This specification covers specially heat treated 5% and 5 1/2% nickel alloy steel plates intended primarily for welded pressure vessels for service at low or cryogenic temperatures. Plates are classified as Grade A and Grade B. The steel shall be killed and shall conform to the fine austenitic grain size requirements specified. Plates shall be heat treated in accordance with the required specifications. The steel shall conform to the chemical requirements specified. Tensions tests and impacts tests shall be made to meet the mechanical requirements specified.

1.1 This specification covers austenitized, quenched, temperized, and reversion-annealed 5% nickel alloy steel plates intended primarily for welded pressure vessels for service at low or cryogenic temperatures.

1.2 The maximum thickness of plates which can be supplied under this specification is limited only by the capacity of the material to meet the specified requirements.

1.3 This material is susceptible to magnetization. Use of magnets in handling after heat treatment should be avoided if residual magnetism would be detrimental to subsequent fabrication or service.

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.