1.1 This specification covers chromium-molybdenum alloy steel plates intended primarily for welded boilers and pressure vessels designed for elevated temperature service.

1.2 Plates are available under this specification in several grades having different alloy contents as follows.

1.3 Each grade except Grade 91 is available in two classes of tensile strength levels as defined in the Tensile Requirements tables. Grade 91 is available only as Class 2. Grade 91 consists of two types, with Type 2 differentiated from Type 1 by requiring restricted composition for the enhancement of creep resistance.

NOTE 1: Grade 911, previously covered by this specification, is now covered by Specification A1017/A1017M.

1.4 The maximum thickness of plates is limited only by the capacity of the composition to meet the specified mechanical property requirements.

1.5 The values stated in either inch-pound units or SI units are to be regarded separately as standard. Within the text, the SI units are shown in brackets. The values stated in each system are not exact equivalents. Therefore, each system must be used independently of the other. Combining values from the two systems may result in nonconformance with this specification.

ASTM Standards

A20/A20M Specification for General Requirements for Steel Plates for Pressure Vessels
A370 Test Methods and Definitions for Mechanical Testing of Steel Products
A435/A435M Specification for Straight-Beam Ultrasonic Examination of Steel Plates
A577/A577M Specification for Ultrasonic Angle-Beam Examination of Steel Plates
A578/A578M Specification for Straight-Beam Ultrasonic Examination of Rolled Steel Plates for Special Applications
A1017/A1017M Specification for Pressure Vessel Plates, Alloy Steel, Chromium-Molybdenum-Tungsten