ASME B16.3-2016 pdf download
ASME B16.3-2016 pdf download.Malleable Iron Threaded Fittings.
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 of identi- fying the end connection of fittings. The number is not necessarily 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 Fig. 1 illustrate how the reduc- ing fittings are read. 5 MARKING 5.1 Class 150 Fittings Each Class 150 fitting shall be marked for identifica- tion with the manufacturer’s name or trademark. 5.2 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 6 MATERIAL 6.1 Malleable Iron The chemical and physical properties of the castings shall be in accordance with ASTM A197. The manufac- turer shall be prepared to certify that the product has been so produced. 6.2 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.
7.2.2 The transition in wall thickness from one end size to another shall be in a manner that minimizes the additionofstress caused by sudden changes in direc- tion or wall thickness. 7.2.3 Proof of design shall be verified by a hydro- static pressure test made at ambient temperature in which pressure is applied for a continuous period of no less than 1 min and at a constant minimum pressure of no less than 5 times the pressure rating of the largest size of end connection in the reducing fitting. Testing is considered successful only when no evidence of crack- ing, fracturing, or leakage is exhibited after holding for at least the minimum time at or above the required pressure. 7.3 Tolerances 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. Metal thickness at no point in the castings shall be less than 90% of the value given in the tables. (b) Center-to-End Tolerances. Permitted tolerances on the center-to-end dimensions of the fittings are shown inTables 2 and I-2. 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 tolerances do not apply to return bends and caps. 8 THREADING 8.1 Types of Threads All fittings shall be threaded according to ANSI/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. 8.2 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).
