scope:

1.1 This is an acceptance specification for the magnetic particle inspection of forged steel crankshafts having main bearing journals or crankpins 4 in. [200 mm] or larger in diameter.

1.2 There are three classes, with acceptance standards of increasing severity:

1.2.1 Class 1.

1.2.2 Class 2 (originally the sole acceptance standard of Specification A456).

1.2.3 Class 3 (formerly covered in Supplementary Requirement S1 of Specification A456-64 (1970)).

1.3 This specification is not written to cover diesel locomotive crankshafts specifically, but Class 2 or 3 may be applied if manufacturer and ultimate user agree to its use.

Note-Specification A668/A 688M is a product specification which may be used for crankshaft forgings.

1.4 The values stated in either inches or SI (metric) units are to be regarded separately as the standard. Within the text and figures, the SI units are shown in brackets. The values stated in each system are not exact equivalents; therefore each system shall 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 units.