This specification covers gray iron for castings suitable for pressure-containing parts at elevated temperatures. Castings shall be stress-relieved by placing them in a suitable furnace and heating them uniformly to the temperatures and for the times specified. Castings to be used at a particular temperature range shall undergo heat treatment and cooling. Chemical analysis shall be performed on each class of castings and shall meet the maximum requirement for carbon, phosphorus and sulfur. Iron used in supplying castings shall conform to the required tensile strength. Separately cast test bars having the required dimensions shall be poured from the same lot as the castings represented. The test bars shall be cast in dried siliceous sand molds maintained at approximately room temperature. Tension test shall be performed on each lot and materials shall conform to the tensile requirements specified.

1.1 This specification covers gray iron for castings suitable for pressure-containing parts for use at temperatures up to 650°F (350°C).

1.2 Classes of Iron:

1.2.1 Castings of all classes are suitable for use up to 450°F (230°C). For temperatures above 450°F and up to 650°F, only Class 40, 45, 50, 55, and 60 castings are suitable.

1.2.2 Castings of all clases are suitable for use up to 230°C. For temperatures above 230°C and up to 350°C, only Class 275, 300, 325, 350, 380, and 415 castings are suitable.