requires post-weld heat treatment for the welded joints of the main pipe. The heating width of the post-weld heat treatment is twice the wall thickness of the main pipe on each side of the weld. The given post-weld heat treatment process parameters are: constant temperature 730 ° C, constant temperature time 4.0h, The heating and cooling rate is 60°C / h.

[0078] Using the method of the present invention to carry out local post-weld heat treatment on the main pipe butt joint, the specific implementation steps are ...

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Abstract

The invention relates to a local post-weld heat treatment method for a three-way main pipe butt joint, which uses a main heating device and an auxiliary heating device to heat simultaneously, and the heating elements of the main heating device are symmetrically arranged at both ends of the weld with equal power and equal width. The temperature control thermocouple is arranged on the side of the weld seam opposite to the side where the branch pipe is located, 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 close to the main pipe end of the main heating device, and the temperature control thermoelectric The pair is arranged at the position opposite to the apex of the tee shoulder on the main pipe at the end of the main heating device, real-time temperature control ±10°C. The method of the invention effectively avoids that the highest temperature point in the heating area deviates from the weld seam, reduces the circumferential temperature difference of the weld seam, and meets the technical requirements of post-weld heat treatment of the joint.

Description

technical field [0001] The invention relates to a local post-weld heat treatment method for a three-way main pipe butt joint, which is particularly suitable for the local post-weld heat treatment of a three-way main pipe butt joint whose branch pipes have been connected with external pipelines. 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 ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C21D9/50
Inventor 陈忠兵孙志强吕一仕
Owner SUZHOU NUCLEAR POWER RES INST