... / LSAW / ERW / EFW WELDED STEEL PIPES;GOST 10704-91,GOST 10705-80 LONGITUDINALLY WELDING STEEL TUBES, GOST 20295-85 ELECTRICALLY WELDED ... SAWH / SSAW / SAW / SPIRAL WELDED STEEL PIPES;GOST 8696-74 ELECTRICALLY WELDED SPIRAL SEAM STEEL PIPES WITH 3PE,3PP,EPOXY,FBE,CEMENT ANTICORROSION ... etc. 3.HOT ROLLED SEAMLESS STEEL PIPES;GOST 8731-74,GOST 8732-78 SEAMLESS STEEL PIPES WITH 3PE,3PP,EPOXY,PITCH,ZINCRICH ...