JIS G3444 STK400 pre-galvanized steel pipes JIS G3444 STK290,STK400,STK490,STK500,STK540 OD:1/2''- ... EN10217, DIN28180,DIN17175, DIN EN10305, DINEN 10025Certificate ISO9001-2008,EN10210,API,Raw material cert,Mill cert,Reap on site inspection report ... Welded (ERW )Electronic Fusion Welded (EFW)Double Submerged Arc Welded (DSAW)Surface Treatment1)Bared2)Black Painted (varnish coating)3)Galvanized4)With ...