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Local heat treatment residual heat stress control method of spherical vessel

A technology of local heat treatment and residual thermal stress, which is applied in the field of heat treatment, can solve problems such as the inability to guarantee the effect of heat treatment, and achieve the effects of avoiding stress corrosion cracking and brittle fracture, safe and convenient operation, and increasing safety and reliability

Active Publication Date: 2006-09-20
TIANJIN SPECIAL EQUIP INSPECTION INST
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  • Application Information

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Problems solved by technology

The local heat treatment effect evaluation in the project needs tens of thousands of yuan (usually more than 30,000 yuan), and most users are unable to pay, so that the selection of process parameters is in a state of blindness, and the effect of heat treatment cannot be guaranteed

Method used

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  • Local heat treatment residual heat stress control method of spherical vessel
  • Local heat treatment residual heat stress control method of spherical vessel
  • Local heat treatment residual heat stress control method of spherical vessel

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Embodiment Construction

[0014] The present invention will be further described in detail below in conjunction with specific embodiments: A method for controlling the residual thermal stress of a spherical container in local heat treatment, firstly calculate the area of ​​the circular heating area according to the volume of the spherical container, the wall thickness and the area of ​​the treated area required for local heat treatment. arc length radius, place the selected heating appliance on the area to be treated for heating. Can be heated on one side or on both sides. When the inner single-sided heating is used, the corresponding outer surface should be provided with an insulating layer; when the outer single-sided heating is used, the corresponding inner surface should be provided with an insulating layer. However, regardless of single-sided heating or double-sided heating, the surface of the heating appliance in contact with the air should be reliably insulated. The heating surface is circular ...

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Abstract

This invention discloses a method for controlling the residual thermal stress in spheric containers caused by local thermal treatment. The method comprises the steps of: (1) calculating the arc length or radius of the circular heating zone according to the volume, wall thickness and the area of the zone to be treated; (2) placing the heating device in the zone to be trated and heating; (3) performing single-sided or double-sided heating, and installing an insulating layer; (4) controlling the heating speed not higher than 150 deg.C / h until the predetermined constant temperature is reached; (5) keeping the temperature for a certain time; (6) cooling at a speed not high than 50% of the heating speed; and (7) removing the insulating layer. This invention can reduce the residual thermal stress in spheric containers caused by local thermal treatment by 60% to even 100%, thus can avoid such problems as stress corrosion cracking and brittle fracture, and can improve the operation safety of large scale equipment.

Description

technical field [0001] The invention relates to heat treatment technology, in particular to a method for controlling the residual thermal stress of a spherical container during local heat treatment. Background technique [0002] Spherical containers are widely used in petroleum, petrochemical, chemical and municipal industries, and belong to large-scale pressure-bearing special equipment. During use, dangerous defects such as cracks often appear in spherical containers, which need to be repaired by welding. Due to the inherent characteristics of the welding process, welding residual stress is inevitable, and because the wall thickness of the spherical tank is usually large and the binding force is strong, the residual stress caused by repair welding usually reaches the yield limit of the material, posing a potential threat to the safe operation of the equipment. Therefore, heat treatment is required to eliminate welding residual stress. In engineering, local heat treatment...

Claims

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Application Information

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IPC IPC(8): C21D9/00C21D9/50C21D11/00
CPCY02P10/20
Inventor 王泽军胡津康杨念慈萧艳彤牛卫飞刘宏臣陆金明
Owner TIANJIN SPECIAL EQUIP INSPECTION INST
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