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大型球罐压力容器的切片球壳板都采用现场焊接成整体的安装工艺。球壳板厚度通常都在30mm以上,为避免焊后根部和内外表面存在裂纹、未熔合、未焊透、夹渣等缺陷而造成质量隐患,所以在焊接过程中必须对焊缝进行多次磁粉检测,包括焊接前的球壳板坡口检测、焊接过程中焊缝的坡口清根检测、焊后热处理前的焊缝及热影响区检测和水压后的焊缝和热影响区检测。而其中清根坡口磁粉检测则尤为重要。检测结果表明,在球罐赤道带以上焊缝容易产生应力裂纹、未熔合等缺陷,而清根坡口磁粉检测可以有效检测出根部的表面开口和近表面缺陷。
Large spherical tank pressure vessel sliced spherical shell panels are welded into the overall installation process. Spherical shell plate thickness usually 30mm above, in order to avoid post-weld root and inner and outer surface cracks, unfused, incomplete penetration, slag and other defects caused by quality problems, so the welding process must be repeated several times the magnetic powder Testing, including the testing of ball shell beveling before welding, the root cleaning of bevel in welding process, the testing of weld and heat affected zone before welding heat treatment and the testing of weld and HAZ after water pressure. Which Qinggu groove magnetic particle testing is particularly important. The test results show that the welds above the equatorial zone of the tank tend to cause defects such as stress cracks and unmelted welds, while the root clearance magnetic particle inspection can effectively detect the root surface openings and near surface defects.