ASME B16.3:2021 pdf download

ASME B16.3:2021 pdf download.Malleable Iron Threaded Fittings
1 SCOPE
This Standard covers malleable iron threaded fittings, Classes 150 and 300. It also contains provisions for using steel for caps and couplings in Class 150 for NPS 3 ∕ 8 and smaller. This Standard includes (a) pressure–temperature ratings (b) size and method ofdesignating openings ofreduc- ing fittings (c) marking (d) material (e) dimensions and tolerances (f) threading (g) coatings
2 GENERAL
2.1 References Standards and specifications adopted by reference in this Standard are shown in Mandatory Appendix I. It is not considered practical to identify in the text the specific edition of each referenced standard and specification. Instead, the specific editions of the referenced standards and specifications are listed in M andatory Appendix I. 2.2 Quality Systems Requirements relating to the product manufacturers’ quality system programs are described in Nonmandatory Appendix A. 2.3 Relevant Units This Standard states values in both SI (metric) and U.S. Customary units. These systems of units are to be regarded separately as standard. In this Standard, the U.S. Customary units are shown in parentheses. The values stated in each system are not exact equivalents; therefore, it is required that each system of units be used independently of the other. Combining values from the two systems constitutes nonconformance with this Standard. 2.4 Service Conditions Criteria for selection ofmaterials suitable forparticular fluid service are not within the scope of this Standard.2.5 Convention For determining conformance with this Standard, the convention for fixing significant digits where limits (maximum and minimum values) are specified shall be as defined in ASTM E29. This requires that an observed orcalculatedvalueberoundedofftothenearestunitinthe lastright-hand digitused forexpressingthe limit. Decimal values and tolerances do notimply a particular method of measurement. 2.6 Denotation 2.6.1 Pressure Rating Designation. Class, followed by a dimensionless number, is the designation for pressure– temperature ratings as follows: Class 150 and Class 300.
3 PRESSURE–TEMPERATURE RATINGS
(a) Pressure–temperature ratings for these fittings are shown in Table 3-1. (b) All ratings are independent of the contained fluid and are the maximum allowable working gage pressures at the tabulated temperatures. Intermediate ratings may be obtained bylinear interpolation between the tempera- tures shown. (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. (d) Class 300 street elbows are not recommended for pressures above 600 psi.
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.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.