ASTM A220/A220M-99(2014)

1.1.1 For continuous service at temperatures up to 1200°F [650°C] design factors should be incorporated to compensate for possible property changes, as demonstrated by Marshall and Sommer² and by Pearson.1.2 Without knowledge of casting geometry and process details, no quantitative relationship can be stated between the properties of the iron in the various locations of a casting and those of a test bar cast from the same iron.

1.3 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.