ASME B1.20.7:1991 pdf free download.HOSE COUPLING SCREW THREADS (INCH).
3.1 For Nipple (External) Threads (except NHR)
(a) Major Diameter Tolerances — 2 x Pitch Diameter Tolerance
(b) Minor Diameter Tolerance = Pitch Diameter Tolerance + 2h19 (h Bdsic Thread Height. Sec Fig.
The minimum minor diameter of the nipple is such as to result in a flat equal to ½ of the P18 basic flat or P124 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 P18 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 formu’a shown above is based. In practice, the minor diameter of an external thread is satisfactoiy when accepted by a gage or gaging method that represents the maximum material condition of the internal thread.
3.2 For Coupling Swivel (Internal) Threads (except NHR)
(a) Minor Diameter Tolerance = 2 X Pitch Diameter Tolerance. The minimum minor diameter of the coupling swivel is such as to result in a basic flat of P/8 at the crest when the pitch diameter of the coupling swivel is at its minimum value.
(b) Major Diameter Tolerance Pitch Diameter Tolerance + 2h19. The minimum major diameter of the coupling swivel is such as to result in a basic flat of P18 at the root of the thread when the pitch diameter is at its minimum value.
4 ACCEPTABILITY
Acceptability of product screw threads, based on the method specified, shall be in accordance with ANSI/ ASME BI.3M. Gages and gaging are in accordance with ANSI/ASME BI.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 accordance with ANSIIASME 81.2. Gage design shall be in accordance with American National Standard ASME/ANSI 847.1.
ASME B1.20.7:1991 pdf free download
