本标准规定了统一螺纹的螺纹形式、系列、等级、公差、公差和名称。（为了强调统一螺纹基于英制模块，它们可以表示为统一英制螺纹。）为统一螺纹开发了几种不同的螺纹形式；然而，本标准仅涵盖[Unified]UN和UNR[external threads only]螺纹形式。为便于参考，本标准的公制翻译已并入非强制性附录C。非强制性附录a至E包含对本标准各节的补充有用信息。

This Standard specifies the thread form, series, class, allowance, tolerance, and designation for unified screw threads. (In order to emphasize that unified screw threads are based on inch modules, they may be denoted unified inch screw threads.) Several variations in thread form have been developed for unified threads; however, this Standard covers only [Unified] UN and UNR [external threads only] thread forms. For easy reference, a metric translation of this Standard has been incorporated as Nonmandatory Appendix C. Nonmandatory Appendices A through E contain useful information that is supplementary to the sections of this Standard.