ASME B16.3-2021 pdf download
ASME B16.3-2021 pdf download.Malleable Iron Threaded Fittings.
4 SIZE 4.1 Nominal Pipe Size As applied in this Standard, the use of the phrase “nominal pipe size” or the designation NPS followed by a dimensionless number is for the purpose ofidentifying the end connection of fittings. The number is not neces- sarily the same as the fitting inside diameter. 4.2 Reducing Fittings For reducing tees, crosses, and Y-branches (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 Figure 4.2-1 illus- trate how the reducing fittings are read. 5 MARKING 5.1 Class 150 Fittings Each Class 150 fitting shall be marked for identification with the manufacturer’s name or trademark.
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 ofthe 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 toler- ances do not apply to return bends and caps. 8 THREADING 8.1 Types of Threads All fittings shall be threaded according to ANSI/ASME B1.20.1, and shall have taper threads, except wrought couplings (Table 7.2.1-3) and wrought caps (Table 8.1-1) in NPS 1 ∕ 8 , NPS 1 ∕ 4 , and NPS 3 ∕ 8 , which may have straight threads. 8.2 Tolerances Variationsintaperthreadingshallbelimitedtooneturn large 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 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 8.2-1).
7 DIMENSIONS AND TOLERANCES 7.1 General The tolerances in Table 7.3-1 are for center-to-end dimensions of the fittings. Center-to-end dimensions are given for both straight and reducing fittings in Tables 7.1-1 through 7.1-9, 7.2.1-1 through 7.2.1-6, and 8.1-1. The sketches of fittings shown in this Standard are representative and for the purpose of illustration. 7.2 Reducing Fittings 7.2.1 The dimensions of reducing fittings shown in Tables 7.2.1-1 through 7.2.1-6 are for use only when making patterns for the specific reducing fitting in ques- tionanddo notapplywhenalargersizepatternis reduced (i.e.,“bushed”) to make the reduction or reductions in the fitting. Reducing pipe fitting patterns shall be designed to produce wall thicknesses, detail, and dimensions as required for the sizes involved. 7.2.2 Thetransitioninwallthicknessfromoneendsize to another shall be in a manner that minimizes the addi- tion of stress caused by sudden changes in direction or wall thickness. 7.2.3 Proofofdesign shall be verified by a hydrostatic pressuretestmadeatambienttemperatureinwhichpres- sure is applied for a continuous period of no less than 1 min and ata constantminimum pressure ofno less than 5 times the pressure rating of the largest size of end connection in the reducing fitting.
