JIS G3444 STK540 pre-galvanized steel pipes JIS G3444 STK290,STK400,STK490,STK500,STK540 OD:1/2-10"W.T.:0.5-16MM LTH1-12M JIS G3444 STK540 pre-galvanized steel pipesO.DO.D toleranceW.TThickness Tolerance21-323mm±0.5mm1.5-16MM±1%Length 1-12M , according to customers' requirementsCertificate ISO9001-2008,EN10210,API,Raw material cert,Mill cert,Reap on site inspection report,SGS,BVStandardJIS ...