2007 asme boilder and pressure vessel code asme section viii d2

```,,,,,,``,`,``,,`````,`,`,``-`-`,,`,,`,`,,` - Copyright ASME International Provided by IHS under license with ASME No reproduction or networking permitted without license from IHS Licensee=Chevron Corp/5912388100 Not for Resale, 08/28/2008 13:31:07 MDT A N I N T E R N AT I O N A L CO D E 2007 ASME Boiler & Pressure Vessel Code 2008a Addenda July 1, 2008 VIII Division Alternative Rules RULES FOR CONSTRUCTION OF PRESSURE VESSELS ASME Boiler and Pressure Vessel Committee Subcommittee on Pressure Vessels ```,,,,,,``,`,``,,`````,`,`,``-`-`,,`,,`,`,,` - Copyright ASME International Provided by IHS under license with ASME No reproduction or networking permitted without license from IHS Licensee=Chevron Corp/5912388100 Not for Resale, 08/28/2008 13:31:07 MDT U082W8 Date of Issuance: July 1, 2008 This international code or standard was developed under procedures accredited as meeting the criteria for American National Standards and it is an American National Standard The Standards Committee that approved the code or standard was balanced to assure that individuals from competent and concerned interests have had an opportunity to participate The proposed code or standard was made available for public review and comment that provides an opportunity for additional public input from industry, academia, regulatory agencies, and the public-at-large ASME does not “approve,” “rate,” or “endorse” any item, construction, proprietary device, or activity ASME does not take any position with respect to the validity of any patent rights asserted in connection with any items mentioned in this document, and does not undertake to insure anyone utilizing a standard against liability for infringement of any applicable letters patent, nor assume any such liability Users of a code or standard are expressly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, is entirely their own responsibility Participation by federal agency representative(s) or person(s) affiliated with industry is not to be interpreted as government or industry endorsement of this code or standard ASME accepts responsibility for only those interpretations of this document issued in accordance with the established ASME procedures and policies, which precludes the issuance of interpretations by individuals The footnotes in this document are part of this American National Standard No part of this document may be reproduced in any form, in an electronic retrieval system or otherwise, without the prior written permission of the publisher Library of Congress Catalog Card Number: 56-3934 Printed in the United States of America The American Society of Mechanical Engineers Three Park Avenue, New York, NY 10016-5990 Copyright © 2008 by THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS All rights reserved ```,,,,,,``,`,``,,`````,`,`,``-`-`,,`,,`,`,,` - Copyright ASME International Provided by IHS under license with ASME No reproduction or networking permitted without license from IHS Licensee=Chevron Corp/5912388100 Not for Resale, 08/28/2008 13:31:07 MDT A N I N T E R N AT I O N A L CO D E 2007 ASME Boiler & Pressure Vessel Code 2007 Edition July 1, 2007 ```,,,,,,``,`,``,,`````,`,`,``-`-`,,`,,`,`,,` - VIII Division Alternative Rules RULES FOR CONSTRUCTION OF PRESSURE VESSELS ASME Boiler and Pressure Vessel Committee Subcommittee on Pressure Vessels Copyright ASME International Provided by IHS under license with ASME No reproduction or networking permitted without license from IHS Licensee=Chevron Corp/5912388100 Not for Resale, 08/28/2008 13:31:07 MDT Date of Issuance: July 1, 2007 This international code or standard was developed under procedures accredited as meeting the criteria for American National Standards and it is an American National Standard The Standards Committee that approved the code or standard was balanced to assure that individuals from competent and concerned interests have had an opportunity to participate The proposed code or standard was made available for public review and comment that provides an opportunity for additional public input from industry, academia, regulatory agencies, and the public-at-large ASME does not “approve,” “rate,” or “endorse” any item, construction, proprietary device, or activity ASME does not take any position with respect to the validity of any patent rights asserted in connection with any items mentioned in this document, and does not undertake to insure anyone utilizing a standard against liability for infringement of any applicable letters patent, nor assume any such liability Users of a code or standard are expressly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, is entirely their own responsibility Participation by federal agency representative(s) or person(s) affiliated with industry is not to be interpreted as government or industry endorsement of this code or standard ASME accepts responsibility for only those interpretations of this document issued in accordance with the established ASME procedures and policies, which precludes the issuance of interpretations by individuals The footnotes in this document are part of this American National Standard ASME collective membership mark The above ASME symbols are registered in the U.S Patent Office “ASME” is the trademark of the American Society of Mechanical Engineers No part of this document may be reproduced in any form, in an electronic retrieval system or otherwise, without the prior written permission of the publisher Library of Congress Catalog Card Number: 56-3934 Printed in the United States of America Adopted by the Council of the American Society of Mechanical Engineers, 1914 Revised 1940, 1941, 1943, 1946, 1949, 1952, 1953, 1956, 1959, 1962, 1965, 1968, 1971, 1974, 1977, 1980, 1983, 1986, 1989, 1992, 1995, 1998, 2001, 2004, 2007 The American Society of Mechanical Engineers Three Park Avenue, New York, NY 10016-5990 Copyright © 2007 by THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS All Rights Reserved ```,,,,,,``,`,``,,`````,`,`,``-`-`,,`,,`,`,,` - Copyright ASME International Provided by IHS under license with ASME No reproduction or networking permitted without license from IHS Licensee=Chevron Corp/5912388100 Not for Resale, 08/28/2008 13:31:07 MDT SUMMARY OF CHANGES Addenda to the 2007 Edition of the Code are issued in the form of replacement pages Revisions, additions, or deletions are incorporated directly into the affected pages It is advisable, however, that all replaced pages be retained for reference Replace or insert the pages listed Changes given below are identified on the pages by a vertical line placed next to the affected area For the listing below, the Page references the affected area A vertical line placed next to the heading indicates Location Revisions are listed under Change Record Numbers listed below are explained in more detail in “List of Changes in Record Number Order” following the Summary of Changes ```,,,,,,``,`,``,,`````,`,`,``-`-`,,`,,`,`,,` - Page xxiii–xxxiii 1-3 1-4 1-8 1-8 1-13 1-14 Location Roster 1.2.1.2.b 1.2.4.1 Table 1.1 Table 1.1 1.B.2.7 1.B.2.13 1-14 2-4 2-4 1.B.2.14 2.2.2.1.d).1 2.2.2.1(f) 2-5 2.2.2.1.g.3 2-7 2.3.5 2-8 2-17 2-17 2-17 2.4.2 2.C.3 2.C.3.1.d.7 2.C.3.2 3-1 3-8 3-8 Parts Contents 3.2.9.1 3.2.9.1.b.5 3-15 3.7.4 3-25 3-32 3-34 3-39 3.11.2.4.b 3.11.7.1.b 3.11.8.1 Table 3.4 3-53 Notes for Figures 3.3, 3.3M, 3.4, and 3.4M Figure 3.6 and 3.6M 3-55 Change (Record Number) Updated to reflect 2008 Addenda Removed word Local (07-255) Removed word Local (07-255) Adopt SNT-TC-1A-2006 and CP-189-2006 (07-1679) Include ASME PCC-1 (07-301) Removed word Local (07-255) Added definition of "Specified Design Pressure" (07246) Paragraph renumbered (07-246) Added reference to paragraph 4.1.5.2.a) (07-246) Revised paragraph to require the user to evaluate design conditions