as 1210 supplement 1 - unfired pressure vessels - advanced d
TRANSCRIPT
AS 1210 Supp1—1990
Australian Standard
Unfired pressure vessels —Advanced design andconstruction
(Supplement to AS 1210—1989)
This Australian Standard was prepared by Committee ME/1, Boilers and UnfiredPressure Vessels. It was approved on behalf of the Council of Standards Australia on20 October 1989 and published on 2 April 1990.
The following interests are represented on Committee ME/1:
Aluminium Development CouncilAustralian Compressed Air InstituteAustralian Institute for Non-destructive TestingAustralian Institute of EnergyAustralian Institute of PetroleumAustralian Liquefied Petroleum Gas AssociationAustralian Valve Manufacturers AssociationBoiler and Pressure Vessel Manufacturers Association of AustraliaBureau of Steel Manufacturers of AustraliaConfederation of Australian IndustryDepartment of DefenceDepartment of Industrial Affairs, QldDepartment of Labour, S.A.Department of Labour, Vic.Department of Labour and Industry, Tas.Department of Occupational Health, Safety and Welfare, W.A.Department of the Arts, Sport, the Environment, Tourism and TerritoriesElectricity Supply Association of AustraliaInstitute of Metals and Materials AustralasiaInstitution of Engineers AustraliaInsurance Council of AustraliaMetal Trades Industry Association of AustraliaNational Association of Testing Authorities AustraliaRailways of Australia CommitteeSociety of Mechanical Engineers of AustralasiaSugar Research InstituteWelding Technology Institute of AustraliaWork Health Authority, N.T.Workcover, N.S.W.
Review of Australian Standards.To keep abreast of progress in industry, Australian Standards are subjectto periodic review and are kept up to date by the issue of amendments or new edit ions as necessary. It isimportant therefore that Standards users ensure that they are in possession of the latest edition, and anyamendments thereto.
Full details of all Australian Standards and related publications will be found in the Standards AustraliaCatalogue of Publications; this information is supplemented each month by the magazine ‘The AustralianStandard’, which subscribing members receive, and which gives details of new publications, new editionsand amendments, and of withdrawn Standards.
Suggestions for improvements to Australian Standards, addressed to the head office of Standards Australia,are welcomed. Noti fication of any inaccuracy or ambiguity found in an Australian Standard should be madewithout delay in order that the matter may be investigated and appropriate action taken.
This Standard was issued in draft form for comment as DR 88113.
AS 1210 Supp1—1990
Australian Standard
Unfired pressure vessels —Advanced design andconstruction
(Supplement to AS 1210—1989)
First published as AS CB1 Int.6—1969.Revised and redesignated AS 1210 Supplement 1—1979.Second edition 1984.Third edition 1990.
Incorporating:Amdt 1—1995Amdt 2—1997
PUBLISHED BY STANDARDS AUSTRALIA(STANDARDS ASSOCIATION OF AUSTRALIA)1 THE CRESCENT, HOMEBUSH, NSW 2140
ISBN 0 7262 6003 7
AS 1210 Supp1—1990 2
PREFACE
This edition of this Supplement was prepared by the Standards Australia Committeeon Boilers and Unfired Pressure Vessels to supersede Supplement No 1 (June 1984)to AS 1210, SAA Unfired Pressure Vessel Code, Class 1H Pressure Vessels ofAdvanced Design and Construction. It forms part of theSAA Boiler Code(AS 1200)which is referred to in Statutory Regulations in Australia, and which coversrequirements for land installations of shell boilers, water-tube boilers, unfired pressurevessels, pressure piping, welder certification, and related matters.
The Supplement provides for additional classes of vessels which require more precisedesign procedures to ensure that the higher design stresses can be tolerated for theparticular design and that fatigue will be avoided.
Revisions and additions have been made throughout the Supplement.
A major revision in this edition is the introduction of a new classification of weldedvessel (Class 2H) which permits the use of the higher design strengths applicable toClass 1H vessels with reduced levels of non-destructive examination but with therestrictions on the range and the thickness of materials used and the fatigue criteriaunder which the Class 2H vessels may be used. The introduction of requirements forClass 2H vessels was delayed until a full review of the material requirements inAS 1210,SAA Unfired Pressure Vessels Code, for low temperature service had beencarried out.
An alternative method for assessing the need for a detailed fatigue analysis of thevessel and its components has been introduced.
Other revisions in this edition include a change of the membrane stress intensity limitsfor the test condition, clarification of the design strengths to be used in the design offlanges, changes in the requirements for clad plate and for low temperature service andclarification of coverage of cast and forged vessels.
The Supplement deals only with stationary vessels for a specific service whereoperation and maintenance control is fully exercised during the useful life of the vesselby the users in accordance with specified operating requirements for the vessel.
This Supplement lists only those requirements which differ from or are additional tothose for Class 1 vessels in AS 1210. Together with AS 1210 it will directly satisfythe needs of most vessels. For complicated vessels or for vessels that are subject tounusual loads or fatigue, a comprehensive stress/load analysis is required.
This Supplement requires that all vessels be reviewed to ensure that unusual andexcessive loads and fatigue cycling are maintained within safe limits. It prescribesdetailed fatigue analysis where and when necessary. For vessels that are cleared fromsuch a detailed investigation, the same design formulas as given in AS 1210 are used,except where otherwise specified.
Where fatigue, vessel configuration or loading is such that detailed stress analysis isrequired, the degree of such analysis can be determined only by a competent designer.The designer will need to refer to recognized engineering texts and techniques. Someauthoritative national standards such as ANSI/ASME BPV-VIII-2,Boiler and PressureVessel Code: Section VIII — Rules for construction of pressure vessels: Division 2 —Alternative rules, and BS 5500,Specification for unfired fusion welded pressurevessels, provide tested shortcuts to many solutions encountered in advanced vesseldesign. These may be used, where appropriate by the designer as substitutes forfundamental stress analysis.
Acknowledgement is gratefully made to the American Society of Mechanical Engineersfor permission to reproduce certain extracts from the ASME Boiler and PressureVessel Code. In addition, acknowledgement is made of the considerable assistanceprovided by British and other national Standards.
The International Organization for Standardization (ISO) Technical CommitteeISO/TC 11 — Boilers and Pressure Vessels, has prepared a draft InternationalStandard, ISO/DIS 2694,ISO draft recommendation for pressure Vessels, with theobject of achieving agreement regarding uniformity of approach in national standardscovering this subject. At this time, significant differences between the various nationalstandards and ISO/DIS 2694 remain and these differences are still to be resolved.
With the changes introduced by Amendment No. 2, this 1990 edition of AS 1210Supplement 1 is suitable for use with the 1997 edition of AS 1210,Pressure vessels.
