Square Tube Dimension: 20mm*20mm-1000*1000mm Rectangular Tube Dimension: 20mm*30mm-600mm*1000mm Thickness:2mm-35mm Length:6m-12m , or as per customerâ??s requirements Standards: DIN EN10210,EN10219,GB/T3094-2000,ASTM A500,JIS G 3466,GB/T6728-2002 Steel Grades:Q195, Q235, Q345(16Mn), STKR400/490, A500, ST37/44/52, S235, S275, S355, etc. Surface Treatment: anti-rust oil, black painting, galvanizing Packing: in bundles with steel strips or in bulk as per customer request Applications: Construction framework, trestle, motorcar cassis,flight terminal framework, shipbuilding, automobile axle pipe, MRT and so on The mostly used sizes ( for seamless and welded square steel pipe) are as below: 30 * 30 *( 2-4mm) â??â?? 50 * 50 *( 2-5mm) â??â?? 80 * 80 *( 3-10mm). 100 * 100 *( 3-16mm) â??â?? 135 * 135 *( 4-16mm) â??â?? 140 * 140 *( 4-18mm). 150 * 150 *( 4-20mm) â??â?? 180 * 180 *( 5-20mm) â??â?? 220 * 220 *( 6-20mm). 250 * 250 *( 5-25mm) â??â?? 300 * 150 *( 6-20mm) â??â?? 300 * 180 *( 8-20mm). 500 * 500 *( 8-25mm) â??â?? 400 * 400*( 8-22mm) â??â?? 450 * 450 *( 8-22mm). 300 * 200 *( 6-20mm) â??â?? 350 * 300 *( 8-22mm) â??â?? 350 * 350 *( 8-22mm). 400 * 250 *( 8-25mm) â??â?? 450 * 300 *( 8-25mm) â??â?? 450 * 480 *( 9-25mm). 500 * 300 *( 8-25mm) â??â?? 600*400*(8-30mm)