of 5.5.2.2 (a) through (f) (07-285) Revised paragraph by adding consideration of filler material by user (07-318) Revised paragraph to require Manufacturer to maintain records for a duration per Annex 2C (06-1202) Remove ‘ (07-1572) Renumbered paragraphs (06-1202) Revise paragraph (08-79) Revised paragraph 2.C.3 to add new requirement for maintaining radiographic films (06-1202) Page Number Change Revised paragraph (03-1231) Added definition of Round, Hexagonal and Octagonal Solid Forgings (03-1231) Revised Paragraph to provided more specific guidance on the use of washers (07-301) Add material SA-723 (06-198) Correct paragraph reference (07-1252) Correct table reference (08-11) Correct Low Alloy Bolting diameter for SA-193 B7 (07579) Update notes regarding the impact test requirements for SA-723 (06-198) Revised Figures to incorporate new toughness requirement for materials having UTS > 95 ksi (07303) (c) Copyright ASME International Provided by IHS under license with ASME No reproduction or networking permitted without license from IHS Licensee=Chevron Corp/5912388100 Not for Resale, 08/28/2008 13:31:07 MDT Page 3-60 Location Material Assignment Table for Figures 3.7, 3.7M, 3.8, 3.8M 3-65 3-76 Figure 3.12M Table 3.A.1 3-98 Equation 3.D.1 3-99 Equation 3.D.15 3-100 Equation 3.D.16- 3.D.19 3-101 Nomenclature 4-2 4-7 4-8 Part Contents 4.1.5.2.a 4.1.5.2.b 4-48 4-54 4-55 4-55 4.3.2.2.a Equation 4.3.36 Equation 4.3.40 Equation 4.3.43 4-55 4-57 4-87 4-87 4-89 4-115 4-115 Equation 4.3.44 4.3.11.5.f Equation 4.4.39 Equation 4.4.41 Equation 4.4.50 Equation 4.5.4 Equation 4.5.10 4-115 4-116 Equation 4.5.19 Equation 4.5.20 4-116 Equation 4.5.21 4-116 Equation 4.5.28 4-116 4-117 4.5.5.1.f 4.5.5.1.j 4-119 4-119 4.5.9.1 4.5.9.2 ```,,,,,,``,`,``,,`````,`,`,``-`-`,,`,,`,`,,` - Copyright ASME International Provided by IHS under license with ASME No reproduction or networking permitted without license from IHS Change (Record Number) Revised table for materials SA-182 Gr 21 and Gr 22 to Gr F21 and F22 to correct the grade designations in Note a) For Materials SA-336 and SA-387 Added “liquid quenched and tempered” in Notes c) and d) for Revised Note h) to clarify the intent of this note to prevent the same material to also be considered as Curve C material (07-1334) Correct punctuation on x axis Correct UNS number for material specification SA-738 (08-11) Replace the variable "epsilon sub ts" with "epsilon sub t" (08-109) Replace the variable partial derivative of "sigma" with partial derivative of "sigma sub t" (08-109) Replace the variable "sigma" with "sigma sub t" (08109) Add the variable "epsilon sub t" and define as "total true strain" Replace the definitions of "epsilon sub ta" and "epsilon sub tr" with "total true strain amplitude" and "total true strain range", respectively Delete the definition of "sigma" (08-109) Pages renumbered Modified definition of design pressure (07-246) Inserted the word specified Modified definition of design pressure (07-246) Added formed head knuckle radius tolerance (07-1368) Move COS θ inside outer bracket in numerator (08-11) Remove subscript i from D in denominator (08-11) Revised to be preceded by a negative sign (07-1990) Remove the joint efficiency factor, E (07-1990) Correct reference to 4.4.12.2.h (08-11) Correct constant to 0.063 (08-11) Correct constant to 5.33 (08-11) Correct equation for α (08-11) Revised equation for Lr1 (07-1991) Insert equation for LH2 for nozzle abutting the vessel wall and renumbered subsequent equations (07-1991) Revise equation for λ (07-1991) Clarify limits of applicability for variable thickness openings (07-1991) Clarify limits of applicability for variable thickness openings and uniform thickness openings (07-1991) Insert equation for a5b for nozzle abutting the vessel wall and renumbered subsequent equations (07-1991) Insert word shell (07-1991) Revise equation references and remove definition of allowable stress for vessels under external pressure (07-1991) Revise paragraph reference to 4.5.8 (07-1991) Revise paragraph reference to 4.5.8 (07-1991) (d) Licensee=Chevron Corp/5912388100 Not for Resale, 08/28/2008 13:31:07 MDT ```,,,,,,``,`,``,,`````,`,`,``-`-`,,`,,`,`,,` - Page 4-120 Location Equation 4.5.73 and 4.5.74 4-121 4-121, 4-122 4-121 4.5.10.1.c 4.5.10.1.e Equation 4.5.85 4-121 Equation 4.5.86 4-122 Equation 4.5.93 4-123 4-125 4-127 4-128 4-128 4-129 4-135 4.5.10.1.j 4.5.12.1.d 4.5.14.2.d 4.5.14.3.b.1 4.5.14.3.b.2 4.5.14.3.b.3 Figure 4.5.1 4-136 4-312, 4-313 Figure 4.5.2 Table 4.16.1 5-3 5.1.1.2 5-8 5.2.3.2.b 5-15 5.5.2.2 5-56 5.A.1 5-57 5.A.3.c 6-5 6-7 6-9 6.1.2.5.c 6.1.3.1.d.1 6.1.6.2 6-10 6-15 6-17 6-18 6.2.2.2 6.2.5.8 6.4.2.2.e.8 6.4.3.1 6-19 6-19 6-21 6-22 6-26 6-32 6.4.3.5 6.4.3.6 6.4.5.2.f.3 6.4.6.2 6.6.5.4.b.1 6.7.7.2.c Change (Record Number) Replace equation for Lh with separate equations, one for nozzles inserted through the vessel wall and one for nozzles abutting the vessel wall and renumber subsequent equations (07-1991) Revise equation references (07-1991) Revise equation references (07-1991) Clarify limits of applicability for variable thickness openings (07-1991) Clarify limits of applicability for variable thickness openings and uniform thickness openings (07-1991) Insert equation for a5b for nozzles abutting the vessel wall and renumber subsequent equations (07-1991) Revise equation references (07-1991) Revise equation references (07-1991) Revise equation references (07-1991) Revise equation references (07-1991) Revise equation references (07-1991) Revise equation references (07-1991) Add tw1 and tw2, remove equations for variable definitions (07-1991) Add tw1 (07-1991) Replace the term "asbestos" with "mineral fiber" (071030) Delete Paragraph 5.1.1.2.a.and renumber paragraphs (08-109) Added an example of a commonly used component, i.e pipe elbow, which can experience a loss of stiffness due to deformation depending on the loading condition (07-284) Revised paragraph to indicate fatigue exemption is addressed in the Users Design Specification (07-285) deleted the incorrect reference to Appendix B1 (071709) deleted the incorrect reference to Appendix B1 (071709) Correct reference to Table 6.3 (08-79) Correct word Detail (08-79) Deleted word shall (08-79) Corrected reference to QW-201 (08-79) Remove phrase owner user or agent (07-318) Add P-No 10C Group (08-79) Add reference to WRC Bulletin 452, "Recommended Practices for Local Heating of Welds in Pressure Vessels" (07-344) Add word provided (08-79) Replace word this with the (08-79) Replace word assure with ensure (08-79) Correct reference to inch (08-79) Correct spacing (08-79) Remove words types of (07-354) (e) Copyright ASME International Provided by IHS under license with ASME No reproduction or networking permitted without license from IHS Licensee=Chevron Corp/5912388100 Not for Resale, 08/28/2008 13:31:07 MDT ```,,,,,,``,`,``,,`````,`,`,``-`-`,,`,,`,`,,` - Page 6-33 Location 6.7.8.5 6-33 6-33 6-35 6-43 6-46 - 6-61 6.7.9.2 6.7.10.1.a 6.8.4.2.b Table 6.5 Tables 6.8 - 6.15 6-59 Table 6.15 6-62 6-63 6-71 7-1,7-2 7-4 Table 6.16 Table 6.17 Figure 6.6 Part Contents 7.3.6 7-12 7-12 7-13 7.5.3.1.a 7.5.3.1.b 7.5.3.2.a.3 7-13 7.5.3.2.b.1.i 7-14 7-16 7-16 7-18 7-19 7-19 7-22 7-24 7-25 - 7-27 7.5.4.1.b 7.5.5.1.g 7.5.5.1.j.3 7.5.6.1.b 7.5.7.1.b 7.5.8.1.b 7.5.9.b Table 7.1 Table 7.2 7-45 Figure 7.11 7-51 7-53,7-54 7.A.3.1.a.1 Table7.A.1 Change (Record Number) Revised paragraph to allow the provisions of 6.7.8.4 for repairs to defects in welds in forgings with a carbon content exceeding 0.35% (07-357) Correct reference to NPS (08-79) Replace word manufacture with manufacturing (08-79) Delete 0.875 replace with 7/8 (08-79) Delete extra line (08-79) Corrections to cooling rates, thicknesses, paragraph references (08-79) Added PWHT requirements for P-No 10C Group materials (08-297) Corrections to format (08-79) Corrections to title and cooling rate (08-79) Correct dimensioning for df (08-79) Added paragraph 7.3.6 Add paragraph on qualification of NDE personnel (051376) Correct reference to paragraph 2.3.5 (06-1202) Revise to be consistent with paragraph 7.3.6 (05-1376) new subparagraph iii) to address acceptance criteria for aligned linear indications (08-259) Revised to complete the definition of rounded indications (08-269) Revise to be consistent with paragraph 7.3.6 (05-1376) Revise to be consistent with paragraph 7.3.6 (05-1376) Revise to be consistent with paragraph 7.3.6 (05-1376) Revise to be consistent with paragraph 7.3.6 (05-1376) Revise to be consistent with paragraph 7.3.6 (05-1376) Revise to be consistent with paragraph 7.3.6 (05-1376) Revised paragraph 7.5.9(b) for greater clarity (07-372) Correct reference to Annex 3.A (08-79) Revised for improved clarity, appearance and readability Added joint types under Categories C, D and E (06-1204) Revised signs in Figure 7.11 sketches (b) and (c) to be consistent with Code Case 2235-9 (07-205) Revised paragraph to remove redundancy (06-1207) Revise to be consistent with paragraph 7.3.6 (05-1376) NOTE: Volume 58 of the Interpretations to Section VIII, Division 2, of the ASME Boiler and Pressure Vessel Code follows the last page of this Addenda (f) Copyright ASME International Provided by IHS under license with ASME No reproduction or networking permitted without license from IHS Licensee=Chevron Corp/5912388100 Not for Resale, 08/28/2008 13:31:07 MDT LIST OF CHANGES IN RECORD NUMBER ORDER Record Number 03-1231 05-1376 06-198 06-1202 06-1204 Change Revised paragraph 3.2.9.1 Added to paragraph 3.2.9.1.b.5 definition of Round, Hexagonal and Octagonal Solid Forgings Added new paragraph 7.3.6 on qualification of NDE personnel Revised paragraphs 7.5.3.1, 7.5.4.1, 7.5.5.1, 7.5.6.1, 7.5.7.1, 7.5.8.1, and Table 7.A.1 to be consistent with new paragraph 7.3.6 Revised paragraph 3.11.2.4.b to add SA-723 Revised Notes for Figure 3.3, Figure 3.3M, Figure 3.4, and Figure 3.4M regarding the impact test requirements for SA-723 Revised paragraph 7.5.3.1a to refer user to paragraph 2.3.5 Revised paragraph 2.3.5 to require Manufacturer to maintain records for a duration per Annex 2C Revised paragraph 2.C.3 to add new requirement for maintaining radiographic films Revised Table 7.2 for improved clarity, appearance and readability Added joint types under Categories C, D and E 06-1207 07-205 Revised paragraph 7.A.3.1.a.1 Revised signs in Figure 7.11 sketches (b) and (c) to be consistent with Code Case 2235-9 07-246 Paragraph 1.B.2.13 added definition of "Specified Design Pressure" Renumbered paragraph 1.B.2.14 Paragraph 2.2.2.1.d).1) Added reference to paragraph 4.1.5.2.a) Paragraph 4.1.5.2.a) Modified definition of design pressure 07-255 Revised Paragraph 1.2.1.2 b), 1.2.4.1 and Annex 1B by removing the word "local" from "Local Jurisdictional Authority" Added an example, in paragraph 5.2.3.2(b), of a commonly used component, i.e pipe elbow, which can experience a loss of stiffness due to deformation depending on the loading condition 07-284 07-285 Revised paragraph 5.5.2.2 to indicate fatigue exemption is addressed in the Users Design Specification Revised paragraph 2.2.2.1(f) to require the user to evaluate design conditions of 5.5.2.2 (a) through (f) 07-301 Revised Table 1.1 to include ASME PCC-1 Revised Paragraph 3.7.4 to provided more specific guidance on the use of washers 07-303 Revised Figure 3.6 Figure 3.6M to incorporate new toughness requirement for materials having UTS > 95 ksi ```,,,,,,``,`,``,,`````,`,`,``-`-`,,`,,`,`,,` - Copyright ASME International Provided by IHS under license with ASME No reproduction or networking permitted without license from IHS (g) Licensee=Chevron Corp/5912388100 Not for Resale, 08/28/2008 13:31:07 MDT 2007 SECTION VIII, DIVISION PART PRESSURE VESSEL OVERPRESSURE PROTECTION PART CONTENTS 9.1 9.1.1 9.1.2 9.1.3 9.1.4 9.2 9.3 9.3.1 9.3.2 9.3.3 9.4 9.4.1 9.4.2 9.4.3 9.5 9.6 9.6.1 9.6.2 9.6.3 9.6.4 9.7 9.7.1 9.7.2 9.7.3 General Requirements 9-2 Protection Against Overpressure 9-2 Types of Overpressure Protection 9-2 Required Relieving Capacity and Allowable Overpressure 9-2 Pressure Setting of Pressure Relief Devices 9-3 Pressure Relief Valves 9-3 Non-Reclosing Pressure Relief Devices .9-3 Rupture Disk Devices 9-3 Breaking Pin Devices .9-3 Spring Loaded Non-Reclosing Pressure Relief Devices .9-3 Calculation Of Rated Capacity For Different Relieving Pressures And/Or Fluids 9-3 General 9-3 Prorating of Certified Capacity for Different Pressures 9-3 Conversion of Certified Capacity for Different In-Service Fluids 9-4 Marking and Stamping 9-4 Provisions for Installation of Pressure Relieving Devices 9-4 General 9-4 Inlet Piping for Pressure Relief Devices .9-4 Discharge Lines from Pressure Relief Devices .9-4 Pressure Drop, Non-Reclosing Pressure Relief Devices .9-4 Overpressure Protection by Design 9-4 Requirements .9-4 Documentation .9-5 Manufacturer’s Data Report 9-5 ```,,,,,,``,`,``,,`````,`,`,``-`-`,,`,,`,`,,` - Annex 9.A Best Practices For The Installation And Operation Of Pressure Relief Devices 9.A.1 Introduction 9-6 9.A.2 Provisions for the Installation of Stop Valves in the Relief Path 9-6 9.A.3 Inlet Piping Pressure Drop for Pressure Relief Valves 9-9 9.A.4 Discharge Lines from Pressure Relief Devices 9-9 9.A.5 Cautions Regarding Pressure Relief Device Discharge into a Common Header .9-10 9.A.6 Pressure Differentials (Operating Margin) for Pressure Relief Valves .9-10 9.A.7 Pressure Relief Valve Orientation .9-10 9.A.8 Reaction Forces and Externally Applied Piping Loads .9-10 9.A.9 Sizing of Pressure Relief Devices for Fire Conditions 9-12 9.A.10 Use of Pressure Indicating Devices to Monitor Pressure Differential 9-12 Copyright ASME International Provided by IHS under license with ASME No reproduction or networking permitted without license from IHS 9-1 Licensee=Chevron Corp/5912388100 Not for Resale, 08/28/2008 13:31:07 MDT 2007 SECTION VIII, DIVISION 9.1 General Requirements a) This Part provides the requirements for pressure relief devices used to protect against overpressure in pressure vessels constructed to the requirements of this Division It establishes the type, quantity, and settings of acceptable devices and the relieving capacity requirements for the applicable pressure vessels Also provided are the requirements for capacity certification testing, as well as for obtaining and using the Code symbol stamp for pressure relief devices In addition, this Part provides the requirements for installation of these pressure relief devices b) Unless otherwise defined in this Division, the definitions relating to pressure relief devices in Section of ASME PTC 25 shall apply 9.1.1 Protection Against Overpressure b) The vessel Manufacturer need not supply pressure relief devices or other overpressure protection It is the responsibility of the user to ensure that the required pressure relief devices and/or overpressure protection are properly installed and in place prior to initial operation c) Pressure relief devices for vessels that are to operate completely filled with liquid shall be designed for liquid service, unless the vessel is otherwise protected against overpressure d) The protective devices provided in accordance with paragraph 9.1.1.a) need not be installed directly on a pressure vessel when the source of pressure is external to the vessel and is under such positive control that the pressure in the vessel cannot exceed the maximum allowable working pressure (MAWP) at the operating temperature except as permitted in Section VIII, Division Note that pressure reducing valves and similar mechanical or electrical control instruments, except for pilot operated pressure relief valves, are not considered as sufficiently positive in action to prevent excess pressures