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