Full Description 1.1 This specification covers carbon-manganese steel shapes, plates, and bars of structural quality for use in riveted, bolted, or welded construction of buildings and for general structural purposes.1.2 Material under this specification is available in two grades:Grade Yield Strength,ksi [MPa] Thickness50 [345] 50 [345] Plates to 1 in. [25 mm] thick to 12 in. [305 mm] wideBars to 3 1/2 in. [90 mm] Shapes-Groups 1&2 55 [380] 55 [380] Plates to 1 in. [25 mm] thick to 12 in. [305 mm] wideBars to 3 in. [75 mm] Shapes-Groups 1&2 1.3 When the steel is to be welded, it is presupposed that a welding procedure suitable for the grade of steel and intended use or service will be utilized. See Appendix X3 of Specification A6/A6M for information on weldability. 1.4 The values stated in either inch-pound units or SI units are to be regarded as standard. Within the text, the SI units are shown in brackets. The values stated in each system are not exact equivalents; therefore, each system must be used independently of the other.