This standard relates to screw threads of buttress form and provides: (a) A form of 7'/45" buttress thread with 0.6p basic height of thread engagement (see Fig. la). (b) A table of preferred diameter-pitch combinations (see Table 1). (c) A formula for calculating pitch diameter tolerances (see Par. 6.1). (d) Tolerances for major and minor diameters (see Par. 6.2 and 6.3). (e) A system of allowances between external and internal threads (see Par. 7). (f) Recommended methods of measuring and gaging (see Par. 10 and 11). (g) Dimensional acceptability of buttress product (see Section 12).