ASME B16.42-2021 pdf download

ASME B16.42-2021 pdf download.Ductile lron Pipe Flanges and Flanged Fittings Classes 150 and 300.
7.6.3 Length of Threads. The minimum length of effective thread in reducing flanges shall be at least equal to dimension “Length of Thread” of the corresponding pressure class threaded flange as shown in the tables, but does not necessarily extend to the face of the flange. See Table 7.5.2-1 for reducing threaded flanges.
7.6.4 Threading ToLerances. The gaging notch of the working gage shall come flush with the bottom of the chamfer in all threaded flanges, and shall be considered as the intersection of the chamfer cone and the pitch cone of the thread. This depth of chamfer is approximately equal to one-half the pitch of the thread. The maximum allowable thread variation is one turn large or small from the gaging notch.
7.8 Gaskets
Gaskets for Class 150 fiat face flanges shall conform to the dimensions shown in ASME B16.21. For flanges with raised face, gaskets shall conform to ASME B16.5, Nonmandatory Appendix B, Limiting Dimensions of Gaskets Other Than Ring Joint Gaskets, Group Ia.
7.9 Drains
7.9.1 Pipe Thread Tapping. Holes may be tapped in the wall of a fitting if the metal is thick enough to allow the effective thread length specified in MSS SP-45. Where thread length is insufficient or the tapped hole needs reinforcement, a boss shall be added.
7.9.2 Bosses. Where bosses are required, the diameters shall be as specified in MSS SP-45.
7.9.3 Designating Locations. The means of designating the locations of tapped holes or sockets for drains in fittings is shown in Figure 7.9.3-1.
Each possible location is designated by a letter so that the desired locations for the various types of fittings may be specified without using further sketches or descriptions.
8 TOLERANCES
8.1 WaLL Thickness
The wall thickness values for fittings listed in Tables 7.1.1-1 and 7.1.1-2 are minimums. Equipment shall be designed to produce greater nominal wall thickness so that manufacturing variances will not fall below these minimum values. See Nonmandatory Appendix B, para. B-1.2 for the basis used to establish these values.
8.2 Center to Contact Surface and Contact Surface to Contact Surface
8.2.1 Center to Contact Surface
(a) sizes NPS 10 and smaller: ±0.8 mm (±0.03 in.)
(b) sizes NPS 12 and larger: ±1.5 mm (±0.06 in.)
8.2.2 Contact Surface to Contact Surface
(a) sizes NPS 10 and smaller: ±1.5 mm (±0.06 in.)
(b) sizes NPS 12 and larger: ±3 mm (±0.12 in.)
8.3 Facings
Outside diameter, 1.5 mm (0.06 in.) raised face: ±0.8 mm (±0.03 in.)
8.4 FLange Thickness
(a) sizes NPS 18 and smaller: +3 mm, —0 (+0.12 in., —0)
(b) sizes NPS 20 and larger: +4.8 mm, —0 (+0.19 in., —0)
8.5 Bore of FLanges
8.5.1 Lapped Flanges
(a) sizes NPS 10 and smaller: +0.8 mm, —0 (+0.03 in.,
(b) sizes NPS 12 and larger: +1.5 mm, —0 (+0.0 6 in., —0)
8.5.2 Counterbore of Threaded FLanges
(a) sizes NPS 10 and smaller: +0.8 mm, —0 (+0.03 in.,
(b) sizes NPS 12 and larger: +1.5 mm, —0 (+0.06 in., —0)
8.6 DriLLing and Facing
(a) bolt circle diameter: ±1.5 mm (±0.06 in.)
(b) center to center of adjacent bolt holes: ±0.8 mm (±0.03 in.)
(c) eccentricity between bolt circle diameter and machined facing diameters:
(1) sizes NPS 21/2 and smaller: ±0.8 mm (±0.03 in.)
(2) sizes NPS 3 and larger: ±1.5 mm (±0.06 in.)
9 TESTING
9.1 GeneraL
Flanged fittings shall be hydrostatically tested in accordance with para. 9.3.
9.2 Flange Testing
Flanges are not required to be hydrostatically tested. Flanges attached to (or integral with) piping, pressure vessels, or other equipment may be subject to system hydrostatic test (see para. 3.5.3). In such cases, attention should be given to gasket selection because of possible excessive deformation of the flange.
9.3 Fitting SheLL Tests
The hydrostatic shell test for flanged fittings shall be not less than 1.5 times the 38°C (100°F) rating rounded off to the next higher 1.7 bar (25 psi) increment. The test pressure shall be 27.6 bar (400 psi) for Class 150 and 67.2 bar (975 psi) for Class 300.
(a) The test shall be made with water or with other suitable fluid provided its viscosity is no greater than that of water, at a test fluid temperature not above
52°C (125°F).
(b) The test duration shall be a minimum of 15 s for fittings NPS 2 and smaller, 60 s for fittings NPS 2 /2 through 8, and 3 mm for fittings NPS 10 and larger.
(c) No visible leakage is permitted through the pressure boundary wall.