ASME International

Buttress Inch Screw Threads 7 Degrees/45 Degrees Form with 0.6 Pitch Basic Height of Thread Engagement
 N B1.9

Annotation

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. 1a).

(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).

APPENDIXES

The following appendixes are included in this standard:

(1) Pitch Diameter Equivalents for Lead and Flank Angle Deviations

(2) Pitch Diameter-Measurement for External and Internal Buttress Threads

(3) 7°/45° British Standard Buttress Thread with 0.4p Basic Height of Thread Engagement.

The intent of this standard is not to preclude the use of other measuring or gaging systems provided they are properly correlated.