3 AS 1210 Supp1—1990
CONTENTS
Page
FOREWORD 5
SECTION S1. SCOPE AND GENERAL REQUIREMENTSS1.1 SCOPE . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6S1.3 APPLICATION OF SUPPLEMENT . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6S1.6 CLASSES OF VESSEL CONSTRUCTION . . . . . . .. . . . . . . . . . . . . . . . . . . . . . 6S1.7 APPLICATION OF VESSEL CLASSES AND TYPES . .. . . . . . . . . . . . . . . . . . . 6S1.8 DEFINITIONS . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6S1.12 DESIGNATION . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6S1.13 REFERENCED DOCUMENTS . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
SECTION S2. MATERIALSS2.1 MATERIAL SPECIFICATIONS . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8S2.3 ALTERNATIVE MATERIAL AND COMPONENT SPECIFICATIONS . .. . . . . . . 8S2.4 MATERIAL IDENTIFICATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8S2.6 MATERIAL REQUIREMENTS FOR LOW TEMPERATURE SERVICE . .. . . . . . 8S2.7 MATERIAL REQUIREMENTS FOR HIGH TEMPERATURE SERVICE . .. . . . . 8S2.8 NON-DESTRUCTIVE TESTING OF MATERIALS . . . . . . .. . . . . . . . . . . . . . . . 8
SECTION S3. DESIGNS3.1 GENERAL DESIGN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . 9S3.2 DESIGN CONDITIONS . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15S3.3 DESIGN STRENGTHS . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15S3.5 WELDED, RIVETED AND BRAZED JOINTS . .. . . . . . . . . . . . . . . . . . . . . . . . 17S3.7 THIN-WALLED CYLINDRICAL AND SPHERICAL SHELLS SUBJECT TO
INTERNAL PRESSURE AND COMBINED LOADINGS . .. . . . . . . . . . . . . . . . . 17S3.8 THICK-WALLED CYLINDRICAL AND SPHERICAL SHELLS SUBJECT TO
INTERNAL PRESSURE . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17S3.9 CYLINDRICAL AND SPHERICAL SHELLS SUBJECT TO EXTERNAL
PRESSURE . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17S3.10 CONICAL ENDS AND REDUCERS SUBJECT TO INTERNAL PRESSURE . . . . 17S3.11 CONICAL ENDS AND REDUCERS SUBJECT TO EXTERNAL PRESSURE . . . . 17S3.12 DISHED ENDS SUBJECT TO INTERNAL PRESSURE . .. . . . . . . . . . . . . . . . . 17S3.13 DISHED ENDS SUBJECT TO EXTERNAL PRESSURE . .. . . . . . . . . . . . . . . . . 18S3.14 DISHED ENDS — BOLTED SPHERICAL TYPE . .. . . . . . . . . . . . . . . . . . . . . . 18S3.15 UNSTAYED FLAT ENDS AND COVERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18S3.16 STAYED FLAT ENDS AND SURFACES . .. . . . . . . . . . . . . . . . . . . . . . . . . . . 18S3.17 FLAT TUBEPLATES . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18S3.18 OPENINGS AND REINFORCEMENTS . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18S3.19 CONNECTIONS AND BRANCHES . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19S3.21 BOLTED FLANGED CONNECTIONS . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19S3.22 PIPES AND TUBES . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19S3.23 JACKETED CONSTRUCTION . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19S3.24 VESSEL SUPPORTS . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19S3.25 ATTACHED STRUCTURES AND EQUIPMENT . .. . . . . . . . . . . . . . . . . . . . . . 19S3.26 TRANSPORTABLE VESSELS . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
SECTION S4. CONSTRUCTION . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
AS 1210 Supp1—1990 4
PageSECTION S5. TESTING AND QUALIFICATIONS
S5.10 HYDROSTATIC TESTS . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20S5.11 PNEUMATIC TESTS . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21S5.12 EXPERIMENTAL STRESS ANALYSIS . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21S5.13 LEAK TEST . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22S5.19 NON-DESTRUCTIVE EXAMINATION OF FORGINGS . .. . . . . . . . . . . . . . . . . 22
SECTION S6. WINSPECTION . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
SECTION S7. MARKING AND REPORTSS7.1 MARKING REQUIRED . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
SECTION S8. PROTECTIVE DEVICES AND OTHER FITTINGS . .. . . . . . . . . . . . . . . . . 24
SECTION S9. PROVISIONS FOR DESPATCH . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
APPENDICESSA BASIS OF DESIGN STRENGTH (f) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25SB POROSITY CHARTS . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27SC PRACTICE TO AVOID FATIGUE CRACKING . .. . . . . . . . . . . . . . . . . . . . . . . 27SD RECOMMENDED CORROSION PREVENTION PRACTICE . .. . . . . . . . . . . . . 34SE INFORMATION TO BE SUPPLIED BY THE PURCHASER TO THE
MANUFACTURER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34SF INFORMATION TO BE SUPPLIED BY THE MANUFACTURER . . . . . . .. . . . . 34SH DESIGN REQUIREMENTS FOR LOADINGS AND COMPONENTS NOT
COVERED BY SECTION 3 . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35SK LOW TEMPERATURE VESSELS . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42SR LIST OF REFERENCED DOCUMENTS . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Copyright STANDARDS AUSTRALIA
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Care should be taken to ensure that material used is from the current edition of the Standard and that it is updated whenever the Standard isamended or revised. The number and date of the Standard should therefore be clearly identified.
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5 AS 1210 Supp1—1990
FOREWORD
The application of the several Standards that form the SAA Boiler Code may give riseto a need for consideration of unusual and other designs which do not comply in allrespects with the requirements of the relevant Standard or which are not adequatelycovered in any Standard.
Where it is desired to use materials or methods which do not comply with therequirements of, or are not adequately covered by the relevant Standard, designsincorporating such departures should be submitted to the relevant Inspecting Authorityfor approval. Where necessary, Standards Australia Committee ME/1, Boilers andUnfired Pressure Vessels, may be asked to serve in an advisory capacity in thedetermination of the suitability of such designs. (See also Clause 1.4.)
It is emphasized that this activity of the committee is limited to technical aspects ofthe Code and that the committee has no power or jurisdiction to adjudicate uponcontractual matters or regulatory matters or the duties of any persons concerned withthe subject of the submission.
It is further emphasized that the committee will undertake consideration of only thosematters which relate to interpretation of, or proposed changes to, the Standards forwhich it is responsible. In particular it will not consider or make recommendationsindicating approval of proprietary equipment, materials, components, or methods.
A method developed by the committee for communicating its findings is the use ofRulings. A Ruling is issued in reply to a specific enquiry from a specific organizationand applies only to the set of circumstances referenced in the Ruling. Rulings may beused by the authorities as the basis for approval of the particular application or forapproval of similar submissions from other organizations. Current Rulings are availableunder the reference AS 1200 Supplement 1.
Where the committee judges the subject to be suitable, a Ruling may be incorporatedin an amendment to the relevant Standard, whereupon the Ruling is withdrawn. If thetiming is appropriate, the finding of the committee may be issued directly as anamendment.
NOTES:1. In the past some Rulings have been designated ‘Commit tee Opinions’, but this term is no longer used.2. In the past, the commit tee has also issued ‘Interpretations’ which were considered to be equivalent to
an amendment. The practice has been discontinued, and all Interpretations have now been withdrawn.
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AS 1210 Supp1—1990 6
STANDARDS AUSTRALIA
Australian StandardUnfired pressure vessels — Advanced design and construction
(Supplement to AS 1210—1989)
SECTION S1. SCOPE AND GENERAL REQUIREMENTS
S1.1 SCOPE.Clause 1.1 applies with the followingadditions:
Supplement 1 (hereafter referred to as ‘the Supplement’or ‘this Supplement’) specifies requirements for twoadditional classes of vessel identified as Class 1H andClass 2H with the latter further subdivided intoclassifications 2HA and 2HB, and for cast and forgedvessels, which —
(a) utilize advanced design and construction methods;
(b) generally permit design strengths higher than thosespecified in AS 1210; and
(c) comply with the requirements specified in AS 1210for cast, forged or Class 1 welded vessels asappropriate, except as modified by this Supplement.
This Supplement does not apply to transportable vesselsnor does it apply to vessels of riveted or brazedconstruction. Only those requirements which supplementor differ from those specified in AS 1210 for cast,forged or Class 1 welded construction are specified inthis Supplement.
