For non-alloy steel hollow sections the steel designation consists of:
– the number of the European Standard;
– the letter S for structural steel;
– the indicator of the minimum specified yield strength for thicknesses ≤ 16 mm expressed in MPa (1 MPa = 1 N/mm2)
– the letters JR for the qualities with specified impact properties at room temperature, the characters J0 for the qualities with specified impact properties at 0°C and the characters J2 or K2 for the qualities with specified impact properties at -20°C;
– the H to indicate hollow section.