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

Abstract

The invention discloses a local heat treatment method for the inner wall of a large quenched and tempered steel pressure vessel after repair welding. The local heat treatment method comprises the following steps: (1) determining relevant size parameters of a repair welding area of the quenched and tempered steel pressure vessel; (2) determining a local heat treatment heating mode; (3) determining local heat treatment heating and cooling times; (4) determining a local heat treatment heating range; (5) determining a local heat treatment heat preservation range; (6) determining a local heat treatment heating process including heat treatment heat preservation temperature and heat preservation time; (7) arranging a temperature measurement thermocouple and a temperature control thermocouple; and (8) performing heat treatment, and recording a heat treatment temperature curve. According to the local heat treatment method for the inner wall of the large quenched and tempered steel pressure vessel after repair welding, strict standard operation is provided for postweld heat treatment, and the residual stress of the repair welding area can be effectively reduced.

Description

technical field [0001] The invention relates to the technical field of post-weld heat treatment of pressure vessels, in particular to a local heat treatment method after repair welding of the inner wall of a large quenched and tempered steel pressure vessel. Background technique [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 ...

AI Technical Summary

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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