same length and space of tack weld
点焊间隔及焊道长度是否适当
Having been practiced for several years, a new butt method for spiral welded pipe, the two spots tack-weld butt was made out.
通过几年来的实践,摸索总结出了一种螺旋焊管对接新方法&两点点固对接法。
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