1.1 本规范 2. 涵盖用于压力容器（如反应堆系统中使用的压力容器）的淬火和回火真空处理碳钢和合金钢锻件。具体而言，它涵盖了容器封盖、壳体、法兰、管板、环、封头和类似零件的锻件。 1.2 所有等级均视为可在适当条件下焊接。焊接技术至关重要，且焊接程序和检查应符合所用材料等级的批准方法。 1.3 以国际单位制或英寸磅单位表示的数值应单独视为标准。每个系统中规定的值可能不是完全相等的；因此，每个系统应独立使用。将两个系统的值合并可能导致不符合标准。 1.4 除非订单规定了适用的“M”规格名称，否则材料应按英寸提供- 磅单位。 注1: 1级和1A级由不同的化学成分组成，但具有相同的机械要求。 注2: 名称更改如下: 现在的 以前 一年级 1级 1A级 1A级 二年级一班 2级 二年级二班 2A级 三年级一班 3级 三年级二班 3A级 4N级1级 4级 4N级2级 4A级 4N级3级 4B级 五年级一班 5级 五年级二班 5A级 22年级3班 22B级 22年级4、5、6和7班 3V级 3V级 1.5 本标准并非旨在解决与其使用相关的所有安全问题（如有）。本标准的使用者有责任在使用前制定适当的安全、健康和环境实践，并确定监管限制的适用性。 1.6 本国际标准是根据世界贸易组织技术性贸易壁垒委员会发布的《关于制定国际标准、指南和建议的原则的决定》中确立的国际公认的标准化原则制定的。

1.1 This specification 2 covers quenched and tempered vacuum-treated carbon and alloy steel forgings for pressure vessels such as those used in reactor systems. Specifically, it covers forgings for vessel closures, shells, flanges, tube sheets, rings, heads, and similar parts. 1.2 All grades are considered weldable under proper conditions. Welding technique is of fundamental importance, and it is presupposed that welding procedure and inspection will be in accordance with approved methods for the grade of material used. 1.3 The values stated in either SI units or inch-pound units are to be regarded separately as standard. 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 non-conformance with the standard. 1.4 Unless the order specifies the applicable “M” specification designation, the material shall be furnished to the inch-pound units. Note 1: Grades 1 and 1A are composed of different chemistries but have the same mechanical requirements. Note 2: Designations have been changed as follows: Current Formerly Grade 1 Class 1 Grade 1A Class 1A Grade 2 Class 1 Class 2 Grade 2 Class 2 Class 2A Grade 3 Class 1 Class 3 Grade 3 Class 2 Class 3A Grade 4N Class 1 Class 4 Grade 4N Class 2 Class 4A Grade 4N Class 3 Class 4B Grade 5 Class 1 Class 5 Grade 5 Class 2 Class 5A Grade 22 Class 3 Class 22B Grade 22 Classes 4, 5, 6, and 7 Grade 3V Class 3V 1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. 1.6 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.