This specification covers 9% nickel-alloy steel plates produced by the direct-quenching process. The plates are intended primarily for use in welded pressure vessels. The steel shall be killed and shall conform to the fine austenitic grain size requirement specified. The steel shall conform to the chemical requirements specified. Tension test and impact test shall be made to conform to the requirements specified.

1.1 This specification covers 9 % nickel-alloy steel plates produced by the direct-quenching process. The plates are intended primarily for use in welded pressure vessels.

1.2 The direct-quenching process consists of quenching the plates directly after rolling, without permitting the plates to cool below the critical temperature prior to initiation of the quenching operation, and subsequently tempering the plates (see Appendix X1). (Note: The direct-quenching process differs from the “conventional” process in which the plates are permitted to cool to a temperature significantly below the critical temperature, usually to ambient temperature, prior to reheating to a temperature above the upper critical temperature, then quenching, and subsequently tempering.)

1.3 If the plates are subjected to warm forming, the temperature shall not exceed 950°F [510°C].

1.4 The maximum nominal thickness of plates furnished under this specification shall not exceed 2 in. [50 mm].

1.5 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.

1.6 The values stated in either inch-pound 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.

1.7 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.