Square Piping 1.steel tube,rule 20*20-400*400mm 2.square tube,thickness from0.4-9.0 3.steel pipe, length 4.8-9.0m we can provide all sizes square tube: 1.the rule 20*20-400*400mm square tube2.thickness from0.8-6.0mm square hollow section3.length from 4.8-9.0m4.standard:GB,ASTM,JIS,BS Shanghai Centrue is engaged supplying galvanized square tube,rectangular tube,angle steel,channel steel from ready ...