ASME B16.15-2018 pdf – Cast Copper Alloy Threaded Fittings Classes 125 and 250.
7.1 Thread Form
All threads shall be in accordance with ASME H 1.20.1.
7.1.1 CountersInks and Chamfers. All internal taper pipe threads shall be countersunk or chamfered a distance not less than one-hall the pitch of the thread at an angle of approximately 45 dcg with the axis of the thread. External taper pipe threads shall be chamfered at an angle between 30 deg and 45 dcg with the axis for easier entrance in making a joint and protection of the thread. Countersinking and chamfering shall be concentric with the threads. The length of threads specified In all tables shall be measured to include the countersink or chamfer.
7.1.2 ALignment. The maximum allowable variation in the alignment of threads of all openings shall be 5.0 mm/rn (0.06 in./Ft).
7.1.3 InternaL Threading
(a) All fittings with Internal threads except as allowed in (b) shall be threaded with ASME B1.20.1 NPT threads. The reference point for gaging is the starting end of the fitting, provided the chamfer does not exceed the major diameter of the internal thread. When a chamler on the internal thread exceeds this limit, the reference point becomes the last thread scratch on the chamfer cone.
(b) Wrought couplings (Table, wrought caps (Table 7.1.3-2). and wrought bushings (Table 7.1.3-3) In sizes NPS ‘4. NPS ‘4, NPS 34, and NPS ‘/ shall have NPT or NPSC internal threads,
7.1.4 ExternaL Threading. All externally threaded fittings shall he threaded with ASME H1.20.1 NPT
threads. The reference point for gaging Is the end of the thread, provided the chamfer Is not smaller than the minor diameter of the external thread. When a chamfer on the external thread exceeds this limit, the reference point becomes the last thread scratch on the chamfer cone.
7.2 Gaging Tolerances
For taper pipe threads, the variation in threading shall be limited to one turn large or one turn small from the
gaging notch on the plug or the gaging face of the ring when using working gages. For straight pipe threads,
the variation in threading shall be limited to l turns large or 1 turns small from the gaging notch on the plug when using working gages.
The addition of ribs or tugs is permitted on threaded pipe fittings. Where ribs are used, it is recommended that their thickness be the same as specified for the metal thickness of the pipe fitting.
(a) Right-hand couplings shall not have more than two ribs.
(b) Right- and left-hand couplings shall have four or more ribs unless the left-hand opening Is clearly marked I,’ in which case the use of ribs is optional with the manufacturer.
(c) Wrought couplings do not require opening markings,
Cast pipe fittings shall be furnished with a rough exterior surface, free of sand inclusions, fins, and gate protrusic)ns
10.1 GeneraL
10.1.1 Tables of center-to-end dimensions aiu given 1o both straight and reducing pipe fittings. The SI dimensions and tolerances shown as whole or multiples of 0.5mm in tables may differ slightly in absolute value from the corresponding US. Customary dimensions in parentheses. Any dimension that is within tolerance by either SI or U.S. Customary measurement is considered to be In confor mance with this Standard.
10.1.2 The sketches of fittings accompanying Tables
7.1.3-1 through 7.1.3-3 and Tables 10.1.2-1 through
10.1.2-8 are representative and are included for the purpose of Illustration.
10.2 Reducing Fittings
10.2.1 The dimensions of reducing fittings shown in Tables 10,1.2-1 through 10.1.2-4 and Table are for use only when making patterns for the specific reducing pipe fitting in question and do not apply when a larger size pattern is reduced (Le., “bushed) to make the reduction or reductions in the fitting. Reducing pipe fitting patterns shall be designed to produce wall thicknesses and detail and dimensions as required for the sizes involved.
10.22 The transition in wall thickness from one end size to another shall be in a manner that minimizes the addi tion of stress caused by sudden changes in direction or wall thickness.