steel tube standards ASTM, API, DIN, EN, BS, JIS, UL, usage:structure, liquid transfering,sprinkler syetem.frame,fence tube steel tubeincluding ERW and Seamless, round and ... , casing pipe, sprinkler fire fighting system tube (with groove available), furniture tube, fence tubes and so onCERTIFICATE: ISO9001, UL, FM, CE, API steel tube