JIS – Japanese Industrial Standard JIS G3444 Steel grade: STK 30, STK 41, STK 50, STK 51, STK 55 Application: Carbon Steel Tubes for General Structural Purpose Dimension Range: 21.7-1016.0 mm Nominal Size Outside Diameter mm. Thickness mm. Weight (plain end) kg/m. mm. 15 21.70 2.00 0.98 20 27.20 2.00 2.30 1.24 1.41 25 34.00