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ASME B31.3-2016 <br /> Table 304.1.1 Values of Coefficient Y fort< D16 <br /> Temperature, °C( F) <br /> 482 (900) 510 538 566 593 621 649 677 (1,250) <br /> Material and Below (950) (1,000) (1,050) (1,100) (1,150) (1,200) and Above <br /> Ferritic steels 0.4 0.5 0.7 0.7 0.7 0.7 0.7 0.7 <br /> Austenitic steels 0.4 0.4 0.4 0.4 0.5 0.7 0.7 0.7 <br /> Nickel alloys 0.4 0.4 0.4 0.4 0.4 0.4 0.5 0.7 <br /> UNS Nos. N06617, <br /> N08800, N08810, <br /> and N08825 <br /> Gray iron 0.0 ... ... ... ... ... ... ... <br /> Other ductile metals 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4 <br /> Fig. 304.2.1 Nomenclature for Pipe Bends Fig. 304.2.3 Nomenclature for Miter Bends <br /> ---- <br /> � I <br /> 7 / <br /> Intrados I 1 / <br /> i <br /> Extrados r2 <br /> a <br /> 304.2 Curved and Mitered Segments of Pipe T g <br /> M-�304.2.1 Pipe Bends. The minimum required thick- <br /> ness, t,,,, of a bend, after bending, in its finished form, <br /> shall be determined in accordance with eqs. (2)and (3c) Rt <br /> PD �D� <br /> t _ 2[(SEW/I) +PY] (3c) <br /> where at the intrados (inside bend radius) 304.2.2 Elbows. Manufactured elbows not in accor- <br /> dance with para. 303 shall be qualified as required by <br /> I <br /> _ 4(Ri/D) - 1 (3d) para. 304.7.2 or designed in accordance with <br /> 4(Ri/D) 2 para. 304.2.1, except as provided in para. 328.4.2(b)(6). <br /> and at the extrados (outside bend radius) 304.2.3 Miter Bends. An angular offset of 3 deg or <br /> _ 4(Ri/D) + 1 less (angle a in Fig. 304.2.3) does not require design <br /> I 4(Ri/D) +2 (3e) consideration as a miter bend. Acceptable methods for <br /> pressure design of multiple and single miter bends are <br /> and at the sidewall on the bend centerline radius, given in (a) and (b) below. <br /> I = 1.0, and where (a) Multiple Miter Bends. The maximum allowable <br /> Ri = bend radius of welding elbow or pipe bend internal pressure shall be the lesser value calculated from <br /> eqs. (4a) and (4b). These equations are not applicable <br /> Thickness variations from the intrados to the extrados when 0 exceeds 22.5 deg. <br /> and along the length of the bend shall be gradual. The <br /> thickness requirements apply at the mid-span of the P. _ SEW T-c T-c (4a) <br /> bend,y/2,at the intrados,extrados,and bend centerline r2 ((T-c) +0.643 tang r2(T-0) <br /> radius.The minimum thickness at the end tangents shall <br /> not be less than the requirements of para. 304.1 for I _ SEW(T-c) Ri -r2 (4b) <br /> straight pipe (see Fig. 304.2.1). r2 (R, -0.5r2) <br />