scope:

This specification covers gray iron castings intended for general engineering use where tensile strength is a major consideration. Castings are classified on the basis of the tensile strength of the iron in cast test bars.

This specification subordinates chemical composition to tensile strength.

Castings produced to this specification are graded on the basis of minimum tensile strength obtained in special test coupons designed to standardize cooling rate. The tensile strength developed in certain casting sections may vary from test coupon values. (See X1.2.)

The values stated in SI units are to be regarded as the standard.

AASHTO M 306 may be specified for drainage structure castings such as frames, grates, rings, and covers for inlets, manholes, and other structures if loading requirements exceed normal highway loading or if more restrictive dimensional tolerances are required.