from being developed e) Pressure relieving devices shall be constructed, located, and installed so that they are readily accessible for testing, inspection, replacement, and repair and so that they cannot be readily rendered inoperative (see Annex 9.A for the use of stop valves), and should be selected on the basis of their intended service f) It is the responsibility of the user or his/her designated agent to size and select the pressure relief device(s) or overpressure protection provisions based on its intended service Intended service considerations shall include, but not necessarily be limited to the following: 1) Normal operating and upset conditions 2) Fluids 3) Fluid phases 9.1.2 Types of Overpressure Protection a) All pressure relief devices listed in Section VIII, Division and bearing either the "UV" or "UD" Code Symbol Stamp are permissible b) Pressure relief valves certified for a steam discharging capacity under the provisions of Section I, and bearing the official Code symbol stamp of Section I for safety valves, may be used on pressure vessels constructed to this Division The rated capacity in terms of other fluids shall be determined by the method of conversion given in Section VIII, Division 1, Appendix 11 c) Where overpressure protection is provided by means other than the use of pressure relief devices, the requirements of paragraph 9.7 shall be followed 9.1.3 a) Required Relieving Capacity and Allowable Overpressure Relieving capacity and allowable overpressure shall be in accordance with the requirements specified in Section VIII, Division Copyright ASME International Provided by IHS under license with ASME No reproduction or networking permitted without license from IHS 9-2 Licensee=Chevron Corp/5912388100 Not for Resale, 08/28/2008 13:31:07 MDT ```,,,,,,``,`,``,,`````,`,`,``-`-`,,`,,`,`,,` - a) All pressure vessels within the scope of this Division, irrespective of size or pressure, shall be provided with protection against overpressure in accordance with the requirements of this Part 2007 SECTION VIII, DIVISION b) Where overpressure protection is provided by means other than the use of pressure relief devices, the requirements of paragraph 9.7 shall be followed and the allowable overpressure (accumulation) shall not exceed the maximum allowable working pressure 9.1.4 Pressure Setting of Pressure Relief Devices All pressure relief devices shall follow all requirements of Section VIII, Division for pressure setting including tolerances 9.2 Pressure Relief Valves Except as permitted by paragraph 9.1.2.b), safety, safety relief, relief and pilot-operated pressure relief valves shall be as defined in Section VIII, Division 1, and shall meet all requirements of Section VIII, Division 9.3 9.3.1 Non-Reclosing Pressure Relief Devices Rupture Disk Devices Rupture disk devices and rupture disk holders shall be as defined in Section VIII, Division 1, and shall meet all requirements for application, burst pressure, certification and installation of Section VIII, Division 9.3.2 9.3.2.1 Breaking Pin Devices General Breaking pin devices and breaking pin housings shall be as defined in Section VIII, Division 1, and shall meet all requirements for application, break pressure and certification of flow capacity of Section VIII, Division 9.3.2.2 Determination of Rated Flow Capacity The capacity of a pressure relief valve and breaking pin combination based on an in-service fluid or inservice conditions different from those of the certification tests shall be calculated using the conversion methods provided in Section VIII, Division 1, Appendix 11 9.3.3 Spring Loaded Non-Reclosing Pressure Relief Devices Spring loaded non-reclosing pressure relief devices shall be as defined in Section VIII, Division 1, and shall meet all requirements for application, set pressure, capacity certification and tolerance of Section VIII, Division 9.4 9.4.1 Calculation Of Rated Capacity For Different Relieving Pressures And/Or Fluids General Determination of rated capacity of a pressure relief device at relieving pressures other than 110% of set pressure shall be performed in accordance with the requirements of Section VIII, Division 9.4.2 Prorating of Certified Capacity for Different Pressures Determination of the relieving capacity of a pressure relief device for in-service fluids other than steam or air shall be determined by the conversion method of Section VIII, Division 1, Appendix 11 ```,,,,,,``,`,``,,`````,`,`,``-`-`,,`,,`,`,,` - Copyright ASME International Provided by IHS under license with ASME No reproduction or networking permitted without license from IHS 9-3 Licensee=Chevron Corp/5912388100 Not for Resale, 08/28/2008 13:31:07 MDT 2007 SECTION VIII, DIVISION 9.4.3 Conversion of Certified Capacity for Different In-Service Fluids The relieving capacity of a pressure relief device for in-service fluids other than steam or air shall be determined by the method of conversion given in Section VIII, Division 1, Appendix 11 9.5 Marking and Stamping Except as permitted by paragraph 9.1.2.b), all pressure relief devices used shall be marked and stamped in accordance with the requirements of Section VIII, Division 9.6 Provisions for Installation of Pressure Relieving Devices 9.6.1 General Pressure relief device Installation shall comply with Section VIII, Division 9.6.2 Inlet Piping for Pressure Relief Devices The design of inlet piping for pressure relief devices shall be in accordance with the requirements of Section VIII, Division Additional guidance is provided in Annex 9.A 9.6.3 Discharge Lines from Pressure Relief Devices The design of discharge piping from pressure relief devices shall be in accordance with the requirements of Section VIII, Division Additional guidance is provided in Annex 9.A 9.6.4 Pressure Drop, Non-Reclosing Pressure Relief Devices Piping, valves and fittings, and vessel components comprising part of a non-reclosing device pressure relieving system shall be sized to prevent the vessel pressure from rising above the allowable overpressure 9.7 Overpressure Protection by Design 9.7.1 Requirements A pressure vessel may be provided with overpressure protection by system design in lieu of a pressure relief device or pressure relief devices under the following conditions: ```,,,,,,``,`,``,,`````,`,`,``-`-`,,`,,`,`,,` - a) The vessel is not exclusively in air, water, or steam service unless these services are critical to preventing the release of fluids that may result in safety or environmental hazards b) The decision to provide a vessel with overpressure protection by system design is the responsibility of the user The user shall specify overpressure protection by system design in writing in the purchase documents or in the User's Design Specification The Manufacturer is responsible for documenting on the Data Report that the user has specified overpressure protection by system design c) The user shall ensure that the maximum allowable working pressure of the vessel is greater than the highest pressure that can reasonably be expected to be achieved by the system The user shall conduct a detailed analysis that examines all credible scenarios that could result in an overpressure condition The "Causes of Overpressure" described in Section of API Recommended Practice 521 "Guide for Pressure-Relieving and Depressuring Systems" shall be considered An organized, systematic approach, using a multidisciplinary team, such as a Hazards and Operability Analysis (HAZOP), Failure Modes, Effects, and Criticality Analysis (FMECA), Fault Tree Analysis, Event Tree Analysis, "What-If” Analysis, or other similar methodology shall be used In all cases, the user shall determine the potential for overpressure due to all credible operating and upset conditions, including equipment and instrumentation malfunctions d) The analysis described in paragraph 