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Method for guaranteeing uniformity of heat treatment of large-diameter thick-wall pipe weld

A thick-walled tube, uniform technology, applied in heat treatment furnaces, heat treatment equipment, heat treatment process control and other directions, can solve problems such as poor practicability and poor operability, and achieve the effect of strong real-time performance, easy operation, and improved performance of welded joints

Active Publication Date: 2018-11-23
SUZHOU NUCLEAR POWER RES INST +2
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In response to this, many researchers have done a lot of work, mainly focusing on two parts: 1. By controlling the heating width, heat preservation width, heating and cooling speed, temperature control temperature, and ambient temperature to adjust the distribution of the heat treatment temperature field, the regularity is obvious, Easy to implement; 2. Reduce the temperature difference between the inner and outer walls by controlling the draft on the inner wall of the pipeline and adjusting the heating device on the inner wall of the pipeline. The heating device on the inner wall is all attached to the inner wall of the pipeline to heat it, which has poor operability and poor practicability

Method used

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  • Method for guaranteeing uniformity of heat treatment of large-diameter thick-wall pipe weld
  • Method for guaranteeing uniformity of heat treatment of large-diameter thick-wall pipe weld
  • Method for guaranteeing uniformity of heat treatment of large-diameter thick-wall pipe weld

Examples

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Effect test

Embodiment 1

[0040] A steam drum cylinder of a pressure vessel is made of low alloy steel SA-299, with an inner diameter of Φ1778mm, an upper wall thickness of 196.1mm, a lower wall thickness of 163.9mm, and a total length of 28.91m including the heads on both sides. There are two girth welds on it There are excessive defects such as cracks and inclusions, and some defects show penetration of the inner and outer walls. After the welding repair is completed, the process requires local post-weld heat treatment for the two repaired girth welds. The heat treatment temperature is required to be 550 ° C. The speed does not exceed 50°C / h.

[0041] Adopt the method of the present invention to carry out partial post-weld heat treatment to two girth welds, concrete implementation steps are as follows:

[0042] (1) Selection of heating power

[0043] According to the post-weld heat treatment process requirements, the heating power calculation formula P=KWC(T a -T b ） / 3600t . in, P Power requ...

Embodiment 2

[0049] A steam drum cylinder of a pressure vessel is made of low-alloy steel SA-299, with an outer diameter of Φ2200mm, a wall thickness of 195mm, and a total length of 27.2m including the heads on both sides. The longitudinal weld between the 2nd and 3rd girth welds has excessive defects within 1.49m, and the defect position is 136-146mm away from the outer wall. The defects are eliminated from the inner wall, and the longitudinal weld is repaired after welding. Partial post-weld heat treatment, the constant temperature of heat treatment is required to be 550°C, and the heating and cooling rate should not exceed 50°C.

[0050] Adopt the method of the present invention to carry out partial post-weld heat treatment to two girth welds, concrete implementation steps are as follows:

[0051] (1) Selection of heating power

[0052] When the temperature rise rate of the post-weld heat treatment process is 50°C / h, the calculated power of the main heat source required for heating the...

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Abstract

The invention relates to a method for guaranteeing the uniformity of heat treatment of a large-diameter thick-wall pipe weld. The method comprises the following steps: heating the pipe cavity of a pipe located at a weld position when heating the outer wall of the pipe located at the weld position, and then heating the inner wall of the pipe. Through the heat treatment process for simultaneously heating the inner wall and the outer wall, the temperature difference between the inner wall and the outer wall of the large-diameter thick-wall pipe weld can be reduced; the purpose of eliminating thewelding residual stress through heat treatment and improving the welding joint performance can be fulfilled; the problem about the poor heat treatment of the inner wall of the pipe can be solved; thepurpose of the uniform heat treatment of the weld can be integrally fulfilled; and especially, the heat treatment effect on a thick-wall pipe weld can be more obvious. The method is obvious, simple and economical; and furthermore, the method is strong in real-time performance and easy to operate on site.

Description

technical field [0001] The invention relates to the technical field of welding heat treatment, and relates to a method for ensuring the uniformity of heat treatment of weld seams of large-diameter thick-walled pipes. Background technique [0002] In industrial boilers, due to the relatively low working pressure and temperature, generally only carbon steel is used, and sometimes some low alloy steel is also used. In power plant boilers, the working pressure and temperature are high. In addition to carbon steel and low alloy steel, some medium alloy steel and high alloy steel are also used. However, regardless of industrial boilers or power plant boilers, there are welding heat treatment requirements for steel weldments in installation, maintenance and factory preparation, such as the main steam pipes of power plant ultra-supercritical boilers, reheating hot section pipes, headers, etc. Wall components, high weld hardness and low toughness have become a major problem in the i...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21D9/50C21D9/08C21D11/00
CPCC21D9/08C21D9/50C21D11/00
Inventor 张建林赵建仓王淦刚鲁立陈忠兵杨佳
Owner SUZHOU NUCLEAR POWER RES INST
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