球罐球壳板组对焊缝清根坡口的磁粉检测

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。

MAGNETIC PARTICLE TESTING IN GROUP CLEAN-GROOVE WELDS OF SPHERICAL TANK’S SHELL PLATE

Slice large spherical pressure vessel shell plates are welded on site using installation process.Shell thickness is usually 30 mm or more.To avoid cracks,incomplete fusion,incomplete penetration,slag and other defects caused by quality problems,so the welds must be inspected by repeated magnetic particle testing,including the groove detection of shell plate before welding,and the weld groove clean-test in the welding process,and the weld inspection before the heat treatment after welding,and heat-affected detection,and water pressure testing,and the detection of heat-affected zone,of which the clean-groove magnetic particle testing is particularly important.Test results show that stress cracks etc are easily produced in the weld at the sphere over the equatorial belt,and clean-groove magnetic detection can effectively detect the defects on the surface of the roots of the opening and near surfac.