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ASME B31.3-2016 <br /> (b) Single Miter Bends 304.2.4 Curved and Mitered Segments of Pipe Under <br /> (1) The maximum allowable internal pressure for External Pressure. The wall thickness of curved and <br /> a single miter bend with angle 0 not greater than 22.5 deg mitered segments of pipe subjected to external pressure <br /> shall be calculated by eq. (4a). may be determined as specified for straight pipe in <br /> (2) The maximum allowable internal pressure for para. 304.1.3. <br /> a single miter bend with angle 0 greater than 22.5 deg <br /> shall be calculated by eq. (4c) 304.3 Branch Connections <br /> SEW(T-c T-c 304.3.1 General <br /> Pm = r (4c) (a) Except as provided in(b)below,the requirements <br /> �(T-c) + 1.25 tang r2(T-c)) <br /> in paras.304.3.2 through 304.3.4 are applicable to branch <br /> (c) The miter pipe wall thickness,T,used in eqs. (4a), connections made in accordance with the following <br /> (4b), and (4c) shall extend a distance not less than M methods: <br /> from the inside crotch of the end miter welds where (1) fittings(tees,extruded outlets,branch outlet fit- <br /> M = the larger of 2.5(r2T)0.5 or tan 0(R1 - r2) tings in accordance with MSS SP-97,laterals, crosses) <br /> (2) unlisted cast or forged branch connection fit- <br /> The length of taper at the end of the miter pipe may be tings (see para. 300.2), and couplings not over DN 80 <br /> included in the distance,M. (NPS 3), attached to the run pipe by welding <br /> (d) The following nomenclature is used in eqs. (4a), (3) welding the branch pipe directly to the run pipe, <br /> (4b), and (4c) for the pressure design of miter bends: with or without added reinforcement, as covered in <br /> c = same as defined in para. 304.1.1 para. 328.5.4 <br /> E = same as defined in para. 304.1.1 (b) The rules in paras.304.3.2 through 304.3.4 are min- <br /> P, = maximum allowable internal pressure for imum requirements, valid only for branch connections <br /> miter bends in which (using the nomenclature of Fig. 304.3.3) <br /> Ri = effective radius of miter bend, defined as the (1) the run pipe diameter-to-thickness ratio(Dh/Th) <br /> shortest distance from the pipe centerline to is less than 100 and the branch-to-run diameter ratio <br /> the intersection of the planes of adjacent (Db/Dh) is not greater than 1.0 <br /> miter joints (2) for run pipe with Dh/Th>-100,the branch diame- <br /> r2 = mean radius of pipe using nominal wall T ter, Db, is less than one-half the run diameter, Dh <br /> S = same as defined in para. 304.1.1 (3) angle 6 is at least 45 deg <br /> T = miter pipe wall thickness (measured or mini- (4) the axis of the branch intersects the axis of <br /> mum in accordance with the purchase the run <br /> specification) (c) Where the provisions of(a) and (b) above are not <br /> W = same as defined in para. 304.1.1 met, pressure design shall be qualified as required by <br /> a = angle of change in direction at miter joint para. 304.7.2. <br /> = 20 (d) Other design considerations relating to branch <br /> 0 = angle of miter cut connections are stated in para. 304.3.5. <br /> For compliance with this Code, the value of R1 shall 304.3.2 Strength of Branch Connections. A pipe (16) <br /> be not less than that given by eq. (5) having a branch connection is weakened by the opening <br /> that must be made in it and, unless the wall thickness <br /> _ A D of the pipe is sufficiently in excess of that required to <br /> Ri tan B+ 2 (5) sustain the pressure, it is necessary to provide added <br /> reinforcement.The amount of reinforcement required to <br /> where A has the following empirical values: sustain the pressure shall be determined in accordance <br /> (1) For SI metric units with para.304.3.3 or 304.3.4.There are,however,certain <br /> branch connections that have adequate pressure <br /> (T-c),mm A strength or reinforcement as constructed. It may be <br /> <13 25 assumed without calculation that a branch connection <br /> 13<(T-c)<22 2(T-c) has adequate strength to sustain the internal and exter- <br /> >>22 [2(T-c)13]+30 nal pressure that will be applied to it if <br /> (2) For U.S. Customary units (a) the branch connection is made with a listed branch <br /> type fitting such as an ASME 1316.9 or ASME 1316.11 tee, <br /> (T-c),in. A or MSS SP-97 branch connection fitting. See para. 303. <br /> <0.5 1.0 (b) the branch connection is made by welding a listed <br /> 0.5<(T-c)<0.88 2(T-c) threaded or socket welding coupling or listed half cou- <br /> >>0.88 [2(T-c)/3]+1.17 pling directly to the run in accordance with para.328.5.4, <br />