ASME B16.3-2011 pdf – Malleable lronThreaded Fittings Classes 150 and 300.
(d) Class 300 street elbows are not recommended Iw pressures above NM) psi.
4.1 Nominal Pipe Size
As applied in this Standard, the use ot the phrase “nominal pipe size” or the designation NPS followed by a dimensionless number is for the purpose of identilying the end connection of fittings. The number is not necessarily the same as the fitting inside diameter.
4.2 ReducIng Fittings
For reducing tees, crosses, and Y-hrandies (laterals), the size of the largest run opening shall be given first, followed by the size of the opening at the opposite end of the run. Where the fitting is a tee or Y-branch (lateral). the size of the outlet is given last. Where the fitting is a cross, the largest side-outlet opening is the third dimension given, followed by the opposite opening. The straight-line sketches of Fig. I illustrate how the reducing fittings are read.
5.1 Class 150 Fittings
Each Class 15 titling shall he marked for identihca• lion with the m.inulacturer’s name or trademark.
(a) MkaI Thickness Toknrnces. Metal thickness at no point in the castings shall be less than 90% of the value given in the tables.
(b) Crnler-to-Erid Toknmcrs. Permitted tolerances on the center-to-end dimensions of the fittings arc shown in Tables 2 and 1.2. 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 retLirn bends and caps.
8.1 TVpes of Threads
All fittings shall be threaded according to ANSI/ASME K1.20.1. and shall have taper threads. except wrought couplings (Tables $ and I-K) and wrought caps (Tables 9 and 1-9) in NPS ‘4 ‘4. and . which may have straight threads.
8.2 Tolerances
Variations in taper threading shall be limited to one him large or one him 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-hall 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 upon the chamfer diameter. When the internal chamfer diameter exceeds the major diameter of the internal thread, the reference point is the last thread scratch on the chamtr 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 Fig. 2).
8.3 CountersInk or Chamler
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 chamlering 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 ln./ft) (0.5% slope).