... -600*600mm. 5.Surface:Black painting or oiled steel square tube 1)Thickness:0.5-30mm2)Size(dia.): 15*15--600*600mm3 ... 5)Standard: ASTM BS GB JIS APISize(O.D)Wall thickness (W.T.)15mm*15mm-600mm*600mm0.5mm-30mmLength2m-12m ,by ... ,Shipbuilding, Bridging ,Automobile chassisWater Pipelines, Waste waterlines , Water supply mainsDeep tube wells casing pipes, Gas/Natural gas pipe lines, Oil pipe ...