S1.3 APPLICATION OF SUPPLEMENT. Clause 1.3applies except that the first paragraph shall be replacedby the following:
The requirements of this Supplement are specificallyintended for application to unfired pressure vesselshaving —
(a) design pressures above the curves in Figures 1.3.1and 1.3.2; and
(b) operating temperature limits of various materialsand components as stated in the appropriate Sectionof this Supplement.
NOTE: The Supplement does not specify a limitation on pressuresand is not all-inclusive for all types of construction. For very highpressures, some additions to or deviations from the requirements ofthis Supplement, to the satisfaction of the Inspecting Authority andpurchaser, may be necessary.
S1.6 CLASSES OF VESSEL CONSTRUCTION.Clause 1.6 applies with the following addition:
This Supplement specifies the requirements for twoadditional classes of vessels, viz Class 1H and Class 2H,and the latter is subdivided into classifications 2HA and2HB.
The range of materials permitted for Class 2Hconstruction (see Clause S2.1.1) is limited but the extentof non-destructive examination may be reduced from thatrequired for Class 1H construction (see Clause S5.3.4.1)provided that criteria for design against fatigue failure,as appropriate for Class 2HA and Class 2HBrespectively, are fulfilled (see Clause S3.1.5.4).
S1.7 APPLICATION OF VESSEL CLASSES ANDTYPES. Clause 1.7 applies with the followingmodification:
S1.7.2.4Mixed classes of construction.Clause 1.7.2.4does not apply to this Supplement and the followingshall be substituted:
See Clause S3.1.5.4 for the permissible mixing ofcomponents of Class 1H, Class 2HA, and Class 2HBconstruction.
S1.8 DEFINITIONS. Clause 1.8 applies, with thefollowing additions and modifications to particularClauses.
S1.8.10 Design strength.Clause 1.8.10 does not applyto this Supplement and the following shall be substituted:
Design strength (f)— the maximum allowable stressvalue for use in the equations for the calculation ofpressure parts, and the basis for determining stressintensity limits (see Clause S3.3).
S1.8.24 Parties concerned.Clause 1.8.24 does not applyto this Supplement and the following shall be substituted:
Parties concerned— the purchaser, the manufacturer,Inspecting Authority, and the designer (seeClause S3.1.2).
S1.12 DESIGNATION. Clause 1.12 does not apply tothis Supplement and the following shall be substituted:
S1.12 DESIGNATION. Unfired pressure vesselsconstructed to this Supplement shall be designated by thenumber of the Standard to which it is a supplement, i.e.AS 1210, and the method or class of construction:
For Class 1H welded construction . . AS 1210 — 1HFor Class 2HA welded construction AS 1210 — 2HAFor Class 2HB welded construction AS 1210 — 2HBFor cast construction . .. . . . . . . . AS1210 — CHFor forged construction . .. . . . . . . AS1210 — FHFor mixed construction — an appropriate combinationof symbols, e.g. . .. . . . . . . . AS1210 — 1H/2HA
S1.13 REFERENCED DOCUMENTS. Clause 1.13applies and this Supplement makes reference to thefollowing documents:
AS1065 Non-destructive testing — Ultrasonic testing
of carbon and low alloy steel forgings
1200 SAA Boiler Code
1200 Supplement 1 — Rulings to the SAA BoilerCode
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7 AS 1210 Supp1—1990
1210 SAA Unfired Pressure Vessels Code
1391 Methods for tensile testing of metals
1548 Steel plates for boilers and pressure vessels
1710 Non-destructive testing of carbon and lowalloy steel plate — Test methods and qualityclassification
ISOR 783 Mechanical testing of steel at elevated
temperatures — Determination of lower yieldstress and proof stress and proving test
6892 Metallic materials — Tensile testing
DIS 2694 Draft recommendations for pressure vessels
ANSI/ASME Boiler and pressure vessel code:
BPV/VIII-2 Section VIII — Rules for constructionof pressure vessels: Division 2 —Alternative rules
ASTMA 578 Specification for straight-beam ultrasonic
examination of plain and clad steel plates forspecial applications
BS3688 Methods for mechanical testing of metals at
elevated temperaturesPart 1: Tensile testing
5500 Specification for unfired fusion weldedpressure vessels
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AS 1210 Supp1—1990 8
SECTION S2. MATERIALS
Section 2 of AS 1210 shall apply, with the followingadditions and modifications to particular Clauses.
S2.1 MATERIAL SPECIFICATIONS. Clause 2.1applies, with the following additions and modificationsto particular Clauses:
S2.1.1 General.Clause 2.1.1 does not apply to thisSupplement and the following shall be substituted:
Any material used in the construction of Class 1Hvessels shall comply with the specification listed inTables 3.3.1(A), 3.3.1(B) and 3.3.1(D) to 3.3.1(H), andshall have the design strengths allocated in Table S3.3.1(i) or (ii).
Any material used in construction of Class 2H vesselsshall be a Group A or Group K steel (see Note)complying with a specification listed in Table 3.3.1(A)or Table 3.3.1(B), and shall have the design strengthallocated in Table S3.3.1(i) or (ii). For Class 2H vessels,the nominal shell plate thickness shall not exceed38 mm.
NOTE: For steel groups, see Appendix P or Tables 3.3.1(A) and3.3.1(B).
S2.3 ALTERNATIVE MATERIAL ANDCOMPONENT SPECIFICATIONS. Clause 2.3applieswith the following modification:
S2.3.3 Use of structural or similar quality steels.Clause 2.3.3 does not apply and the following shall besubstituted:
Structural and similar quality steels shall be used onlywhere requirements of Clause 2.3.4 are complied with.
S2.4 MATERIAL IDENTIFICATION. Clause 2.4applies, with the following additions and modifications.
S2.4.1 Unidentified material.The use of unidentifiedmaterial is not permitted.
Not permitted.
S2.4.2 Material not fully identified. The use of materialnot fully identified is not permitted.
S2.6 MATERIAL REQUIREMENT FOR LOWTEMPERATURE SERVICE. Clause 2.6 applies withthe following additions:
S2.6.2.6Class 2H vessels.For Class 2H vessels, therequired MDMT as determined from Table 2.6.3 shall benot less than 10°C below the MOT for vessel or vesselpart.
S2.6.3.2(e)Modification for liquefied gas.For Class 2Hvessels which contain liquefied gas, the required MDMTat full design strength shall be not more than 10°Chigher than the atmospheric boiling point of the contents.
S2.7 MATERIAL REQUIREMENTS FOR HIGHTEMPERATURE SERVICE. Clause 2.7 applies, withthe following additions and modifications to particularClauses:
S2.7.5 Steels.Clause 2.7.5 applies except that the firstand second paragraphs shall be replaced by thefollowing:
Steels for use at temperatures of 100°C or above shall besupplied with elevated temperature properties verified orhot-tested, except as provided below:
(a) Steels for which elevated temperature properties arespecified in the relevant material specification butwhich have not been hot-tested or verified may beused. The design strength value shall be either aspermitted by Table S3.3.1 or as determined by thefactors in Table SA1.1 of Appendix SA.
(b) Steels for which elevated temperature properties arenot specified in the relevant material specificationmay be used. (See Table S3.3.1(ii) for the designstrength for such steels listed in ANSI/ASMEBPV-VIII-2 or BS 5500.)
Where steel is to be used at a design temperaturedifferent from the standard test temperature in theparticular material specification and is ordered hot-tested,the test shall be carried out at the nearest higher standardtemperature given in the particular material specification.The material shall comply with the requirements of thematerial specification at the test temperature.
