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1.1 This specification covers chromium-molybdenum-tungsten alloy steel forgings intended primarily for use in boilers and pressure vessels for elevated temperature service.
1.1.1 Elevated temperatures are temperatures in the range where creep and stress rupture properties are important for the alloy steels in this specification.
1.2 Supplementary requirements are provided both in this specification and in the General Requirements Specification A 788/A 788M for use when additional testing or inspection is desired. These shall apply only when specified individually by the purchaser in the purchase order or contract.
1.3 Unless the order specifies the applicable "M" specification designation, the forgings shall be supplied to the inch-pound units.
1.4 The values stated in either inch-pound or SI (metric) units are to be regarded separately as standard. Within the text and tables, the SI units are shown in brackets. 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 specification.
2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.
A275/A275M Practice for Magnetic Particle Examination of Steel Forgings
A388/A388M Practice for Ultrasonic Examination of Steel Forgings
A788/A788M Specification for Steel Forgings, General Requirements
A966/A966M Practice for Magnetic Particle Examination of Steel Forgings Using Alternating Current
ICS Number Code 77.140.30 (Steels for pressure purposes)