... s requiremntsInternatioanal StandardISO 9001-2000StandardsASTMA53,BS1387-1985,GB/T3091-2001,GB/T13793-92, GB/T6728-2002MaterialsQ195,Q215,Q235,Q345Product ... :86-10-59574179-206 Fax : 86-10-59574107 black square pipeSize Wall thickness (W.T.)13mm*13mm-400mm* ... s requiremntsInternatioanal StandardISO 9001-2000StandardsASTMA53,BS1387-1985,GB/T3091-2001,GB/T13793-92, GB/T6728-2002MaterialsQ195,Q215,Q235, ...