ASME B16.3-2006 pdf download.Malleable Iron Threaded Fittings Classes 150 and 300.
3 SIZE 3.1 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. 3.2 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 Fig. 1 illustrate how the reduc- ing fittings are read. 4 MARKING 4.1 Class 150 Fittings Each Class 150 fitting shall be marked for identifica- tion with the manufacturer’s name or trademark. 4.2 Class 300 Fittings Each Class 300 fitting shall be marked for identifica- tion with (a) the manufacturer’s name or trademark (b) the numerals “300” (c) the letters “MI” to designate malleable iron (d) the size (e) other markings as permitted by MSS SP-25 5 MATERIAL 5.1 Malleable Iron The chemical and physical properties of the castings shall be in accordance with ASTM A 197. The manufac- turer shall be prepared to certify that the product has been so produced. 5.2 Steel Class 150 couplings and caps in NPS 1 ⁄ 8 , 1 ⁄ 4 , and 3 ⁄ 8 may be made from steel rod or bar with a minimum yield strength of 30 ksi at the manufacturer’s option.
7 THREADING 7.1 Types of Threads All fittings shall be threaded according to ASME B1.20.1 and shall have taper threads, except wrought couplings (Tables 8 and I-8) and wrought caps (Tables 9 and I-9) in NPS 1 ⁄ 8 , 1 ⁄ 4 , and 3 ⁄ 8 , which may have straight threads. 7.2 Tolerances Variations in taper threading shall be limited to one turn 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 lim- ited 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 upon 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 Fig. 2.) 7.3 Countersink or Chamfer For the purpose of easier entrance in making a joint and for protection ofthe thread, all internal threads shall be countersunk a distance of not less than one-half the pitch of the thread at an angle of approximately 45 deg with the axis of the thread; all external threads shall be chamfered at an angle of 30 deg to 45 deg with the axis. Countersinking and chamfering shall be concentric with the threads. 7.4 Thread Length The length of threads specified in all tables shall be measured to include the countersink or chamfer. 7.5 Alignment The maximum allowable variation in the alignment of threads of all openings of threaded fittings shall be 5.0 mm/m (0.06 in./ft)(0.5% slope).6 DIMENSIONS AND TOLERANCES 6.1 General The tolerances in Tables 2 and I-2 are for center-to-end dimensions of the fittings. Center-to-end dimensions in millimeters are given for both straight and reducing fittings in Tables 3 through 18 (Tables I-3 through I-18 are in U.S. Customary units). The sketches of fittings shown in this Standard are representative and for the purpose of illustration. 6.2 Reducing Fittings The dimensions in Tables 3 through 18 (Tables I-3 through I-18) of reducing fittings are for use only when making patterns for the specific reducing fitting in ques- tion and do not apply when a larger size pattern is bushed to make the reducing fitting wanted. 6.3 Tolerances It is recognized that some variations are absolutely unavoidable in the making of patterns and castings. The following tolerances shall apply.