9.7.1.c) shall be conducted by an engineer(s) experienced in the applicable analysis methodology Any overpressure concerns that are identified shall be evaluated by an engineer(s) experienced in pressure vessel design and analysis Copyright ASME International Provided by IHS under license with ASME No reproduction or networking permitted without license from IHS 9-4 Licensee=Chevron Corp/5912388100 Not for Resale, 08/28/2008 13:31:07 MDT 2007 SECTION VIII, DIVISION 9.7.2 a) b) Documentation The results of the analysis shall be documented and signed by the individual in responsible charge of the management of the operation of the vessel This documentation shall include as a minimum: 1) Detailed Process and Instrument Flow Diagrams (P&IDs), showing all pertinent elements of the system associated with the vessel 2) A description of all credible operating and upset scenarios, including scenarios involving fire, and those that result from equipment and instrumentation malfunctions 3) An analysis showing the maximum pressure that can result from each of the scenarios examined in paragraph 9.7.2.a.2) above 4) A detailed description of any instrumentation and control system that is used to limit the system pressure, including the identification of all truly independent redundancies and a reliability evaluation (qualitative or quantitative) of the overall safety system 5) A statement that the user certifies that the persons conducting the analysis (see paragraph 9.7.1.d) required by paragraph 9.7.1.c) is qualified to perform this analysis Prior to initial operation, the documentation shall be made available to the regulatory and enforcement authorities having jurisdiction at the site where the vessel will be installed The user is cautioned that prior jurisdictional acceptance may be required 9.7.3 Manufacturer’s Data Report The Manufacturer's Data Report for pressure vessels shall state that the vessel will be provided with overpressure protection by system design, and it shall be noted on the Data Report that prior jurisdictional acceptance may be required ```,,,,,,``,`,``,,`````,`,`,``-`-`,,`,,`,`,,` - Copyright ASME International Provided by IHS under license with ASME No reproduction or networking permitted without license from IHS 9-5 Licensee=Chevron Corp/5912388100 Not for Resale, 08/28/2008 13:31:07 MDT 2007 SECTION VIII, DIVISION ANNEX 9.A BEST PRACTICES FOR THE INSTALLATION AND OPERATION OF PRESSURE RELIEF DEVICES 9.A.1 Introduction This Annex provides additional guidance for design of pressure relief device installations This Annex is a supplement to the installation requirements provided in Part Note that there may be jurisdictional requirements related to the installation of pressure relief devices 9.A.2 Provisions for the Installation of Stop Valves in the Relief Path 9.A.2.1 General The general provisions for the installation of pressure relieving devices are covered in paragraph 9.6 The following paragraphs contain requirements for system and stop valve design when stop valves are to be located within the relief path These stop valves are sometimes necessary for the continuous operation of processing equipment of such a complex nature that shutdown of any part of it is not feasible or not practical The requirements cover stop valves provided upstream and downstream of pressure relief valves, provided in the relief path where there is normally a process flow and in a relief path where fire is the only potential source of overpressure 9.A.2.2 Stop Valves Located in the Relief Path 9.A.2.2.1 General a) A stop valve(s) located within the relief path is not allowed except as permitted by paragraphs 9.A.2.2.5, 9.A.2.2.6, 9.A.2.2.7 and 9.A.2.2.8 below, and only when specified by the user The responsibilites of the user are summarized in paragraph 9.A.2.2.3 The specific requirements of paragraphs 9.A.2.2.5, 9.A.2.2.6, 9.A.2.2.7 and 9.A.2.2.8 are not intended to allow for operation above the maximum allowable working pressure b) The pressure relief path shall be designed such that the pressure in the equipment being protected does not exceed the maximum allowable working pressure before the pressure at the pressure relief device reaches its set pressure and the pressure does not exceed the allowable overpressure limits of Section VIII, Division 9.A.2.2.2 Definitions a) b) Administrative Controls are procedures that, in combination with mechanical locking elements, are intended to ensure that personnel actions not compromise the overpressure protection of the equipment They include, as a minimum: 1) Documented Operation and Maintenance Procedures, 2) Operator and Maintenance Personnel Training in the above procedures The Pressure Relief Path consists of all equipment, pipe, fittings and valves in the flow path between any protected equipment item and its pressure relieving device and the pressure relieving device and the discharge point of the relieving stream Stop valves within a pressure relief path include, but are not limited to, those located directly upstream and downstream of the pressure relief device that may be provided exclusively for pressure relief device maintenance Copyright ASME International Provided by IHS under license with ASME No reproduction or networking permitted without license from IHS 9-6 Licensee=Chevron Corp/5912388100 Not for Resale, 08/28/2008 13:31:07 MDT ```,,,,,,``,`,``,,`````,`,`,``-`-`,,`,,`,`,,` - (INFORMATIVE) 2007 SECTION VIII, DIVISION c) Valve Operation Controls are devices used to ensure that stop valves within the pressure relief path are in their proper (open/closed) position They include the following: 1) Mechanical Interlocks which are designed to prevent valve operations which could result in the blocking of a pressure relief path before an alternative pressure relief path is put into service 2) Instrumented Interlocks which function similar to mechanical interlocks, except that instrument permissives and/or overrides are used instead of mechanical linkages/devices to prevent valve positions that block the pressure relief path 3) Three-way valves designed to prevent a flow path from being blocked without another flow path being simultaneously opened ```,,,,,,``,`,``,,`````,`,`,``-`-`,,`,,`,`,,` - d) Valve Failure Controls are measures taken in valve design, configuration, and/or orientation of the stop valve with the purpose of preventing an internal failure of a stop valve from closing and blocking the pressure relief path An example of valve failure controls is the installation of gate valves with the stem oriented at or below the horizontal position e) A Full Area Stop Valve is a valve in which the flow area of the valve is equal to or larger than the inlet flow area of the pressure relief device f) Mechanical Locking Elements are elements that when installed on a stop valve, provide a physical barrier to the operation of the stop valve, such that the stop valve is not capable of being operated unless a deliberate action is taken to remove or disable the element Such elements when used in combination with administrative controls, ensure that the equipment overpressure protection is not compromised by personnel actions Examples of mechanical locking elements include locks (with or without chains) on the stop valve handwheels, levers, or actuators, and plastic or metal straps (car seals) that are secured to the valve in such a way that the strap must be broken to operate the stop valve g) A Management System is the collective application of administrative controls, valve operation controls, and valve failure controls, in accordance with the applicable requirements of this Division 9.A.2.2.3 Responsibilities The user has the responsibility to establish and maintain a management system that ensures that a vessel is not operated without overpressure protection These responsibilities include, but