This specification covers manganese-molybdenum and manganese-molybdenum-nickel alloy steel plates intended particularly for welded boilers and other pressure vessels. According to their strength levels, the plates are available in four grades: Grades A, B, C, and D. The maximum thickness of plates is limited only by the capacity of the chemical composition to meet the specified mechanical property requirements. The steel shall be killed and shall conform to fine grain size requirements. The plates shall be subjected to tension test to determine the tensile strength, yield strength, and elongation.

1.1 This specification2 covers manganese-molybdenum and manganese-molybdenum-nickel alloy steel plates intended particularly for welded boilers and other pressure vessels.

1.2 Plates under this specification are available in four grades having different strength levels as follows:

Grade

Tensile Strength,
ksi [MPa]

Type

A

75–95 [515–655] 

manganese-molybdenum

B

80–100 [550–690]

manganese-molybdenum

C

80–100 [550–690]

manganese-molybdenum-nickel

D

80–100 [550–690]

manganese-molybdenum-nickel

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

1.4 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 the specification.

1.5 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.