seamless square and rectangular steel tube 1.steel grade: Q195-Q345,S235-S355 2. standard: ASTM ... A53, ASTM A252, ASTM A500, ASTM A178,ASTM A179,ASTM A106,ASTM A795, BS1387, BS1139, EN10255,EN10210, EN10219, EN10217, EN39, ... K55, API N80, API L80, API P110, St37, GR.A, A25, A25P, A, B, X42, X46, X52, X56, X60, X65, X70, ... Stable Quality and Trustful Serviceseamless square and rectangular steel tube