This specification covers standard requirements for ductile iron castings for pressure-retaining parts for use at elevated temperatures. Castings are classified by grades based on mechanical property requirements. These iron castings shall meet the specified values of tensile strength, yield strength, elongation and hardness. Chemical analysis shall be performed wherein the casting shall conform to the required chemical composition for carbon, silicon, and phosphorous. The material shall meet the required tensile properties, hardness, and microstructure. The iron casting shall undergo pressure test after machining. The thickness of any repaired section in relation to the size of the plug used shall be indicated. The minimum radius of repaired sections of cylinders or cones in relation to the size of plug used shall not exceed the prescribed limit. Other defective areas may also be repaired by plugging provided the minimum ligament between plugs in adjacent areas shall not be less than twice the distance from the nearest plug. Three Y-blocks shall be utilized as test coupons. The material shall undergo the following test methods: tension test, chemical analysis, yield strength test, and hardness test.