Local heat treatment method after repair welding of inner wall of large quenched and tempered steel pressure vessel

Abstract

The invention discloses a local heat treatment method after repair welding of the inner wall of a large-scale quenched and tempered steel pressure vessel, which comprises the following steps: (1) determining the relevant size parameters of the repair welding area of ​​the quenched and tempered steel vessel; (2) determining the heating mode of the local heat treatment; (3) ) Determine the heating and cooling times of local heat treatment; (4) Determine the heating range of local heat treatment; (5) Determine the heat preservation range of local heat treatment; (6) Determine the heating process of local heat treatment: including heat treatment temperature and heat preservation time; (7) Arrange temperature measurement and temperature control thermocouple; (8) heat treatment is implemented, and the heat treatment temperature curve is recorded. The invention provides a local heat treatment method after repair welding of the inner wall of a large-scale quenched and tempered steel pressure vessel, which provides strict standard operation for the post-weld heat treatment and can effectively reduce the residual stress in the repair welding area.

Description

technical field [0001] The invention relates to the technical field of post-weld heat treatment of pressure vessels, in particular to a method for local heat treatment after repair welding of the inner wall of a large-scale quenched and tempered steel pressure vessel. Background technique [0002] In the process of manufacturing, installation and service of pressure vessels, various defects such as cracks, corrosion and wear will inevitably occur. If they are not dealt with in time, they will pose a great threat to the safe operation of the equipment. In order to prolong the service life of the pressure vessel and reduce the production cost, it is usually necessary to partially repair the pressure vessel by means of repair welding to restore its structural integrity. Residual stress, the existence of residual stress has a great impact on the later service life of repair welding equipment, especially easy to cause stress corrosion failure. Partial heat treatment after repair...

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Problems solved by technology

[0002] Cracks, corrosion, wear and other defects will inevitably occur in the process of pressure vessel manufacturing, installation and service. If not dealt with in time, it will pose a great threat to the safe operation of the equipment

In order to prolong the service life of the pressure vessel and reduce the production cost, it is usually necessary to partially repair the pressure vessel by means of repair welding to restore its structural integrity. Residual stress, the existence of residual stress has a great impact on the later service life of repair welding equipment, especially it is easy to cause stress corrosion failure

Local heat treatment after repair welding is an effective means to eliminate residual stress after repair welding, but the current domestic and foreign heat treatment standards have not made detailed regulations on the local heat treatment process after repair welding, such as heating method, heating range, heat preservation range, etc. These parameters It is the key to affect the stress relief effect of repair welding heat treatment

If the key process is not properly selected, an improper temperature gradient will be generated, new thermal stress and residual deformation will be introduced, and the heat treatment effect will be affected

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