ASME B1.20.7:1991 (2018) pdf free download – Hose Coupling Screw Threads (Inch)
The minimum minor diameter of the nipple is such as to result in a flat equal to ’13 of the P/8 basic flat or P/24 at the root, when the pitch diameter of the nipple is at its minimum value. The maximum minor diameter is such as to result in a P/8 flat at the root of the nipple thread at maximum pitch diameter, but may be such as what would be produced by the use of a worn or rounded threading tool. This is the maximum minor diameter shown in Fig. 1 and is the diameter on which the minor diameter tolerance formula shown above is based. In practice, the minor diameter of an external thread is sat- isfactory when accepted by a gage or gaging method that represents the maximum material condition of the internal thread.
(a) Minor Diameter Tolerance = 2 X Pitch Diame- ter Tolerance. The minimum minor diameter of the cou- pling swivel is such as to result in a basic flat of PI8 at the crest when the pitch diameter of the coupling swivel is at its minimum value.
(b) Major Diameter Tolerance = Pitch Diameter Tolerance + 2h/9. The minimum major diameter of the coupling swivel is such as to result in a basic flat of P/8 at the root of the thread when the pitch diameter is at its minimum value.
Acceptability of product screw threads, based on the method specified, shall be in accordance with ANSI/ ASME B1.3M. Gages and gaging are in accordance with ANSI/ASME B1.2. Gage dimensions are specified in Tables 6, 7, and 8. The maximum minor diameter of the GO thread gage for external product threads is equal to the minimum minor diameter of the internal product thread. All other gage dimensions are calculated in ac- cordance with ANSUASME B1.2. Gage design shall be in accordance with American National Standard ASME/ ANSI B47.1.
NOTES:
(1 ) Dimensions for the minimum major diameter of the coupling correspond to the basic flat (lh X P), and the profile at the major diameter produced by a worn tool must not fall below the basic outline. For reference only the maximum major diameter of the coupling shall be that corresponding to a flat at the major diameter of the maximum coupling equal to ’124 X P and may be determined by adding 12/s x h (or 0.7939P) to the maximum pitch diameter of the coupling.
(2) Data on the 4-6NH(SPL) thread are included since this thread is used extensively aboard ship by the Navy Department.