Hot Rolled Square Welded Steel Tube , PrefabricateSteel Tube Standard: (GB/T6728-2002) Material grade: (1) Q235: According to standard GB700-2006 (2) Q345: According to standard GB700-2008 Length:Length could be customized, which is usually within 4,000mm-12,000mm. If you need some special length, it may be discussed by both parties. Specification: Please refer to the form below.: