This specification covers carbon steel shapes@ plates@ and bars of structural quality for use in riveted@ bolted@ or welded construction of bridges and buildings@ and for general structural purposes. Supplemental Requirements are provided where improved internal quality and notch toughness is important. These shall apply only when specified by the purchaser in the order@ except that Supplementary Requirement S5 is mandatory for material designated on the contract drawings as main load carrying member components subject to tensile stress. 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. The purchaser should consider specifying supplemental requirements@ such as fine austenitic grain size and Charpy V-Notch Impact requirements@ when Group 4 or Group 5 wide flange shapes are specified for use in other than column or compression applications. This specification is applicable to orders in either SI units (as M 183M) or inch-pound units (as M 183). SI units and inch-pound units are not necessarily equivalent. Inch-pound units are shown in brackets in the text for clarity@ but they are the applicable values when the material is ordered to M 183.