Partial heat treatment method for large pressure vessel with uneven thickness structure

By employing numerical simulation and optimized local heat treatment methods, the residual stress problem in welded joints of large pressure vessels was solved, enabling precise setting of heat treatment parameters and improving welding quality and efficiency.

CN115852126BActive Publication Date: 2026-05-01CHINA UNIV OF PETROLEUM (EAST CHINA)
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Patent Information

Application Number
CN202211443082.8
Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
Filing Date
2022-11-18
Publication Date
2026-05-01
Estimated Expiration
2042-11-18

AI Technical Summary

Technical Problem

Existing technologies cannot effectively eliminate residual stress during the welding of large pressure vessels, and traditional simulation methods fail to consider the influence of molten pool flow on the temperature field. This results in localized heat treatment process parameters for welded joints that cannot solve the technical problems of welded joints and large pressure vessels. Existing technologies cannot effectively guide the development of technical problems and cannot accurately determine localized heat treatment process parameters, leading to asymmetrical welded joint structures and affecting welding quality.

Method used

Numerical simulation was used to determine the width of the heating zone and process parameters for local heat treatment. The influence of molten pool flow on the temperature field was considered during the simulation. Local heat treatment was carried out by electromagnetic induction or resistance heating. Temperature and stress field simulation was performed by combining FEM and CFD methods to optimize the heat treatment process parameters.

Benefits of technology

It enables precise heat treatment of large pressure vessels with uneven thickness structures, reduces deformation and stress unevenness of welded joints, prevents cracking, and improves welding quality and efficiency.

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Abstract

This invention discloses a method for local heat treatment of unequal thickness structures in large pressure vessels, used for heat treatment of butt welded joints between the cylinder and reinforcing plate. The method includes the following steps: (1) determining the relevant dimensional parameters of the unequal thickness welded joint, including the inner diameter D of the cylinder, the cylinder wall thickness T, and the thickness t of the reinforcing plate. Then, the inner radius R of the cylinder is R = D / 2, the thickness ratio k = t / T, and t > T; (2) determining the local heat treatment heating method; (3) determining the optimal heat treatment process parameters, including the heating band width, holding temperature, holding time, heating rate, and cooling rate; (4) implementing the heat treatment and recording the heat treatment temperature curve. The method provided by this invention can provide optimal heating band width, holding temperature, holding time, heating rate, and cooling rate for local heat treatment of unequal thickness welded joints, effectively reducing inconsistent deformation and uneven stress distribution after local heat treatment of thick and thin plates, and preventing cracking of the unequal thickness welded joint.
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