This guide covers standard specification for three classes of gray iron for castings intended for use as valve pressure retaining parts, pipe fittings, and flanges. Chemical analysis shall be performed in each lot and shall conform to the required chemical composition for phosphorous and sulfur. Tension test shall be conducted on each class of gray iron castings and shall conform to the specified values of tensile strength. Tension test specimens shall have threaded ends and shall conform to the prescribed dimensions.