S2.8 NON-DESTRUCTIVE TESTING OFMATERIALS. Clause 2.8 applies with the followingaddition:
All plates 100 mm and over in thickness shall beultrasonically examined in accordance with AS 1710 orother approved method, and shall comply with therequirements for Class 2E quality level of AS 1710.
For clad plate, where credit for the thickness of claddingon plate is permitted (see also Clause 3.3.1.2(c)), thebond between the cladding and the baseplate shall beultrasonically examined.
All forgings 100 mm and over in thickness shall beultrasonically examined in accordance with, and shallcomply with the requirements of Clause S5.19.
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9 AS 1210 Supp1—1990
SECTION S3. DESIGN
Section 3 of AS 1210 shall apply, with the followingadditions and modifications to particular Clauses:
S3.1 GENERAL DESIGN. Clause 3.1 applies with thefollowing additions and modifications to particularClauses:
S3.1.2 Design responsibility.Clause 3.1.2 does notapply to this Supplement and the following shall besubstituted:
The design shall be carried out by a designer suitablyqualified and experienced in the design of pressurevessels, who shall be responsible for the design of thevessel in accordance with this Section; and the designconditions shall either be specified by the purchaser (seeAppendix SE) or be specified by the designer andapproved by the purchaser.
A high level of qualification and experience wouldnormally be required of a designer or design organizationcapable of adequately discharging the full requirementsof this Supplement.
The designer may be associated with either the purchaseror the manufacturer, but, if not so associated, thedesigner shall be deemed to be one of the parties in thematters that require agreement of the parties concerned.
S3.1.3 Alternative design methods.Clause 3.1.3 doesnot apply to this Supplement and the following shall besubstituted:
Where an alternative design method is adopted, thegeneral principles, design limits, fabrication, testing, andinspecting requirements of this Supplement shall becomplied with.
In lieu of the requirements contained in this Supplementpertaining to the evaluation of design stress in a vesselor vessel component, it may be permitted to use arigorous mathematical stress analysis, e.g. finite elementmethod, or experimental stress analysis to evaluate theactual design stress. However, where completerequirements for the design of a vessel or vessel regionare not provided in this Section (S3), a complete stressanalysis (see Clause S5.12) shall be performed. Stressvalues obtained from such an analysis shall be used inconjunction with this Supplement to determine theminimum thickness of the vessel or vessel region.
Other design methods may be used (see Foreword)except that the minimum thickness, where only thepressure loading is being considered, shall be not lessthan that required by Clauses S3.7 to S3.13.
S3.1.4 Design against failure.Clause 3.1.4 does notapply to this Supplement and the following shall besubstituted:
The overall design of the vessel shall ensure against anymode of failure. The requirements of this Section (S3)are intended for use to determine the minimum thicknessand other dimensions which provide safety against therisk of —
(a) gross plastic deformation;
(b) incremental collapse;
(c) collapse through buckling;
(d) fatigue cracking; and
(e) creep rupture.
The requirements assume that the material has adequateductility at the service temperature and at the designstresses considered, particularly in the regions of stressconcentration.
Requirements to provide protection against brittlefracture and the requirements to ensure safe performanceat low temperature are given in this Section (S3) and inAS 1210 (see Clause 2.6 and Appendix K).
The requirements of this Section (S3) also providelimited guidance on design against corrosion and applyonly if the materials and welds are not subjected to stresscorrosion in the presence of the product which the vesselis to contain.
S3.1.5 Design criteria.
S3.1.5.1General.The minimum thickness of vessel partssubject only to fluid pressure shall be calculated from theequations given in Clauses S3.7 to S3.13. Where parts ofthe vessel are subject to loads in addition to that of fluidpressure, an equivalent stress intensity based on themaximum shear stress theory shall be calculated. Forloads giving rise to primary membrane stresses, theequivalent stress intensity shall not exceed the designstrength at the design temperature (see Clause S3.3)except as allowed for in Table S3.1.5. Where in additionto the primary membrane stress there are other stressespresent, the equivalent stress intensity at any locationshall not exceed the stress intensity limits given inAppendix SH (see Figure SH1). Clauses S3.7 and S3.13may not ensure against fatigue failure. Thus referenceshall be made to Clauses S3.1.5.4 to S3.1.5.7 todetermine when the above Clauses are applicable orwhen recourse to further fatigue or other analysis isrequired.
Irrespective of whether credit is taken or is not taken forcladding in the computations for the dimensions ofcomponents for integrally clad vessels designed foroperation at other than ambient temperature, calculationof the primary membrane stresses in both the basematerial and the cladding shall be performed and shalltake into account any differential coefficients ofexpansion. The calculated stresses shall not exceed therelevant design strengths given in Table S3.3.1.
S3.1.5.2Maximum shear stress theory.The maximumshear stress at a point is defined as one-half of thealgebraic difference between the largest and the smallestof the three principal stresses. Thus if the principalstresses areσ1, σ2, and σ3 and if σ1 > σ2 > σ3(algebraically) the maximum shear stress is 0.5(σ1 - σ3).The maximum shear stress theory of failure states thatyielding in a component occurs when the maximumshear stress reaches a value equal to the maximum shearstress at the yield stress in a tensile test. In such a tensiletest —
σ1 = fy; σ2 = 0; andσ3 = 0
where
fy = yield stress
and therefore the maximum shear stress is 0.5fy, andyielding occurs when —
0.5(σ1 - σ3) = 0.5fy
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By analogy this equation can be written as —
(σ1 – σ3) = f ′and the right-hand side is then called the equivalentintensity of combined stress or simply ‘stress intensity’.Thus the ‘stress intensity’ is defined as twice themaximum shear stress and is equal to the largestalgebraic difference between any two of the threeprincipal stresses and is directly comparable to yieldstress values found from tensile tests.
S3.1.5.3Application of maximum shear stress theory.Considering a thin cylindrical shell subject only tointernal pressure loading, the following membranestresses apply:
σ1 = hoop stress
=
σ2 = axial stress
=
σ3 = radial stress= -P at inner
surface= 0 at outer surface
where
D = inside diameter An element of a thinof cylinder cylindrical shell
P = internal pressure
f = design strength
t = wall thickness of cylinder
The mean radial stress for thin shells can therefore betaken as —
(σrad) mean =σmean = = -0.5P
From the above equations it then follows that the stressintensity is governed only byσ1 andσ3 and becomes —
f ′ = σ1 – σ3
= – (−0.5P)
= + 0.5P which must not exceed thedesign strengthf
Thust = which is Equation 3.7.3(1) withjoint efficiency equal to 1.
If in addition to internal pressure the vessel part issubject to other loads, the absolute and the relativevalues ofσ1, σ2, andσ3 will vary and could lead to awall thickness larger than that given by, say,Equation 3.7.3(1). Thus, if a slender cylinder is subjectto bending,σ2 could become larger thanσ1 and thecalculated stress intensity would become equal toσ2 – σ3.
S3.1.5.4Designing against fatigue failure — General.During the operation of pressure vessels, important partsmay be subjected to cyclic or repeated stresses. Suchstresses may be caused by —
(a) applications or fluctuations of pressure;
(b) periodic temperature transients;
(c) restrictions of expansion or contraction duringnormal temperature variations;
(d) forced vibrations; or
(e) variations in external loads.
