Construction process for preventing welded junction of water-cooled wall tube from cracking

Abstract

The invention relates to a construction process for preventing a welded junction of a water-cooled wall tube from cracking, and belongs to the technical field of welding processes. By the adoption ofthe construction process for preventing the welded junction of the water-cooled wall tube from cracking, the problems that a T23 material is poor in welding performance and high in crack sensitivity can be solved, constraint stress existing in a water-cooled wall structure is eliminated, meanwhile, welding preheating and heat treatment are in place during field installation and construction, welding stress is reduced, the T23 weld joint hardness is reduced, the weak link of the weld joint fusion line part is eliminated, cracks are not likely to be generated, even if the water-cooled wall is poor in operation condition and has large alternating stress, due to the perfection of the construction process in the unit load changing process, large stress cannot be generated to crack a tube, and wide application prospects are achieved.

Description

technical field [0001] The invention relates to a construction technique for preventing cracks at the welding joint of a water-cooled wall tube, and belongs to the technical field of welding techniques. Background technique [0002] Taking Jianbi Power Plant of National Energy Group as an example (hereinafter referred to as Jianbi Power Plant), during the maintenance of the #13 furnace in the seventh phase in recent years, the factory took a large-scale photograph of the 73-meter T23 water-cooled wall pipe weld, and the results showed that , it can be seen that the defect rate of suspected cracks has reached 2.96%, and these weld joints suspected of cracks, after being heated and expanded in the hot state, even if one leaks, it may cause non-stop accidents of the unit and seriously affect the safety of the unit Completion of production and non-stop targets. [0003] The commonly used method at present: Since the motor of the reduction box of the air preheater is always in a...

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Problems solved by technology

[0002] Taking Jianbi Power Plant of National Energy Group as an example (hereinafter referred to as Jianbi Power Plant), during the maintenance of the #13 furnace in the seventh phase in recent years, the plant took a large-scale filming of the 73-meter T23 water-cooled wall tube weld, and the results showed that , it can be seen that the defect rate of suspected cracks has reached 2.96%, and these weld joints suspected of cracks, after being heated and expanded in the hot state, even if one leaks, it may cause non-stop accidents of the unit and seriously affect the safety of the unit Completion of production and non-stop indicators

[0003] The commonly used method at present: Since the motor of the reduction box of the air preheater is always in a rotating state during operation, if the motor of the reduction box fails, there is no way to deal with it, and the motor of the reduction box can only be repaired and replaced when the unit is out of operation.

[0004] However, this method has the following disadvantages: 1. T23 material has poor welding performance and high sensitivity to cracks

2. There is a large restraint stress in the water wall structure itself

3. Limited by the structure of the water-cooled wall, the welding preheating and heat treatment cannot be fully in place during on-site installation and construction, and there is a large welding stress

In the case of insufficient heat treatment, the hardness of the T23 weld is relatively high, and the weld fusion line is the weakest link, which is prone to cracks

4. The working condition of the water wall is poor, and there is a large alternating stress, which will cause a large stress to crack the pipe during the load change process of the unit

[0005] Due to the characteristics of the above-mentioned T23 steel at 73 meters, the existing means cannot detect cracks that are newly added in the hot state during the maintenance period, and these cracks may leak after being heated and expanded in the hot state, causing the unit to Non-stop accidents seriously affect the safe production of the unit and the completion of non-stop prevention indicators

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