Different steel pipe would have its special production method, so that they would have multifarious characters. Today, we would like to talk about black ERW steel pipe among welded steel pipe. 1)It is a kind of steel pipe made by hot-rolled coil through the molding machine; 2)Main production method would be high-frequency; 3)Compared with ordinary welding steel pipes production technology, black steel pipe has better technical on body melting, mechanical strength; 4)Black ERW steel pipe has features of smooth appearance, high precision, low cost welding seam height and so on.