double standard seam 中文意思是什麼
double standard seam
解釋
加力縫-
Standard specification for steel line pipe, black, plain end, longitudinal and helical seam, double submerged - arc welded
雙埋弧焊縱向和螺旋焊縫平頭無鍍層鋼制總管的標準規范
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