ASME B16.4-2021 pdf – Gray IronThreaded Fittings Classes 125 and 250.
(c) The temperatures shown for the corresponding pressure rating shall be the material temperature of the pressure-retaining structure. It may be assumed that the material temperature is the same as the fluid temperature. Use of a pressure rating at a material temperature other than that of the contained fluid Is the responsibility of the user and subject to the require— ments of any applicable code.
4.1 NominaL Pipe Size
As applied in this Standard, the use of the phrase noniinal pipe size’ or hc designation NPS followed by a dimensionless number Is for the purpose of Identifying the end connection of flttIngs The number is not necessarily the same as the Fitting inside diameter.
42 Reducing Fittings
For reducing tees and crosses, 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, 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 Figure 4.2-1 illustrate how the reducing fittings are read.
(a) Each Class 125 fitting shall be marked for Identification with the manufacturer’s name or trademark.
7.2.2 The transition in wall thickness from one end size to another shall be in a manner that nii,iimizes the addilion of stress caused by sudden changes In direction or wall thickness.
7.23 Proof of design shall be verified by a hydrostatic pressure test made at ambient temperature in which pressure is applied continuously for no less than I mm and at no less than 5 times the pressure rating of the brgest size of end connection in the reducing fitting. Testing is considered successful only when no evidence of cracking. Iracturing. or leakage is exhibited after holding for at least the minimum time at or above the required pressure.
7.3 Toterances
The following tolerances shall be permitted:
(a) Metal Thickness Tolerances. At no point in the castings shall the metal thickness be less than 90% ol the value given in Table 7.1-1, 71-4. or 7.1-5.
(b) Center-to-End Toleraricei 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.
(o, All fittings shall be threaded according to ASME 131,20.1, and the variations In threading shall be limited to one turn large or one turn small from the gaging notch on the plug when using working gages.
(b) The reference point for gaging internal fittings threads depends on 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 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 8-1).
(c) For the purpose of easier entrance in making a jointand for protection of the thread, all threads shall be coun-tersunk a distance of not less than one-half the pitch of thethread at an angle of approximately 45 deg with the axis ofthe thread. Countersinking shall be concentric with thethreads.
(d) The length of the threads specified in all tables shallbe measured to include the countersink.
(e) The maximum allowable variation in the alignmentof threads of all openings of threaded fittings shall be5.0 mm/m(0.06 in./ft)(0.5% slope).