1 肉眼で本物と偽物の溶融亜鉛メッキ継目無鋼管を識別する方法を教えるのに一分
Now there is a so-called hot-dip galvanized fluid pipe on the market, also called de-galvanized seamless pipe, in fact, it is a high-frequency welded pipe after treatment, the original weld with special equipment or planing off or grinding off and then galvanized. Now the identification of this kind of pipe