MANDATORY APPENDIX 32 LOCAL THIN AREAS IN CYLINDRICAL SHELLS AND IN SPHERICAL SEGMENTS OF SHELLS

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1 ASME BPVC.Vlll MANDATORY APPENDX 32 LOCAL THN AREAS N CYLNDRCAL SHELLS AND N SPHERCAL SEGMENTS OF SHELLS 32-1 SCOPE The rules of this Appendix permit acceptable Local Thin Areas (LTAs) n cylindrical shells or spherical segments of shells (such as spherical vessel, hemispherical heads, and the spherical portion of torispherlcal and ellipsoidal heads) under internal pressure be less than the required thickness required by UG-16, UG-27, or UG-32 as applicable. Local thin areas on the nside or outside of cylindrical shells or spherical segments of shells designed for nternal pressure are acceptable, provided they meet the requirements in this Appendix GENERAL REQUREMENTS (a) The Manufacturer shall maintain records of the calculations and the location and extent of all LT As that are evaluated using this Appendix, and provide such informa tlon to the purchaser or the User or the User's designated agent f requested. This nformation shall be documented in the design calculations made to meet the requirements of this Appendix. (b) The maximum design temperature shall not exceed the maximum temperature limits specified n Table (c) This Appendix shall not be applied to Part UF vessels. (d) The provisions of this Appendix do not apply to corrosion-resistant linings or overlays. (e) All other applicable requirements of this Division shall be met 32-3 NOMENCLATURE C = projected circumferential length of LT A in a cylindrical shell, in. D = per UG 32 DL = maximum dimension of LTA in a spherical segment, in. L = projected axial length of L TA in a cylindrical shell, in. LT A = local thin area R = inside radius for cylindrical shell or spherical segment; for ellipsoidal heads R = K 0 D where K 0 s from Table UG-33.1, n. t = required thickness per UG-27(c), UG-27(d), UG 32(c), UG-32(d), or UG-32(e), as applicable, but not less than thickness requirements of UG-16, in. tl = minimum thickness of LTA, n. 8 = see Figure SNGLE LOCAL THN AREAS N CYLNDRCAL SHELLS (a) Single LTA shall satisfy the following equations: ti ~ 0.9 t.,.. 3. t - ti... - m. 16 (b) Any edge ofan LTA shall not be closer than 2.SJifi from a structural discontinuity such as a head or stiffener. (c) For openings meeting UG 36(c)(3), the minimum axial distance between the edge of the LTA and the center of the opening shall be equal to or greater than the inside diameter of the opening plus J'ift. (d) For openings not meeting UG-36(c](3), the mini mum axial distance between the edge of the L TA and the reinforcement limit of the opening shall be equal to or greater than.[rt. (e) The blend between the LTA and the thicker surface shall be with a taper length not less than three times the LTA depth as shown n Figure 32 3, sketch (b). The mini mum bottom blend radius shall be equal to or greater than two times the L TA depth as shown n Figure 32 3, sketch (b). (fl The longitudinal stresses on the LTA from mechan lcal loads other than internal pressure shall not exceed 0.3S. (g) The thickness at the L TA shall meet the require ments of UG-23(b) and/or UG 28 as applicable. (1) (2) (3) (4} 525 Copyright 2015 by the American Society or Mechanical Engineers. dlb No n:production may be made of this material without written consent of ASME. ~

2 3Z S- 3Z 6 ASME BPVC.Vlll.l ZOtS Figure 32-3 Nomenclature Circumferential direction (2) When 9 > 45 deg, both or the following shall be met: (-a) The minimum axial separation shall be equal to or greater than: 2.91cos8 (l1 + l i) 2 (al..._-h~axial direction (-b) The minimum circumrerentlal separation shall be equal to or greater than 2t. (b) Multiple pairs of LTA are acceptable, provided all pairs meet the rules or a single pair specified n (a). {c) Multiple local thin areas may be combined as a single L TA. The resultant single L TA is acceptable if it satisfies the rules or l or Cor DL ~ LTA:d ptn-- Radius ;;i:: 121 x LTA depth lb) Taper length <!!(3) x LTA depth 32-6 SNGLE LOCAL THN AREAS N SPHERCAL SEGMENTS OF SHELLS {a) The single LTA shall satisfy the following equations:!l.. <!: 0.9 t (S) Axial separation _.. 1 {6) 3 t - ti S - n. 16 (7) le:) Circumferential separation 32-5 MULTPLE LOCAL THN AREAS N CYLNDRCAL SHELLS {a) A pair or local areas with finished axial length, L 1 and L 2 [see Figure 32-3, sketch (c)j are acceptable F the ndividual LTA satisfies the requirements or 32 4 above and one or the following conditions ((1) or (2)J s met (1) When 9 s 45 deg. the minimum axial separation [see Figure 32-3, sketch (c)] shall be the greater or: ( Scos8)(l1 + lz} "'-----=-.-..;..--'=or 2 t 2 (b) For openings meeting UG-36(c)(3), the minimum distance between the edge or the LTA and the center or the opening shall be equal to or greater than the nside diameter or the opening plus./rt. {c) For openings not meeting UG 36(c)(3), the mini mum distance between the edge or the LTA and the reinforcement limit of the opening shall be equal to or greater than.[ri. (d) The edges of a LTA shall not be closer than 2.SJRi from a structural discontinuity. {e) A constant thickness junction between head and cylindrical shell is not considered to be a structural discon tlnulty for LT A rules. (fl The blend between the LTA and the thicker surface shall be with a taper length not less than three times the LT A depth. The minimum bottom blend radius shall be equal to or greater than two times the LT A depth. The blend requirements are shown n Figure 32-3, sketch (b). (g) The L TA for a torispherical head must lie entirely within the spherical portion of the head. See Figure Copyright 2015 by the American Society of MechmiCill Engineers. & No reproduction mily be made of this millerial without written consent of ASME. Gi:Si'

