A Construction Technology for Preventing Welding Cracks of Water-cooled Wall Tubes

Abstract

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. Adopting the construction technology for preventing cracks in the welded joints of water-cooled wall pipes provided by the invention can overcome the poor welding performance of T23 materials and the problems of high sensitivity to cracks, and eliminate the restraint stress existing in the water-cooled wall structure itself. At the same time, the welding technology of the invention can be installed on site During construction, the welding preheating and heat treatment are in place to reduce the welding stress, so that the hardness of the T23 weld is reduced, the weak link at the weld fusion line is eliminated, and cracks are not easy to occur. Variable stress, due to the improvement of the construction technology during the load change of the unit, there will be no large stress to crack the pipe, and it has broad application prospects.

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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