Fatigue cracking will occur during the operational life ifthe fatigue strength of the material used in any part ofthe pressure vessel is exceeded for the particular numberof repeated stress cycles. To prevent fatigue cracking, thelevel of cyclic stress or the expected number of cycles orboth shall be reduced accordingly.
TABLE S3.1.5MEMBRANE STRESS INTENSITY LIMITS FOR VARIOUS LOAD COMBINATIONS
Condition Load combination Membrane stressintensity limit ( kf) Calculated stress limit basis
Design A The design pressure, the dead load of thevessel, the contents of the vessel, theimposed load of any mechanical equipment,and external attachment loads
1.0f (see Note 1) Based on the corroded thickness at designmetal temperature
B Condition A above plus wind forces 1.2f Based on the corroded thickness at designmetal temperature
C Condition A above plus earthquake forcesNOTE: The condition of structuralinstability or buckling must be considered
1.2f Based on the corroded thickness at designmetal temperature
Operation A The actual operating loading conditions.This is the basis of fatigue life evaluation
See Clauses S3.1.5.4 toS3.1.5.7
Based on corroded thickness at operatingpressure and operating metal temperature
Test A The required test pressure, the dead load ofthe vessel, the contents of the vessel, theimposed load of any mechanical equipment,and external attachment loads
See Clause S5.10.2.1 forhydrostatic test, andClause S5.11.4 forpneumatic test
Based on actual design values at testtemperature
NOTES:1. f is the design strength at the design temperature as determined by Clause S3.3.1.2. k is a load factor.
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The alternative but technically equivalent methods fordetermining the need for a detailed fatigue analysis ofClass 1H, Class 2HA, and Class 2HB vessels are givenin Clauses S3.1.5.5 to S3.1.5.7 inclusive. In the firstmethod, Clauses S3.1.5.5 and S3.1.5.6 specifyrequirements for integral parts of vessels and non-integralparts of vessels respectively, while the second methodgiven in Clause S3.1.5.7 covers both integral andnon-integral parts of the vessel.In designing against fatigue, the designer shall payparticular attention to the possibledeleterious effects of thedesign features listedbelow. Unlesstheir fatiguebehaviouris satisfactorily assessed,their use shall be avoided. Designfeatures to be assessed or avoided include —(i) non-integral constructions, such as the use of pad
type reinforcements or of fillet welded attachments,as opposed to integral construction;
(ii) pipe threaded connections, particularly for pipeoutside diameters in excess of 65 mm;
(iii) stud bolted attachments;(iv) partial penetration welds; and(v) major thickness changes between adjacent members.Where corrosion is likely to be present in the area offatigue, consideration should be given to the use of lowerstress levels and to the extrapolation of the fatigue curvesbeyond 106 cycles if necessary.Procedures for determining compliance with the fatiguerequirements of this Supplement for Class 1H, Class 2HAand Class 2HB vessels and vessel components shall be asspecified in (A), (B) and (C) respectively of thisClause (S3.1.5.4).(A) For Class 1H vessels or vessel components—
provided that the requirements of Clauses S3.1.5.5and S3.1.5.6, or of Clause S3.1.5.7 are fulfilled, itmay be assumed that the requirements of thisSupplement are complied with. If those requirementsare not complied with by any component, peakstresses occurring in that component shall becalculated and a fatigue analysis of that componentshall be carried out.The methodof fatigueanalysis shall be in accordancewith Appendix SC or other approved methods. Inparticular cases, other methods of analysis may beequally applicable, and the use of such methodstogether with safety factors equivalent to those usedin Appendix SC shall be deemed to comply with therequirements of this Supplement.NOTE: Apart from nickel-copper alloy, Appendix SC is notdirectly applicable to non-ferrous metals and alloys. For suchmaterials a fundamental approach may be used (see Foreword).
(B) For Class 2HA vessels and vessel components—provided that the requirements for Class 1H vesselson the need for a detailed fatigue analysis, i.e.Clauses S3.1.5.5 and S3.1.5.6 or Clause S3.1.5.7, arefulfilled, the requirements of this Supplement arecomplied with for Class 2HA vessels. If the aboverequirements are not complied with by anycomponent of the Class 2HA vessel, that componentmay be upgradedto comply in full with requirementsfor Class 1H vessel components, including therequirements for non-destructive examination, and adetailed fatigue analysis, in accordance with therequirements in (A) for Class 1H vessel components,shall be carried out.
NOTE: For Class 2HA vessels, it is permissible to upgrade acomponent or components to Class 1H requirements to satisfylocal fatigue requirements.
(C) For Class 2HB vessels and vesselcomponents— allcomponents both integral and non-integral shallcomply with the requirements specified inClause S3.1.5.6, or as specified for non-integral partsin Clause S3.1.5.7, for parts that do not require adetailed fatigue analysis.NOTE: For Class 2HB vessels, it is not permissible to upgrade acomponentor componentsto Class 2HA or Class 1H requirementsto satisfy local fatigue requirements.
3.1.5.5 Rules to determine need for a detailed fatigueanalysis of integral parts of Class 1H vessels.A detailedfatigue analysis need not be made, provided that all ofConditionA below or all of ConditionB below is satisfied;a detailed fatigue analysis shall be made for those partswhich do not satisfy the conditions. The followingrequirements are applicable to all integral parts of thevessels, including integrally reinforced type nozzles. Forvessels having pad type nozzles or non-integralattachments, the requirements of Clause S3.1.5.6 apply.(a) Condition A. Condition A is applicable to both
ferrous and non-ferrous materials.For ConditionA, a detailed fatigue analysis is notmandatory where the material has a specifiedminimum tensile strength not exceeding 560 MPa forparts other than bolts (see Paragraph SC3 ofAppendix SC for bolts), and where the total of theexpected number of cycles of types (i) plus (ii) plus(iii) plus (iv), defined below, does not exceed 1000:(i) The expected (design) number of full-range
pressure cycles including start-up andshutdown.
(ii) The expected number of operating pressurecycles in which the range of pressure variationexceeds 20 percent of the design pressure.
The number of cycles in which the pressure variationdoes not exceed 20 percent of the design pressureshall be limited as follows except in unusualconfigurations with high stress concentration factors:(A) Ferrous materials — no limit.(B) Non-ferrous materials — 106 cycles.NOTE: Pressure cycles caused by fluctuations in atmosphericconditions need to be considered.
(iii) The effective number of changes in metaltemperature* between any two adjacentpoints† in the pressure vessel, includingnozzles. The effective number of such changesis determined by multiplying the number ofchanges in metal temperature of a certainmagnitude by the factor given below, and byadding the resultingnumbers. The factors are asfollows:
Metal temperature differential°C Factor≤25 . . . . . . . . . . . . . . . . . . . . 0
>25 ≤55 . . . . . . . . . . . . . . . . . . . . 1>55 ≤85 . . . . . . . . . . . . . . . . . . . . 2>85 ≤140 . . . . . . . . . . . . . . . . . . . . 4>140 ≤195 . . . . . . . . . . . . . . . . . . . . 8>195 ≤250 . . . . . . . . . . . . . . . . . . . . 12>250 . . . . . . . . . . . . . . . . . . . . 20
* Thermal protection devices, such as thermal sleeves in nozzles, may be used to reduce temperature dif ferences or thermal shock.† Adjacent points are defined as points which are spaced less than the distance 2 (Rt) from each other, whereR and t are the mean radius
and thickness, respectively, of the vessel, nozzle, f lange, or other component in which the points are located. (Expression 2 (Rt) doesnot apply to flat plates.)
