big sized cold rolled-forming steel hollow section: These products are widely used in steel ... construction,mechanical big sized cold rolled-forming steel hollow section: These products are widely used in steel structural, ... engineering and communications and transport,etc. specifications:Square tube:13*13--400*400MM, WT:0.4-16. ... 0MM Rec tube:20*10--500*300MM, WT:0.4--16.0mm Round tube:Ø13-Ø76mm, WT ...