1.1 本规范 2. 包括标称（平均）壁无缝和焊接碳及合金钢管，用于低温和其他需要缺口韧性的应用。中列出了几种等级的铁素体钢 表1 。根据本规范，某些产品尺寸可能不可用，因为较厚的壁厚会对冲击性能产生不利影响。 1.2 以国际单位制或英寸磅单位表示的数值应单独视为标准。在正文中，国际单位制显示在括号中。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。 英寸磅单位应适用，除非订单中规定了本规范的“M”名称。 注1: 无量纲指示符NPS（公称管道尺寸）在本标准中已被“公称直径”、“尺寸”和“公称尺寸”等传统术语所取代 1.3 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 nominal (average) wall seamless and welded carbon and alloy steel pipe intended for use at low temperatures and in other applications requiring notch toughness. Several grades of ferritic steel are included as listed in Table 1 . Some product sizes may not be available under this specification because heavier wall thicknesses have an adverse effect on impact properties. 1.2 The values stated in either SI units or inch-pound units are to be regarded separately as standard. Within the text, the SI units are shown in brackets. 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. The inch-pound units shall apply unless the “M” designation of this specification is specified in the order. Note 1: The dimensionless designator NPS (nominal pipe size) has been substituted in this standard for such traditional terms as “nominal diameter,” “size,” and “nominal size.” 1.3 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.