1.1 This specification covers continuous grain flow forged carbon and alloy steel crankshafts for medium speed diesel and natural gas engines. 1.2 The steel used in the manufacture of the forgings is required to be vacuum degassed. 1.3 Provision is made for treatment of designated surfaces of the crankshaft to provide enhanced fatigue strength, or wear resistance, or both. 1.4 The values stated in either inch-pound units or SI (metric) units are to be regarded separately as standards. Within the text and tables 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. Combining values from the two systems may result in nonconformance with the specification. 1.5 Unless the order specifies the applicable "M" specification designation, the material shall be furnished to the inch-pound units. 1.6 Except as specifically required in this specification, all provisions of Specification A 788 apply.