ASME B16.3:2021 pdf free download

ASME B16.3:2021 pdf free download.Malleable lron Threaded Fittings Classes 150 and 300.
7.3 Tolerances
It is recognized that some variations are absolutely unavoidable In the making of patterns and castings. The following tolerances shall apply:
(a) Metal Thickness Tolerances. At no point in the casting shall the metal thickness be less than 90% of the value given in the tables
(b) Center-to-End Tolerances. Permitted tolerances on the center-to-end dimensions of the fittings are shown in Table 7.3-1. Tolerances for end-to-end dimensions and lengths of couplings and reducers shall be twice those given. The largest opening in a reducing fitting governs the tolerances to be applied to all openings. These tolerances do not apply to return bends and caps.
8 ThREADING
8.1 Types of Threads
All fittings shall he threaded according to ANSI/ASME 8L20.1, and shall have taper threads, except wrought couplings (Table 7.2.1-3) and wrought caps (Table 8.1-1) in NPS ‘4. NPS /4. and NPS which may have straight threads.
8.2 Tolerances
Variations in taper threading shall be limited to one turn brge or one turn small from the gaging face on ring and gaging notch on plug when using working gages. The variations in straight threading shall be limited to one and one-half turns large or small from the gaging notch on plug when using a taper pipe thread working gage. The reference point for gaging internal fittings threads depends on the chamfer diameter. When the Internal chamfer diameter exceeds the mapor diameter of the internal thread, the reference point is the last thread scratch on the chamfer cone. When the internal chamfer diameter does not exceed the major diameter of the internal thread, the reference point is the end of the fitting (see Figure 8.2-1).
8 Countersink or Chamfer
For the purpose of easier entrance in making a joint and for protection of the thread, all internal threads shall be countersunk a distance of not less than one-half the pitch of the thread at an angle of approximately 45 deg with the axis of the thread; all external threads shall be chamfered at an angle of 30 deg to 45 deg with the axis. Countersinking and chamfering shall be concentric with the threads.
8.4 Thread Length
The length of threads specified in all tables shall be measured to include the countersink or chamfer.
8.5 ALignment
The maximum allowable variation in the alignment of threads of all openings of threaded fittings shall be 5.0 mm/rn (0.06 in./ft) (0.5% slope).
9 RIBS
9.1 GeneraL
The addition of ribs or tugs Is permitted on threaded fittings. Where ribs are used, It is recommended that their thickness be the same as specified for metal thickness of the lilting. Right-hand couplings shall have no more than two ribs.
9.2 SpeciaL Coupungs
Right- and left-hand couplings shall have four or more ribs unless the left-hand opening is clearly marked, in which case the use of nbs is at the discretion of the manufacturer.
10 PLUGS, BUSHINGS, AND LOCKNUTS
For dimensions of plugs, bushings, and locknuts to be used in connection with Classes 150 and 300 malleable iron threaded fittings, see ASME 13 16.14.