ASME B16.4:2021 pdf download

ASME B16.4:2021 pdf download Gray Iron Threaded Fittings Classes 125 and 250
6 MATERIAL Castings shall be produced to meetthe requirements of ASTM A126, Class A, B, or C. The manufacturer shall be prepared to certifythatthe producthas been so produced and that the chemical and physical properties thereof, as proved by test specimens, are equal to these require- ments.
7 DIMENSIONS AND TOLERANCES
7.1 General Center-to-end dimensions in millimeters are given for standard straight and reducing fittings in Tables 7.1-1 through 7.1-5. The sketches of fittings that accompany the tables are representative and for the purpose ofillus- tration.
7.2 Reducing Fittings
7.2.1 The dimensions of reduced fittings shown in Tables 7.1-2 and 7.1-3 are for use only when making patterns for the specific reducing fitting in question and do not apply when a larger size pattern is reduced (i.e., “bushed”) to make the reduction or reductions in the fitting. Reducing pipe fitting patterns shall be designedto produce wall thicknesses, detail, and dimensions asrequired for the sizes involved.
7.2.2 The transition in wall thickness from oneend sizeto another shall be in a manner that minimizes the addi-tion of stress caused by sudden changes in direction orwall thickness.
7.2.3 Proof of design shall be verified by a hydrostaticpressure test made at ambient temperature in which pres-
sure is applied continuously for no less than 1 min apd atno less than 5 times the pressure rating of the largest size
of end connection in the reducing fitting.Testing is consid-
ered successful only when no evidence of cracking, frac-
turing or leakage is exhibited after holding for at least theminimum time at or above the required pressure.
7.3 Tolerances
The following tolerances shall be permitted:
(a) Metal Thickness Tolerances. At no point in the cast-ings shall the metal thickness be less than 90% ofthe valuegiven in Table 7.1-1,7.1-4,or 7.1-5.
(b) Center-to-End Tolerances. Permitted tolerances onthe center-to-end dimensions of the fittings are shown inTable 7.3-1.Tolerances for end-to-end dimensions and
lengths of couplings and reducers shall be twice thosegiven.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.
8THREADING
(a) All fittings shall be threaded according to ASMEB1.20.1,and the variations in threading shall be
limited to one turn large or one turn small from thegaging notch on the plug when using working gages.
(b) The reference point for gaging internal fittingsthreads depends on the chamfer diameter. When theinternal chamfer diameter exceeds the major diameterof the internal thread, the reference point is the lastthread scratch on the chamfer cone. When the internalchamfer diameter does not exceed the major diameterof the internal thread, the reference point is the end ofthe 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).
9 RIBS
(a) The addition of ribs or lugs is permitted on threadedfittings. Where ribs are used, it is recommended that theirthickness be the same as specified for metal thickness ofthe fitting.
(b) Right-hand couplings shall have not more than tworibs.
(c) Right- and left-hand couplings shall have four ormore ribs unless the left-hand opening is clearlymarked, in which case the use of ribs is at the discretionof the manufacturer.
1o PLUGs,BUSHINGS,AND LOCKNUTs
For dimensions of plugs. bushings, and locknuts to beused in connection with Classes 125 and 250 gray ironthreaded fittings, see ASME B16.14.
1 FACE BEVEL
A bevel not exceeding 5 deg is permitted on the faces offitting openings. Center-to-end, end-to-end, and width-of-band dimensions may include or exclude the bevel.
12 cOATINGS
when gray iron fittings are zinc coated, they shall be hotdipped in accordance with ASTM A153/A153M or have anelectrodeposited zinc coating conforming to ASTM B633,Type I, Service Condition 4.Hot-dipped coatings shall havea minimum thickness of 0.0864 mm (0.0034 in.) and shallbe applied before threading. Electrodeposited zinc shallhave a minimum thickness of 0.025 mm (o.001 in.) andmay be applied either before or after threading.