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Example: Consider a design subject to thefollowing metal temperature differentials andnumber of cycles:∆t,°C Cycles
25 . . . . . . . . . . . . . . . . . . . . . . . 100050 . . . . . . . . . . . . . . . . . . . . . . . . 250
220 . . . . . . . . . . . . . . . . . . . . . . . . 5The effective number of changes in metaltemperature is —1000(0) + 250(1) + 5(12) = 310The number used as (iii) in performing thecomparison with 1000 is then 310. Temperaturecycles caused by fluctuations in atmosphericconditions need not be considered.
(iv) Thenumber of temperature cycleswhichcausesthe value of (α1 - α2)∆T to exceed0.000 34 forcomponents involving welds between materialshavingdifferentcoefficientsofexpansionwhereα1 andα2 are the mean coefficients of thermalexpansion and∆T is the operating temperaturerange.NOTE: This does not apply to cladding(see Clause 3.3.1.2). Cladding should be the subject of adetailed analysis of thermal stresses.
(b) Condition B.ConditionB is applicable only to thosematerials which are referred to in Appendix SC, i.e.apart from nickel-copper alloy, it is not applicable tonon-ferrous materials.For Condition B, detailed fatigue analysis is notmandatory where all the following conditions aresatisfied:(i) The expected (design) number of full-range
pressure cycles, including start-up andshutdown, does not exceed the number ofcycles in the applicable fatigue curve ofAppendix SC corresponding to anSa value of 3times thef value found in Table S3.3.1 for thematerial at the operating temperature.
(ii) The expected (design) range of pressure cyclesduring normal operation* does not exceed 33percent of the design pressure multiplied bySa/f, whereSa is the value obtained from theapplicable fatigue curve of Appendix SC forthe specified number of significant pressurefluctuations andf is the design strength for theoperating temperature. If the specified numberof significant pressure fluctuations exceeds 106,theSa value atN = 106 may be used.NOTE: Significant pressure fluctuations are those forwhich the range exceeds the quantity of 33 percent of thedesign pressure multiplied byS/f, whereS = the value ofSa for 106 cycles.
(iii) The temperature difference between any twoadjacent points† of the vessel during normaloperation* and during start-up and shutdownoperation does not exceedSa/(2Eα), whereSa isthe value obtained from the applicable designfatigue curve for the specified number ofstart-up and shutdown cycles,α is the value ofthe instantaneous coefficient of thermalexpansion at the mean value of the temperature
at the two points, and E is the modulus of elasticityat the mean value of the temperatures at the twopoints.(iv) The range of temperature difference between
any two adjacent points* of the vessel doesnot change during normal operation† by morethan the quantitySa/(2Eα), where Sa is thevalue obtained from the applicable designfatigue curve for the total specified number ofsignificant temperature difference fluctuations.A temperature difference fluctuation shall beconsidered to be significant if its total algebraicrange exceeds the quantity S/(2Eα), whereS isthe value ofSa obtained from the applicabledesign curve for 106 cycles.
(v) For components fabricated from materials ofdiffering moduli of elasticity or coefficient ofthermal expansion or both, the total algebraicrangeof temperature fluctuation experienced bythe vessel during normal operation does notexceed the magnitude —Sa/[2(E1α1 - E2α2)]where Sa is the value obtained from theapplicable design fatigue curve for the totalspecified number of significant temperaturefluctuations, E1 and E2 are the moduli ofelasticity, andα1 andα2 are the values of theinstantaneous coefficients of thermal expansionat the mean temperature value involved for thetwo materials of construction. A temperaturefluctuation shall be considered to be significantif its total excursion exceeds the quantity —
S/[2(E1α1 - E2α2)]whereS is the value ofSa obtained from theapplicable design fatigue curve for 106 cycles.If the two materials used have differentapplicable design fatigue curves, the lowervalue of Sa shall be used in applying the rulesof this paragraph.NOTE: This Clause does not apply to cladding (seeClause 3.3.1.2). Cladding should be the subject of adetailed analysis of thermal stresses.
(vi) The specified full range of mechanical loads,excluding pressure but including pipingreactions, does not result in load stressintensities whose range exceeds theSa valueobtained from the applicable design fatiguecurve for the total specified number ofsignificant load fluctuations. If the totalspecifiednumberofsignificantload fluctuationsexceeds 106, the Sa value atN = 106 may beused. A load fluctuation shall be considered tobe significant if the total excursion of loadstress intensity exceeds the valueofSa obtainedfrom the applicable design fatigue curve for 106
cycles.S3.1.5.6Rules to determine need for fatigue analysis ofnozzles with separate reinforcement and of non-integralattachments of Class1H vessels.A fatigue analysis of padtype nozzles and non-integral attachments need not bemade provided that all of ConditionAP below or all ofConditionBP below is satisfied.
* Normal operation is defined as any set of operating conditions other than start -up and shutdown, which are specified for the vessel toperform its intended function.
† Adjacent points are defined as points which are spaced less than the distance 2 (Rt) from each other, whereR and t are the mean radiusand thickness, respectively, of the vessel, nozzle, flange, or other component in which the points are located. (Expression 2 (Rt) doesnot apply to flat plates.)
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In the application of ConditionAP or ConditionBP, allfillet welds and partial penetration welds are non-integralattachments except for the following:
(i) Welds connecting non-pressure parts notsubject to significant cyclic loads ortemperature variations and not closer to agross structural discontinuity than —
whereD = int erna l diameter at the
discontinuity of the shell where theattachment is welded. If a largenozzle is considered to be adiscontinuity, the diameter of thenozzle is used if the attachment iswelded to the nozzle wall, or thediameter of the vessel if theattachment is welded to the vessel.If a knuckle in a dished end isconsidered to be a discontinuity, thediameter of the dish at the knuckle,which will usually be the same asthe vessel diameter, is used.
ts = thickness of the shell where theattachment is welded on
(ii) Welds for attachment of support skirts orother supports involving similar attachmentorientation, where the effective throatdimension of the attachment weld is not lessthan the thickness of the attachment.
(a) Condition AP. ConditionAP is applicable to bothferrous and non-ferrous materials.For ConditionAP, detailed fatigue analysis of padtype nozzles and non-integral attachments is notmandatory where the material has a specifiedminimum tensile strength not exceeding 560 MPafor parts other than bolts (see Paragraph SC3 ofAppendix SC for bolts), and where the total of theexpected number of cycles of types (i) plus (ii) plus(iii) plus (iv), defined below, does not exceed 400.(i) The expected (design) number of full-range
pressure cycles including start-up andshutdown.
(ii) The expected number of operating pressurecycles in which the range of pressure variationexceeds 15 percent of the design pressure. Thenumber of cycles in which the pressurevariation does not exceed 15 percent of thedesign pressure shall be limited as followsexcept in unusual configurations with veryhigh stress concentration factors:(1) Ferrous materials — no limit.(2) Non-ferrous materials — 106 cycles.NOTE: Pressure cycles caused by fluctuations inatmospheric conditions need not be considered.