3 ASME BPVC.VJll Figure 32-6.l Limits for Torlspherlcal Head 32-7 MULTPLE LOCAL THN AREAS N SPHERCAL SEGMENTS OF SHELLS (a) Multiple LTAs may be combined and evaluated as a single LTA. The encompassed areas of the combined LTAs shall be within the DL dimension. (b) Each LTA in the encompassed area shall meet the rules of {c) Multiple L TAs may be treated as single L TAs provided their edges are no closer than z.sfft. (h) The LTA for an ellipsoidal head must lie entirely within a circle, the center of which coincides with the axis of the vessel and the diameter of which is equal to 80% of the shell nside diameter. See Figure (i) The L TA for a hemispherical head is acceptable within any portion of the head except as limited by (d). See Figure (j) The thickness at the L TA shall meet the requirements of UG-2B(d} or UG-33 as applicable. (k) The provisions of this Appendix do not apply to the torus portion of either a torlspherical or ellipsoidal head, to Hat heads, or to conical heads DATA REPORTS When all the requirements of this Division and supple mental requirements of this Appendix have been met, the following notation shall be entered on the Manufacturer's Data Report under Remarks: "Constructed n Confor mance With Mandatory Appendix 32, Local Thin Areas n Cylindrical Shells and n Spherical Segments of Shells." Figure Limits for Ellipsoidal Head i sdltalimlt ---.i ~ !~ D. h _J_ 527 Copyri~h t 2015 by the American Society of MccNnical Engineers. No reproduchon m;iy be made of this malcrial without wrillen consent of ASME

4 32 8 ASME BPVC.Vlll Figure Limits for Hemispherical Head i ltalimit -----~ L TA limit [see 32 6(d)J ----i r ' D i 'ii ~ J) r ' D -+ l Constant Thickness Junction (bl Nonconstent Thickness Junction 528 Copyright 2015 by the American Society of Mechanical Eng~rs. &P.i No reproduction!ny be mllde of this material without written consent of ASME ~

5 Page 5 of 6 nsert A 32-4 Allowable Locations for Local Thin Areas (a) For openings meeting UG-36(c)(3), the minimum distance between the edge of the LTA and the center of the opening shall be equal to or greater than the inside diameter of the opening plus Rt. (b) For openings not meeting UG-36(c)(3), the minimum distance between the edge of the LTA and the reinforcement limit of the opening shall be equal to or greater than Rt. (c) For tori-spherical and ellipsoidal heads, the edge of a LTA shall not be closer than 2.5 Rt to the cylindrical shell side of the tangent line of the head to cylinder junction. (d) A LTA is not acceptable within the torus portion of a tori-spherical, or an ellipsoidal head. (e) The LTA for a tori-spherical head must lie entirely within the spherical portion of the head. See Figure (f) The LTA for an ellipsoidal head must lie entirely within a circle, the center of which coincides with the axis of the vessel and the diameter of which is equal to 80% of the shell inside diameter. See Figure (g) A constant thickness head to cylinder junction for a hemispherical heads is not considered an area of high stress for LTA rules. The LTA for a hemispherical head is acceptable within the entire head and shell region for a constant thickness hemispherical head to cylinder junction as shown in Figure (a). The location for an LTA is limited for a non-constant thickness hemispherical head to cylinder junction as shown in Figure (b). For both constant thickness and non-constant thickness hemispherical head to cylinder junctions LTAs are limited by (a), (b), and (h). (h) The edge of a LTA shall not be closer than 2.5 Rt to the centerline of a stiffing ring or structural support. (i) A junction between two sections of the same thickness within a cylindrical shell, hemispherical head, tori-spherical head, or ellipsoidal head, is not considered an area of high stress for LTA rules and does not limit the allowable location of an LTA. (j) A LTA is not acceptable within a flat heads, or a conical heads. Figure Limits for Torispherical Head

6 Page 6 of 6 Figure Limits for Ellipsoidal Head (a)constant Thickness Junction (b) Non constant Thickness Junction Figure Limits for Hemispherical Head 32 5 Blend Grinding Requirements for an LTA (a)the blend between the LTA and the thicker surface shall be with a taper length not less than three times the LTA depth as shown n Figure (b). The minimum bottom blend radius shall be equal to or greater than two times the LTA depth as shown in Figure L,C,or D L Figure LTA Blend Grinding