During the periodic inspection of a refinery crude oil tank,a lot of cracks are found on the internal shell-to-bottom welds and the margin plate base metal near the welds.According to situations of the crack distribution and shape that achieved by further testing and fault removing,and combined with the stress and medium condition of the area,the reasons of crack formation are analyzed,and it is confirmed as stress corrosion cracks.Using relevant standards such as NACE SP 0296 and NACE SP 0472 for references,a series of repairing measures are specifically worked out,namely pre-welding hydrogen elimination should be done before crack removing,and the multi-layer welding and temper bead should be taken.After repairing,the surface test and hardness test are conducted in welding-repaired places,and the water filling test is conducted in the storage tank.At present,the crude oil storage tank has successfully come into use after repairing.%某炼厂原油储罐定期检验时在内大角焊缝及其附近边缘板母材上发现多处裂纹.根据进一步检测、消缺处理所掌握的裂纹分布区域及形态等情况,结合该区域受力和介质情况进行裂纹成因分析,确认为应力腐蚀裂纹.借鉴NACE SP 0296、NACE SP 0472等相应标准,有针对性地制订了先焊前消氢处理,再清除裂纹,然后采用多层焊和回火焊道的系列修复措施.修复后对焊接修补处进行表面检测和硬度检测,并对储罐进行充水试验.经修复,该原油储罐现已顺利投用.
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