(iii) The effective number of changes in metaltemperature between any two adjacent pointsin the pressure vessel, including nozzles. Inthe calculation of the temperature differencebetween adjacent points, conductive heattransfer shall be considered only throughwelded or integral cross-sections with noallowance for conductive heat transfer acrossunwelded contact surfaces. The effective
number of changes is determined bymultiplying the number of changes in metaltemperature of a certain magnitude by thefactor given below, and by adding theresulting numbers. The factors are as follows:
Metal temperature differential, Factor°C
≤25 . . . . . . . . . . . . . . . 0>25 ≤55 . . . . . . . . . . . . . . . 1>55 ≤85 . . . . . . . . . . . . . . . 2>85 ≤140 . . . . . . . . . . . . . . . 4>140 ≤195 . . . . . . . . . . . . . . . 8>195 ≤250 . . . . . . . . . . . . . . . 12NOTES:1. If metal temperature differential exceeds 250°C,
detailed analysis is required.2. Temperature cycles caused by fluctuations in
atmospheric conditions need not be considered.Example: Consider a design subject to metal temperaturedifferentials for the following number of times:∆t,°C Cycles25 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .100050 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 250220 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5The effective number of changes in metal temperatureis —
1000(0) + 250(1) + 5(12) = 310The number used as (C) in performing the comparisonwith 400 is then 310.
(iv) The number of temperature cycles whichcauses the value of (α1 - α2)∆T to exceed0.000 34 for components involving weldsbetween materials having different coefficientsof expansion, whereα1 and α2 are the meancoefficients of thermal expansion and∆T isthe operating temperature range.NOTE: This does not apply to cladding (seeClause 3.3.1.2). Cladding should be the subject of adetailed analysis of thermal stresses.
(b) Condition BP. ConditionBP is applicable only tothose materials which are referred to inAppendix SC, i.e. apart from nickel-copper alloy, itis not applicable to non-ferrous materials.
For ConditionBP, detailed fatigue analysis of padtype nozzles and non-integral attachments is notrequired where all the requirements ofClause S3.1.5.5(b) are satisfied by the followingadjusted values:
(i) Use a value of 4 instead of 3 inConditionB(i).
(ii) Use a value of 25 percent instead of33 percent in ConditionB(ii).
(iii) Use a value of 2.7 instead of 2 in thedenominator of ConditionB(iii), (iv), and (v).
S3.1.5.7Alternative method for the determination of needfor fatigue analysis of parts of vessel.ThisClause (S3.1.5.7) provides an alternative to the methodin Clauses S3.1.5.5 and S3.1.5.6 for determining theneed for a detailed fatigue analysis of parts of a vessel.A detailed fatigue analysis of vessels or vesselcomponents need not be made, provided that each part ofthe vessel complies with a relevant path inFigure S3.1.5.7.
NOTE: This method is technically equivalent to the method givenin Clauses S3.1.5.5 and S3.1.5.6 but reference should also be madeto these Clauses for additional information.
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FIGURE S3.1.5.7 FLOW CHART FOR NEED FOR DETAILED FATIGUE ANALYSIS
TABLE S3.1.5.7 VALUES OF Sa/N FOR PLOTTING IN DESIGN FATIGUE CURVES IN APPENDIX SC
POINT Sa N = number of cycles
123456
efef∆P/PeEα∆T/1.5eEα∆T/1.5e∆T(E1α1 − E2α2)/1.5∆S (mechanical other than above)
Full range pressure cycles including start up and shutdownPressure cycles during normal operations whose range > S6 P/efStart up and shutdown cyclesTemperature difference variation ∆T whose range > 1.5S6/ eEαTemperature cycle whose range > 1.5 S6 / e ( E1α1 − E2α2)Mechanical stresses (other than above) whoses stress intensity range < S5
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The notation and calculation parameters used in thisClause are as follows:E = modulus of elasticity at mean temperature of
a part, in megapascalsE1, E2 = modulus of elasticity of two different
materials welded together, in megapascalse = factor from Figure S3.1.5.7Fi = temperature factors as follows
Metal temperature Factor(F i)differential (∆Ti)
≤25 . . . . . . . . . . . . . 0>25 ≤55 . . . . . . . . . . . . . 1>55 ≤85 . . . . . . . . . . . . . 2>85 ≤140 . . . . . . . . . . . . . 4>140 ≤195 . . . . . . . . . . . . . 8>195 ≤250 . . . . . . . . . . . . . 12>250 . . . . . . . . . . . . . 20
f = material design strength, in megapascalsN = number of cyclesN(—) = number of cycles for a given conditionND = expected (design) number of full range
pressure cycles including start-up andshutdown
NF = ΣNiFi
Ni = number of changes in metal temperaturedifference between two points no more than2 (Rt) apart for integral parts of vesselsOR
= number of changes in metal temperaturedifference between any two adjacent points inthe pressure vessel, including nozzles fornon-integral parts
NT = number of temperature cycles which causes(α1 - α2)∆T to exceed 0.000 34 for parts ofdissimilar metals welded together
P = design pressure, in megapascals∆P = pressure variation amplitude, in megapascalsR = mean radius of the vessel, nozzle, flange or
other component in which the points arelocated, in millimetres
Rm = specified minimum tensile strength of materialat room temperature, in megapascals
S6 = Sa for 106 cycles, in megapascalsSa = stress amplitude from fatigue curve, in
megapascals∆S = stress amplitude from causes other than
thermal stress and pressure, in megapascalsT1,T2 = temperature of parts of adjacent dissimilar
metals welded together, in degrees Celsius∆T = temperature difference between two points no
more than 2 (Rt) apart for integral parts ofvessels, in degrees CelsiusOR
= temperature difference between any twoadjacent points in the pressure vessel,including nozzles for non-integral parts (seeNote), in degrees Celsius
t = thickness of the vessel, nozzle, flange or othercomponent in which the points are located, inmillimetres
α = instantaneous coefficient of thermal expansionat the mean temperature of two points lessthan 2 (Rt) apart, in reciprocal kelvins
α1, α2 = coefficient of thermal expansion of twodifferent materials welded together, inreciprocal kelvins
NOTE: Conductive heat transfer is considered only through weldedor integral cross-sections with no allowance for conductive heattransfer across unwelded contact surfaces.
S3.2 DESIGN CONDITIONS.Clause 3.2 applies, withthe following additions and modifications to particularClauses:
S3.2.2.3 Temperature fluctuations from normalconditions. Clause 3.2.2.3 does not apply to thisSupplement and the following shall be substituted:
Where temperature fluctuations from normal conditionsoccur, the vessel shall be designed in accordance withClause S3.1.5.4.
S3.2.3 Loadings.Clause 3.2.3 applies except that the lastparagraph shall be deleted and the following substituted:
(n) Forces due to fluctuating pressure or temperature.
Formal analysis of the effect of loading (h) to (n) isrequired only where it is not possible to demonstrate theadequacy of the design, e.g. by comparison with thebehaviour of comparable vessels.
The conditions under which a fatigue analysis that takesinto account loadings (h) to (n) is not required are set outin Clauses S3.1.5.4 to S3.1.5.7.
S3.3 DESIGN STRENGTHS.Clause 3.3 applies withthe following additions and modifications to particularClauses:
NOTE: Within Clause 3.3 and where appropriate, substitute ‘designstrength (f)’ for ‘design tensile strength’, and ‘Table S3.3.1’ for‘Table 3.3.1’.
S3.3.1 Design strength (f). Clause 3.3.1 applies, exceptfor the revised heading and with the following additionsand modifications to particular Clauses:
S3.3.1.1General.Clause 3.3.1.1 does not apply to thisSupplement and the following shall be substituted:
The design strength (f) values for materials other thanbolting material, used in the construction of vessels tothe requirements of this Supplement are given inTable S3.3.1. These values are based on the materialproperties (see Appendix SA) and —
(a) are the maximum values to be used in the equationspresented by this Section for determining theminimum thickness (or other dimensions) of vesselparts; and
(b) form the basis for the various stress intensity limitswhich are specified in Table S3.1.5 andAppendix SH for loadings or components notcovered by Section 3.