are not limited to, the following: a) Deciding and specifying if the overpressure protection system will allow the use of stop valves(s) located in the relief path b) Establishing the pressure relief philosophy and the administrative controls requirements c) Establishing the required level of reliability, redundance, and maintenance of instrumented interlocks, if used d) Establishing procedures to ensure that the equipment is adequately protected against overpressure e) Ensuring that authorization to operate indentified valves is clear and that personnel are adequately trained for the task f) Establishing management systems to ensure that administrative controls are effective g) Establishing the analysis procedures and basis to be used in determining the potential levels of pressure if the stop valve(s) is closed h) Ensuring that the analysis described in paragraph 9.A.2.2.3.g is conducted by personnel who are qualified and experienced with the analysis procedure i) Ensuring that the other system components are acceptable for the potential levels of pressure established in paragraph 9.A.2.2.3.g j) Ensuring that the results of the analysis described in paragraph 9.A.2.2.3.g are documented and reviewed and accepted in writing by the individual responsible for the operation of the vessel and valves Copyright ASME International Provided by IHS under license with ASME No reproduction or networking permitted without license from IHS 9-7 Licensee=Chevron Corp/5912388100 Not for Resale, 08/28/2008 13:31:07 MDT 2007 SECTION VIII, DIVISION k) Ensuring that the administrative controls are reviewed and accepted in writing by the individual responsible for operation of the vessel and valves 9.A.2.2.4 Requirements of Procedures/Management Systems a) Procedures shall specify that valves requiring mechanical locking elements and/or valve operation controls and/or valve failure controls shall be documented and clearly identified as such b) The Management System shall document the administrative controls (training and procedures), the valve controls, and the performance of the administrative controls in an auditable form for management review 9.A.2.2.5 Stop Valves Provided in Systems for Which the Pressure Originates Exclusively From an Outside Source A vessel or system for which the pressure originates from an outside source exclusively may have individual pressure relieving devices on each vessel, or connected to any point on the connecting piping, or on any one of the vessels to be protected Under such an arrangement, there may be stop valve(s) between any vessel and the pressure relieving devices, and these stop valve(s) need not have any administrative controls, valve operation controls, or valve failure controls, provided that the stop valves also isolate the vessel from the source of pressure 9.A.2.2.6 Stop Valves Provided Upstream or Downstream of the Pressure Relief Device Exclusively for Maintenance of That Device Full area stop valve(s) may be provided upstream and/or downstream of the pressure relieving device for the purpose of inspection, testing and repair of the pressure relief device or discharge header isolation, provided that, as a minimum, the following requirements are complied with: c) Administrative controls are provided to prevent unauthorized valve operation d) Valves are provided with mechanical locking elements e) Valve failure controls are provided to prevent accidental valve closure due to mechanical failure f) Procedures are in place to provide pressure relief protection during the time when the system is isolated from its pressure relief path These procedures shall ensure that when the system is isolated from its pressure relief path, an authorized person shall continuously monitor the pressure conditions of the vessel and shall be capable of responding promptly with documented, pre-defined actions, either stopping the source of overpressure or opening alternative means of pressure relief This authorized person shall be dedicated to this task and shall have no other duties when performing this task g) The system shall be isolated from its pressure relief path for only the time required to test, repair, and/or replace the pressure relief device 9.A.2.2.7 Stop Valves Provided in the Pressure Relief Path Where There is Normally Process Flow Stop valve(s), excluding remotely operated valves, may be provided in the relief path where there is normally process flow, provided the requirements in paragraphs 9.A.2.2.7.a and 9.A.2.2.7.b, as a minimum, are complied with These requirements are based on the overpressure scenarios involving accidental closure of a single stop valve within the relief path (see paragraph 9.A.2.2.3.g) The accidental closure of these stop valve(s) in the pressure relief system need not be considered in the determination of the specified design pressure in Part of this Division a) The flow resistance of the valve in the full open position does not reduce the relieving capacity below that required by paragraph 9.1.3 b) The closure of the valve will be readily apparent to the operators such that corrective action, in accordance with documented operating procedures, is required and: 1) If the pressure due to closure of the valve cannot exceed 116% of the maximum allowable working pressure, then no administrative controls, or valve failure controls are required, or ```,,,,,,``,`,``,,`````,`,`,``-`-`,,`,,`,`,,` - Copyright ASME International Provided by IHS under license with ASME No reproduction or networking permitted without license from IHS 9-8 Licensee=Chevron Corp/5912388100 Not for Resale, 08/28/2008 13:31:07 MDT 2007 SECTION VIII, DIVISION 2) 3) If the pressure due to closure of the valve cannot exceed the following: i) the documented test pressure, multiplied by the ratio of stress value at the design temperature to the stress value at the test temperature, or ii) if the test pressure is calculated per Part 8, paragraph 8.2.1.e , in addition to the stress ratio specified in paragraph 9.A.2.2.7.b.2.i, the test pressure shall also be multiplied by the ratio of the nominal thickness minus the corrosion allowance to the nominal thickness then, as a minimum, administrative controls and mechanical locking elements are required, or If the pressure due to closure of the valve could exceed the pressure in paragraph 9.A.2.2.7.b.2 , then the user shall either: i) eliminate the stop valve, or ii) apply administrative controls, mechanical locking elements, valve failure controls, and valve operation controls, or iii) provide a pressure relief device to protect the equipment that could be overpressured due to closure of the stop valve 9.A.2.2.8 Stop Valves Provided in the Relief Path of Equipment Where Fire is the Only Potential Source of Overpressure Full area stop valves located in the relief path of equipment where fire is the only potential source of overpressure not require mechanical locking elements, valve operation controls, or valve failure controls provided the user has documented operating procedures requiring the equipment isolated from its pressure relief path is depressured and free of all liquids 9.A.3 Inlet Piping Pressure Drop for Pressure Relief Valves For pressure relief valves, the flow characteristics of the upstream system shall be such that the cumulative total of all non-recoverable inlet losses shall not exceed 3% of the valve set pressure The inlet pressure losses shall be determined accounting for all fittings in the upstream system, including rupture disks installed in the pressure relief valve inlet piping, and shall be based on the valve nameplate capacity corrected for the characteristics of the flowing fluid 9.A.4 Discharge Lines from Pressure Relief Devices a) Where it is feasible, the use of a short discharge pipe or vertical riser, connected through long-radius elbows from each