【国外标准】 Standard Specification for Ferritic Ductile Iron Pressure-Retaining Castings for Use at Elevated Temperatures

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.1.1 This specification covers ductile iron castings for pressure-retaining parts for use at elevated temperatures. Castings of all grades are suitable for use up to 450 °F. For temperatures above 450 °F and up to 650 °F, only Grade 60-40-18 castings are suitable (Note 1).1.2 Valves, flanges, pipe fittings, pumps, and other piping components are generally manufactured in advance and supplied from stock by the manufacturer, jobber, or dealer.1.3 For supplemental casting requirements, Specification A834 may be utilized.1.4 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 nonconformance with the standard.NOTE 1: For service other than as specified in this section, reference should be made to Specification A536 for Ductile Iron Castings.21.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.