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ASME B31.3-2016 <br /> (e) Multiple Branches. When two or more branch con- hx = height of the extruded outlet. This must be <br /> nections are so closely spaced that their reinforcement equal to or greater than rx [except as shown in <br /> zones overlap,the distance between centers of the open- sketch (b) in Fig. 304.3.4]. <br /> ings should be at least Q2 times their average diameter, L5 = height of reinforcement zone <br /> and the area of reinforcement between any two openings = 0.7 DbTx <br /> shall be not less than 50% of the total that both require. rx = radius of curvature of external contoured por- <br /> Each opening shall have adequate reinforcement in tion of outlet,measured in the plane containing <br /> accordance with paras.304.3.3(b)and(c).No part of the the axes of the header and branch <br /> metal cross section may apply to more than one opening Tx = corroded finished thickness of extruded outlet, <br /> or be evaluated more than once in any combined area. measured at a height equal to rx above the out- <br /> (Consult PFI Standard ES-7, Minimum Length and side surface of the header <br /> Spacing for Branch Connections,for detailed recommen- <br /> dations on spacing of welded nozzles.) (d) Limitations on Radius rx. The external contour <br /> (f) Added Reinforcement radius, rx,is subject to the following limitations: <br /> (1) Reinforcement added in the form of a ring or (1) minimum rx — the lesser of 0.05Db or 38 mm <br /> saddle as part of area A4 shall be of reasonably constant (1.50 in.) <br /> width. (2) maximum rx shall not exceed <br /> (2) Material used for reinforcement may differ from (a) for Db < DN 200 (NPS 8), 32 mm (1.25 in.) <br /> that of the run pipe provided it is compatible with run (b) for Db >- DN 200, 0.1Db + 13 mm (0.50 in.) <br /> and branch pipes with respect to weldability,heat treat- (3) for an external contour with multiple radii,the <br /> ment requirements, galvanic corrosion, thermal expan- requirements of(1)and (2)above apply,considering the <br /> sion, etc. best-fit radius over a 45 deg arc as the maximum radius <br /> (3) If the allowable stress for the reinforcement (4) machining shall not be employed in order to <br /> material is less than that for the run its calculated meet the above requirements <br /> pipe, ( <br /> area must be reduced in the ratio of allowable stress e) Required Reinforcement Area. The required area of <br /> values in determining its contribution to area A4. reinforcement is defined by <br /> (4) No additional credit maybe taken for a material A Kt d (9) <br /> 1 = h x <br /> having higher allowable stress value than the run pipe. <br /> where K is determined as follows: <br /> 304.3.4 Reinforcement of Extruded Outlet Headers (1) For Db/Dh > 0.60, K = 1.00. <br /> (a) The principles of reinforcement stated in (2) For 0.60>-Db/Dh>0.15,K = 0.6+%3(Db/Dh). <br /> para.304.3.3 are essentially applicable to extruded outlet (3) For Db/Dh <- 0.15, K = 0.70. <br /> headers. An extruded outlet header is a length of pipe <br /> in which one or more outlets for branch connection have (f) Available Area. The area available for reinforcement <br /> is defined as <br /> been formed by extrusion,using a die or dies to control <br /> the radii of the extrusion. The extruded outlet projects Az +A3 +A4>-Ai (9a) <br /> above the surface of the header a distance hx at least <br /> equal to the external radius of the outlet rx (i.e.,hx>-rx). These areas are all within the reinforcement zone and <br /> (b) The rules in para. 304.3.4 are minimum require- are further defined below. <br /> ments,valid only within the limits of geometry shown (1) Area Az is the area resulting from excess thick- <br /> in Fig. 304.3.4, and only where the axis of the outlet ness in the header wall <br /> intersects and is perpendicular to the axis of the header. <br /> Where these requirements are not met,or where noninte- Az = (2dz -dx)(Th-th-c) (10) <br /> gral material such as a ring, pad, or saddle has been <br /> (2) Area A3 is the area resulting from excess thick- <br /> added to the outlet, pressure design shall be qualified ness in the branch pipe wall <br /> as required by para. 304.7.2. <br /> (c) Nomenclature. The nomenclature used herein is A3 = 2L5(Tb-tb-c) (11) <br /> illustrated in Fig. 304.3.4. Note the use of subscript x <br /> signifying extruded.Refer to para.304.3.3(a)for nomen- (3) Area A4 is the area resulting from excess thick- <br /> clature not listed here. ness in the extruded outlet lip <br /> dx = the design inside diameter of the extruded out- A4 = 2rx[Tx- (Tb-c)] (12) <br /> let,measured at the level of the outside surface <br /> of the header. This dimension is taken after (g) Reinforcement of Multiple Openings. The rules of <br /> removal of all mechanical and corrosion allow- para. 304.3.3(e) shall be followed, except that the <br /> ances, and all thickness tolerances. required area and reinforcement area shall be as given <br /> d2 = half width of reinforcement zone (equal to dx) in para. 304.3.4. <br />