individual device, blowing directly to the atmosphere, is recommended For pressure relief valves, such discharge pipes shall be at least of the same size as the valve outlet Where the nature of the discharge permits, telescopic (sometimes called "broken") discharge lines, whereby condensed vapor in the discharge line, or rain, is collected in a drip pan and piped to a drain, are recommended This construction has the further advantage of not transmitting discharge pipe strains to the pressure relief device In these types of installations, the backpressure effect will be negligible, and no undue influence upon normal operation of the pressure relief device can result b) When discharge lines are long, or where outlets of two or more pressure relief devices are connected into a common line, the effect of the back pressure on pressure relief device operation and capacity shall be considered The sizing of any section of a common discharge header downstream from each of the two or more pressure relief devices that may reasonably be expected to discharge simultaneously shall be based on the total of their outlet areas, with due allowance for the pressure drop in all downstream sections Use of specially designed devices suitable for use on high or variable backpressure service should be considered c) The flow characteristics of the discharge system of high lift, top guided direct spring loaded pressure relief valves or pilot-operated pressure relief valves in compressible fluid service shall be such that the static pressure developed at the discharge flange of a conventional direct spring loaded pressure relief valve will not exceed 10% of the set pressure when flowing at rated capacity Other valve types exhibit various degrees of tolerance to back pressure and the Manufacturer's recommendation should be followed ```,,,,,,``,`,``,,`````,`,`,``-`-`,,`,,`,`,,` - Copyright ASME International Provided by IHS under license with ASME No reproduction or networking permitted without license from IHS 9-9 Licensee=Chevron Corp/5912388100 Not for Resale, 08/28/2008 13:31:07 MDT 2007 SECTION VIII, DIVISION d) All discharge lines shall be run as directly as practicable to the point of final release for disposal For the longer lines, due consideration shall be given to the advantage of long-radius elbows, avoidance of close-up fittings, minimizing line strains and using well-known means of support to minimize line sway and vibration under operating conditions e) Provisions should be made in all cases for adequate drainage of discharge lines f) It is recognized that no simple rule can be applied generally to fit the many installation requirements Installations vary from simple short lines that discharge directly to the atmosphere to the extensive manifold discharge piping systems where the quantity and rate of the product to be disposed of requires piping to a distant safe place 9.A.5 Cautions Regarding Pressure Relief Device Discharge into a Common Header Because of the wide variety of types and kinds of pressure relief devices, it is not considered advisable to attempt a description of the effects produced by discharging them into a common header Several different types of pressure relief devices may conceivably be connected into the same discharge header and the effect of backpressure on each type may be radically different Data compiled by the Manufacturers of each type of pressure relief device used should be consulted for information relative to its performance under the conditions anticipated 9.A.6 9.A.6.1 Pressure Differentials (Operating Margin) for Pressure Relief Valves General a) Due to the variety of service conditions and the various designs of pressure relief valves, only general guidance can be given regarding the differential between the set pressure of the pressure relief valve and the operating pressure of the vessel b) Providing an adequate pressure differential for the application will minimize operating difficulty The following is general advisory information on the characteristics of the intended service and of the pressure relief valves that may bear on the proper pressure differential selection for a given application These considerations should be reviewed early in the system design since they may dictate the maximum allowable working pressure of the system 9.A.6.2 Considerations for Establishing the Operating Margin 9.A.6.2.1 Process Conditions a) To minimize operational problems, the user should consider not only normal operating conditions of fluids, pressures, and temperatures, but also start-up and shutdown conditions, process upsets, anticipated ambient conditions, instrument response times, pressure surges due to quick closing valves, etc b) When such conditions are not considered, the pressure relief valve may become, in effect, a pressure controller, a duty for which it is not designed c) Additional consideration should be given to hazard and pollution associated with the release of the fluid Larger differentials may be appropriate for fluids that are toxic, corrosive, or exceptionally valuable 9.A.6.2.2 Pressure Relief Valve Characteristics a) The blowdown characteristic and capability is the first consideration in selecting a compatible pressure relief valve and operating margin After a self-actuated release of pressure, the pressure relief valve must be capable of reclosing above the normal operating pressure For example, if the pressure relief valve is set at 690 kPa (100 psig) with a 7% blowdown, it will close at 641 kPa (93 psig) The operating pressure must be maintained below 641 kPa (93 psig) in order to prevent leakage or flow from a partially open valve ```,,,,,,``,`,``,,`````,`,`,``-`-`,,`,,`,`,,` - Copyright ASME International Provided by IHS under license with ASME No reproduction or networking permitted without license from IHS 9-10 Licensee=Chevron Corp/5912388100 Not for Resale, 08/28/2008 13:31:07 MDT b) Users should exercise caution regarding the blowdown adjustment of large spring-loaded valves Test facilities, whether owned by Manufacturers, repair houses, or users, may not have sufficient capacity to accurately verify the blowdown setting The settings cannot be considered accurate unless made in the field on the actual installation c) Pilot-operated valves represent a special case from the standpoints of both blowdown and tightness The pilot portion of some pilot-operated valves can be set at blowdowns as short as 2% This characteristic is not, however, reflected in the operation of the main valve in all cases The main valve can vary considerably from the pilot depending on the location of the two components in the system If the pilot is installed remotely from the main valve, significant time and pressure lags can occur, but reseating of the pilot assures reseating of the main valve The pressure drop in the connecting piping between the pilot and the main valve must not be excessive; otherwise, the operation of the main valve will be adversely affected The tightness of the main valve portion of these combinations is considerably improved above that of conventional valves by pressure loading the main disk or by the use of soft seats or both Despite the apparent advantages of pilot-operated valves, users should be aware that they should not be employed in abrasive or dirty service, in applications where coking, polymerization, or corrosion of the wetted pilot parts can occur, or where freezing or condensation of the fluid at ambient temperatures is possible For all applications, the pressure relief valve Manufacturer should be consulted prior to selecting a valve of this type d) Tightness capability is another factor affecting valve selection, whether spring-loaded or pilot-operated It varies somewhat depending on whether metal or resilient seats are specified, and also on such factors as corrosion or