1.1 本规范涵盖适用于高温或腐蚀性环境的电熔焊接管道，如 表1 （尽管本规范对可提供的管道尺寸没有任何限制，但商业惯例通常仅限于公称直径不小于8英寸[203毫米]的尺寸。） 1.2 包括以下五类管道: 1.2.1 1级-- 管道应通过在所有焊道中使用填充金属的工艺进行双面焊接，并应进行完全射线照相。 1.2.2 2级-- 管道应通过在所有焊道中使用填充金属的工艺进行双面焊接。 不需要射线照相。 1.2.3 3级-- 管道应通过在所有焊道中使用填充金属的工艺进行单焊，并应进行完全射线照相。 1.2.4 4级-- 与第3类相同，但暴露在管道内表面的焊道可在不添加填充金属的情况下进行。 1.2.5 5级-- 管道应通过在所有焊道中使用填充金属的工艺进行双面焊接，并应进行点射线照相。 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不一定是完全相等的；因此，为了确保符合标准，每个系统应独立使用，并且不得将两个系统的值组合使用。 1.4 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熟悉所有危险，包括制造商提供的本产品/材料的适当安全数据表（SDS）中确定的危险，制定适当的安全、健康和环境实践，并在使用前确定监管限制的适用性。 1.5 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 covers electric fusion welded pipe suitable for high-temperature or corrosive service as listed in Table 1 . (Although no restrictions are placed on the sizes of pipe that may be furnished under this specification, commercial practice is commonly limited to sizes not less than 8 in. [203 mm] nominal diameter.) 1.2 Five classes of pipe are covered as follows: 1.2.1 Class 1— Pipe shall be double welded by processes employing filler metal in all passes and shall be completely radiographed. 1.2.2 Class 2— Pipe shall be double welded by processes employing filler metal in all passes. No radiography is required. 1.2.3 Class 3— Pipe shall be single welded by processes employing filler metal in all passes and shall be completely radiographed. 1.2.4 Class 4— Same as Class 3 except that the weld pass exposed to the inside pipe surface may be made without the addition of filler metal. 1.2.5 Class 5— Pipe shall be double welded by processes employing filler metal in all passes and shall be spot radiographed. 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 are not necessarily exact equivalents; therefore, to ensure conformance with the standard, each system shall be used independently of the other, and values from the two systems shall not be combined. 1.4 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 become familiar with all hazards including those identified in the appropriate Safety Data Sheet (SDS) for this product/material as provided by the manufacturer, to establish appropriate safety, health, and environmental practices, and determine the applicability of regulatory limitations prior to use. 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.