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Welding stress and deformation control method for local post-weld heat treatment of super large pressure vessels

A pressure vessel and post-heat treatment technology, applied in the direction of heat treatment process control, heat treatment furnace, heat treatment equipment, etc., can solve the problems of increased deformation, uncoordinated deformation, cracking, etc., and achieve the effect of reducing stress and reducing radial deformation.

Active Publication Date: 2020-06-02
CHINA UNIV OF PETROLEUM (EAST CHINA) +1
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, for large vessels, the larger the area of ​​local heat treatment, the greater the deformation due to the degradation of material properties at high temperatures; in practice, the insert and the cylinder are welded with different thicknesses
Existing engineering cases show that when such welds are subjected to local heat treatment, due to excessive radial deformation, large angular deformations occur at the welds connecting thick plates and thin plates, resulting in serious deformation inconsistencies, resulting in occurrence of cracking

Method used

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  • Welding stress and deformation control method for local post-weld heat treatment of super large pressure vessels
  • Welding stress and deformation control method for local post-weld heat treatment of super large pressure vessels
  • Welding stress and deformation control method for local post-weld heat treatment of super large pressure vessels

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Effect test

Embodiment 1

[0072] Such as Figure 2-3 , super large pressure vessel cylinder thickness 50mm, diameter 40m, insert plate thickness 120mm, height about 6m, width about 4m. The size of the reinforced structure is 1200mm in length, 40mm in thickness, 300mm in height, and 800mm in spacing. The numerical simulation method is used to simulate the local post-weld segmental heat treatment of the large insert plate and its reinforcement scheme respectively, and the stress and deformation distribution of the lower path P1 of the insert plate are output as follows: image 3 shown. image 3 In (a), the ordinate represents the axial stress value of the lower path P1 of the insert plate, and the abscissa represents 125 mm from both sides of the weld. image 3 In (b), the ordinate represents the radial deformation value of the lower path P1 of the insert plate, and the abscissa represents 600 mm from both sides of the weld. Depend on image 3 (a) It can be seen that the local post-weld heat treatmen...

Embodiment 2

[0074] Such as Figure 4-5 , super large pressure vessel cylinder thickness 50mm, diameter 40m, insert plate thickness 120mm, diameter about 4.2m. The size of the reinforced structure is 1000mm in length, 40mm in thickness, 300mm in height, and 800mm in spacing. The numerical simulation method is used to simulate and calculate the local post-weld heat treatment and its reinforcement scheme, and output the stress and deformation distribution of the lower path P1 of the insert plate as follows: Figure 5 shown. Figure 5 In (a), the ordinate represents the axial stress value of the lower path P1 of the insert plate, and the abscissa represents 125 mm from both sides of the weld. Figure 5 In (b), the ordinate indicates the radial deformation value of the lower path P1 of the insert plate, and the abscissa indicates the distance from both sides of the weld 500mm. Depend on Figure 5 (a) It can be seen that the local post-weld heat treatment reinforcement scheme of the present...

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Abstract

A control method for welding stress and distortion in local post weld heat treatment of an ultra-large pressure vessel, comprising the followings steps: selecting an appropriate piecewise symmetric heat treatment scheme according to different insert types; arranging reinforcement structures perpendicularly to a welding seam in the tangential direction of the welding seam, and determining the material, number and size of the specific reinforcement structures; and checking, on the basis of the steps above and by means of finite element modeling analysis, key positions of the reinforcement structures after the stress and the distortion levels meet engineering requirements, and determining the actual reinforcement structure welding mode. By means of finite element modeling optimization, it is verified that on the basis of the use of piecewise symmetric heat treatment, implementing the reinforcement structures can effectively control the welding stress and distortion in local post weld heat treatment of the ultra-large pressure vessel, and the basis for selecting the number and size of the reinforcement structures is proposed.

Description

technical field [0001] The invention relates to the field of welding technology, in particular to a welding stress and deformation control method for local post-welding heat treatment of super-large pressure vessels. Background technique [0002] The super-large and thick-walled pressure vessel is made of tailor-welded plates, and the thick plate welds are subjected to post-weld heat treatment according to the specifications. For small containers, the overall heat treatment in the furnace can be carried out or the heat treatment can be carried out by igniting the inside of the container through a manhole. This is clearly not possible for larger container sizes, the standard specification no longer applies, and there is currently no standard exempt heat treatment. Local heat treatment can be carried out according to the actual situation, which is a feasible solution. However, for large vessels, the larger the area of ​​local heat treatment, the greater the deformation due t...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C21D9/50C21D11/00
CPCC21D9/50C21D11/00
Inventor 蒋文春金强罗云万娱涂善东王成才晏桂珍杨中伟
Owner CHINA UNIV OF PETROLEUM (EAST CHINA)