1.1 本规范涵盖以下等级的钽和钽合金无缝管和焊接管: 1.1.1 UNS R05400级- 非合金钽，粉末冶金固结， 1.1.2 UNS R05200级- 真空熔炼的非合金钽， 1.1.3 UNS R05252级- 钽 + 2.5 % 钨合金，真空熔炼。 1.1.4 UNS R05255级- 钽 + 10 % 钨合金，真空熔炼。 1.1.5 UNS R05240级- 钽合金，60 % 钽，40 % 铌、电子束炉、真空电弧熔炼或两者兼有。 1.2 以英寸-磅为单位的数值应视为标准值。括号中给出的值是到国际单位制的数学转换，仅供参考，不被视为标准值。 1.3 本国际标准是根据世界贸易组织技术性贸易壁垒（TBT）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》中确立的国际公认标准化原则制定的。 ====意义和用途====== 12.1 为了确定是否符合规定的性能要求限值，观察值或计算值应按照惯例的四舍五入方法进行四舍五入 E29年 .

1.1 This specification covers tantalum and tantalum alloy seamless and welded tubes of the following grades: 1.1.1 UNS Grade R05400— Unalloyed tantalum, powder-metallurgy consolidation, 1.1.2 UNS Grade R05200— Unalloyed tantalum, vacuum melted, 1.1.3 UNS Grade R05252— Tantalum + 2.5 % tungsten alloy, vacuum melted. 1.1.4 UNS Grade R05255— Tantalum + 10 % tungsten alloy, vacuum melted. 1.1.5 UNS Grade R05240— Tantalum alloy, 60 % tantalum, 40 % niobium, electron-beam furnace, vacuum arc melt, or both. 1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard. 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. ====== Significance And Use ====== 12.1 For the purpose of determining compliance with the specified limits of property requirements, an observed value or a calculated value shall be rounded in accordance with the rounding method of Practice E29 .