GB/T 3103.4-1992 in English

《GB/T 3103.4-1992紧固件公差 耐热用螺纹连接副》由TC85（全国紧固件标准化技术委员会）归口，主管部门为中国机械工业联合会。
本标准规定了螺纹规格为M12~180×6、产品等级为TA、TB和TC级的等长双头螺柱、双头螺柱、六角头螺栓、六角法兰面螺栓、六角螺母、罩螺母及公称直径dw=21~270的受力套管的公差及表面粗糙度。本标准适用于既能承受高温、交变载荷，又要在相当大的程度上保持预紧力和耐疲劳强度的工况条件下使用的紧固件。

Scope

This standard specifies the equal-length stud studs, stud studs, hexagon head bolts, hexagon flange face bolts, hexagon nuts, and cover nuts with thread specifications M12～180×6 and product grades of TA, TB, and TC. And the tolerance and surface roughness of the stressed casing with nominal diameter dw=21~270. This standard is applicable to the fasteners used under the working conditions that can not only bear high temperature and alternating load, but also maintain the preload and fatigue strength to a considerable extent. Note: Product grade is determined by product quality and tolerance size, TA grade is the most accurate, TC grade is the least accurate.