temperature The required tightness and test method should be specified to comply at a pressure no lower than the normal operating pressure of the process A recommended procedure and acceptance standard is given in API Standard 527, Seat Tightness of Pressure Relief Valves It should also be noted that any degree of tightness obtained should not be considered permanent Service operation of a valve almost invariably reduces the degree of tightness e) Application of special designs such as O-rings or resilient seats should be reviewed with the pressure relief valve Manufacturer f) The anticipated behavior of the pressure relief valves includes allowance for a plus-or-minus tolerance on set pressure that varies with the pressure level Installation conditions, such as backpressure, variations, and vibrations influence selection of special designs and may require an increase in the differential pressure (operating margin) 9.A.6.2.3 General Recommendations for Pressure Differentials (Operating Margin) The following pressure differentials are recommended unless the pressure relief valve has been designed or tested in a specific or similar service, and a smaller differential has been recommended by the Manufacturer a) A minimum difference of 35 kPa (5 psi) is recommended for set pressures to 485 kPa (70 psi) In this category, the set pressure tolerance is + 13.8 kPa (+2 psi), and the differential to the leak test pressure is 10% or 35 kPa (5 psi), whichever is greater b) A minimum differential of 10% is recommended for set pressures from 490 to 6900 kPa (71 psi to 1000 psi) In this category, the set pressure tolerance is + 3% and the differential to the leak test pressure is 10% c) A minimum differential of 7% is recommended for set pressures above 6900 kPa (1000 psi) In this category, the set pressure tolerance is + 3% and the differential to the leak test pressure is 5% d) Pressure relief valves having small seat sizes will require additional maintenance when the pressure differential approaches these recommendations Copyright ASME International Provided by IHS under license with ASME No reproduction or networking permitted without license from IHS 9-11 Licensee=Chevron Corp/5912388100 Not for Resale, 08/28/2008 13:31:07 MDT ```,,,,,,``,`,``,,`````,`,`,``-`-`,,`,,`,`,,` - 2007 SECTION VIII, DIVISION 2007 SECTION VIII, DIVISION 9.A.7 Pressure Relief Valve Orientation Spring-loaded pressure relief valves normally should be installed in the upright position with the spindle vertical Where space or piping configuration preclude such an installation, the valve may be installed in other than the vertical position provided that: a) The pressure relief valve design is satisfactory for such position and is acceptable to the Manufacturer of the valve, b) The media is such that solid material will not accumulate at the inlet of the pressure relief valve, and c) Drainage of the discharge side of the pressure relief valve body and discharge piping prevents collection of liquid on the valve disk or in the discharge piping 9.A.8 Reaction Forces and Externally Applied Piping Loads a) The discharge of a pressure relief device imposes reactive flow forces on the device and associated piping The design of the installation may require computation of the bending moments and stresses in the piping and vessel nozzle There are momentum effects and pressure effects at steady state flow as well as transient dynamic loads caused by opening b) Mechanical forces may be applied to the pressure relief device by discharge piping as a result of thermal expansion, movement away from anchors, and weight of any unsupported piping The resultant bending moments on a closed pressure relief device may cause pressure relief valve leakage, damage to rupture disks, and excessive stress in inlet piping The design of the installation should consider these possibilities 9.A.9 Sizing of Pressure Relief Devices for Fire Conditions a) Excessive pressure may develop in pressure vessels by vaporization of the liquid contents and/or expansion of vapor content due to heat influx from the surroundings, particularly from a fire b) Pressure relief systems for fire conditions are usually intended to release only the quantity of product necessary to lower the pressure to a predetermined safe level, without releasing an excessive quantity This control is especially important in situations where release of the contents generates a hazard because of flammability or toxicity c) Under fire conditions, consideration must also be given to the possibility that the safe pressure level for the vessel will be reduced due to heating of the vessel material, with a corresponding loss of strength d) Several equations have evolved over the years for calculating the pressure relief capacity required under fire conditions The major differences involve heat flux rates There is no single equation yet developed which takes into account all of the many factors that could be considered in making this determination When fire conditions are a consideration in the design of a pressure vessel, the following references which provide recommendations for specific installations may be used: 1) API Recommended Practice 520, Sizing, Selection, and Installation of Pressure-Relieving Systems in Refineries, Part – Sizing and Selection, Seventh Edition, January 2000, American Petroleum Institute, Washington, DC 2) API Standard 521, Pressure-Relieving and Depressuring Systems, Fifth Edition, Jan 2007, American Petroleum Institute, Washington, DC 3) API Standard 2000, Venting Atmospheric and Low-Pressure Tanks (Nonrefrigerated and Refrigerated), Fifth edition, April 1998, American Petroleum Institute, Washington, DC 4) AAR Standard M-1002, Specifications for Tank Cars, 1978, Association of American Railroads, Washington, DC 5) Safety Relief Device Standards: S-l.l, Cylinders for Compressed Gases; S-1.2, Cargo and Portable Tanks; and S-1.3, Compressed Gas Storage Containers, Compressed Gas Association, Arlington, VA Copyright ASME International Provided by IHS under license with ASME No reproduction or networking permitted without license from IHS 9-12 ```,,,,,,``,`,``,,`````,`,`,``-`-`,,`,,`,`,,` - Licensee=Chevron Corp/5912388100 Not for Resale, 08/28/2008 13:31:07 MDT 2007 SECTION VIII, DIVISION 6) NFPA Code Nos 30, 58, 59, and 59A, National Fire Protection Association, Batterymarch Park, Quincy, MA, 02169-7471 7) Pressure-Relieving Systems for Marine Cargo Bulk Liquid Containers, 1973, National Academy of Sciences, Washington, DC 9.A.10 Use of Pressure Indicating Devices to Monitor Pressure Differential If a pressure indicating device is provided to monitor the vessel pressure at or near the set pressure of the pressure relief device, one should be selected that spans the set pressure of the pressure relief device and is graduated with an upper limit that is neither less than 1.25 times the set pressure of the pressure relief device nor more than twice the maximum allowable working pressure of the vessel Additional devices may be installed if desired ```,,,,,,``,`,``,,`````,`,`,``-`-`,,`,,`,`,,` - Copyright ASME International Provided by IHS under license with ASME No reproduction or networking permitted without license from IHS 9-13 Licensee=Chevron Corp/5912388100 Not for Resale, 08/28/2008 13:31:07 MDT 2007 SECTION VIII, DIVISION ```,,,,,,``,`,``,,`````,`,`,``-`-`,,`,,`,`,,` - Copyright ASME International Provided by IHS under license with ASME No reproduction or networking permitted without license from IHS 9-14 Licensee=Chevron Corp/5912388100 Not for Resale, 08/28/2008 13:31:07 MDT ```,,,,,,``,`,``,,`````,`,`,``-`-`,,`,,`,`,,` - Copyright ASME International Provided by IHS under license with ASME No reproduction or networking permitted without license from IHS Licensee=Chevron Corp/5912388100 Not for Resale, 08/28/2008 13:31:07 MDT