NOTE: Some design strength values listed in Table S3.3.1 maydepart from values obtained by direct application of Appendix SA.
To these values a ligament efficiency (see Clause 3.6)and casting quality factor shall be applied whereappropriate. The casting quality factor shall be 0.70except that a higher factor of 0.90 may be used wherethis factor is justified by the additional testing requiredby Clause 5.9.
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For some vessels operating under special conditions andas required by the design, it may be desirable to adopt areduced design strength to —
(a) limit deflection in close-fitting assemblies;
(b) allow for corrosion fatigue or stress corrosionconditions;
(c) allow for an exceptionally long life; or
(d) provide for other design conditions not intended tobe covered by the stress criteria (see Clause S3.1.5).
S3.3.1.3Bolting. Where bolt tensioning procedures areestablished and detailed stress analysis of the bolted jointis made, the alternative higher stress values as given inANSI/ASME BPV-VIII-2 may be used. In the absenceof the above procedure and analysis, bolt strengths aslisted in Table 3.21.5 shall be used.
TABLE S3.3.1 DESIGN STRENGTH (f) VALUES.Table 3.3.1 shall apply except as specified in (a), (b),and (c) below or as noted otherwise in this Supplement.
(a) AS 1548 carbon-manganese steel plate— designstrength values shall be as listed in Table S3.3.1(i).
(b) Other materials to Standards Australiaspecifications— for other steels and non-ferrousmaterials to Standards Australia specifications,design strength values are under consideration, butthe design strength may be determined on the basisof Appendix SA or may be taken equal to thevalues of Table 3.3.1.
(c) Materials to BSI and ASTM specifications— designstrength values shall be as specified inTable S3.3.1(ii).
TABLE S3.3.1(i)DESIGN STRENGTH CARBON-MANGANESE STEEL PLATE TO AS 1548
Materialtype
StandardNo
Grade(see Note)
GroupNo
ThicknessDesign strength (f), MPa
Temperature, °Cmm 50 100 150 200 250 300 325 350 375 400
C-Mn AS 1548 5-490N,T A2>16>40>80
≤≤≤≤
164080
150
209209209209
194194194194
179179179179
168168168168
150150150150
138138138138
134134134134
130130130130
126126126126
122122122122
7-430R, N, T A1>16>40>80
≤≤≤≤
164080
150
183183180167
169167165151
154151148135
139138135130
124124124124
110110110110
108108108108
105105105105
102102102102
99999999
7-460R, N, T A1>16>40>80
≤≤≤≤
164080
150
196196183177
175173166156
154151148135
139138135130
124124124124
110110110110
108108108108
105105105105
102102102102
99999999
7-490R, N, T A2>16>40>80
≤≤≤≤
164080
150
209207200187
187184180172
165162160156
150148146142
132132132132
120120120120
117117117117
114114114114
111111111111
108108108108
5-490NH, TH A2>16>40>80
≤≤≤≤
164080
150
209209209209
200200200200
191191191191
179179179179
160160160160
147147147147
143143143143
139139139139
133133133133
127127127127
7-430RH, NH, TH A1>16>40>80
≤≤≤≤
164080
150
183183180167
174172168156
164161157144
148147144139
132132132132
117117117117
114114114114
112112112112
108108108108
105105105105
7-460RH, NH, TH A1>16>40>80
≤≤≤≤
164080
150
196196183177
180178170160
164161157144
148147144139
132132132132
117117117117
114114114114
112112112112
108108108108
105105105105
7-490RH, NH, TH A2>16>40>80
≤≤≤≤
164080
150
209207200187
192190186177
176173171167
160157156152
141141141141
128128128128
125125125125
121121121121
118118118118
115115115115
NOTE: For a designation AS 1548 steel plate, the following criteria are to apply:(a) A designation Type 5 plate shall not be used where the plate is to be in the non-normalized condition in the completed vessel.(b) For A designation Type 7 plate which is to be in the non-normalized condition in the completed vessel, the design tensile strength values listed
for the otherwise equivalent R designation Type 7 plate may be used, provided that the test certificate for each plate is endorsed by the platemanufacturer to show that the plate complies with both A and R designation requirements.
(c) For A designation plate which is to be in the normalized conditions in the completed vessel, the design tensile strength values listed for theotherwise equivalent N designation plate may be used.
TABLE S3.3.1(ii)DESIGN STRENGTH — MATERIALS TO BS AND ASTM SPECIFICATIONS
Material specification Design strength (f)BS specifications—Material types and grades permitted in BS 5500for Category 1 vessels
Values equal to the ‘Design Strength Values’specified in BS 5500
ASTM specifications—Material types and grades specified inANSI/ASME BPV-VIII-2
Values equal to the ‘Design Stress IntensityValues’ specified in ANSI/ASME BPV-VIII-2
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S3.5 WELDED, RIVETED AND BRAZED JOINTS.Clause 3.5 applies, with the following additions andmodifications.S3.5.1 Welded joints.Clause 3.5.1 applies with thefollowing additions and modifications to particularClauses:S3.5.1.7Welded joint efficiency.Clause 3.5.1.7 appliesexcept that for welded main longitudinal andcircumferential joints of Class 2HA and Class 2HBvessels complying with the requirements of thisSupplement, a joint efficiency of 1.0 may be used.Only joints having an efficiency of 1.0 shall be used forwelded main joints.S3.5.1.8 Butt-welding between plates of unequalthickness. Clause 3.5.1.8 does not apply to thisSupplement and the following shall be substituted:If two plates are to be welded by a butt joint and differin thickness by more than 25 percent of the thinner plate,or by more than 3 mm, the thicker plate shall be reducedas shown in Figure 3.5.1.8. In all such cases, the edge ofthe thicker plate shall be trimmed to a smooth taperextending for a distance of at least four times the offsetbetween the abutting surfaces so that the adjoining edgeswill be approximately the same thickness. The length ofthe required taper may include the width of the weld.The maximum thickness through the weld shall be asgiven in Table 3.1 of AS 4037—1992.For attachment of ends to shells of differing thickness,see Clause 3.12.6.S3.5.2 Riveted joints.Not permitted.S3.5.3 Brazed joins.Not permitted.
S3.7 THIN-WALLED CYLINDRICAL ANDSPHERICAL SHELLS SUBJECT TO INTERNALPRESSURE AND COMBINED LOADINGS.Clause 3.7 applies, with the following addition:For components of simple vessels not subject toadditional external or internal loads and for whichdetailed fatigue analysis is not required byClauses S3.1.5.4 to S3.1.5.7, the minimum thickness ofcylindrical and spherical shells shall be calculated fromthe following equations:For cylindrical shells —
t = . . . . . . . . . . . . . . . . . . S3.7(1)
For spherical shells —
t = . . . . . . . . . . . . . . . . . . S3.7(2)
Vessels or vessel components designed to resistadditional loads or requiring detailed fatigue analysisshall be the subject of a detailed stress investigation.
S3.8 THICK-WALLED CYLINDRICAL ANDSPHERICAL SHELLS SUBJECT TO INTERNALPRESSURE. Clause 3.8 applies, with the followingadditions:For components of simple vessels not subject toadditional external or internal loads and for whichdetailed fatigue analysis is not required byClauses S3.1.5.4 to S3.1.5.7, the minimum thicknessshall be calculated from equations given in Clause S3.7,except that whereP > 0.4f the following equations maybe used:
For cylindrical shells —
P = f loge . . . . . . . . . . . . . S3.8(1)
For spherical shells —
P = 2f loge . . . . . . . . . . . . S3.8(2)
loge is the natural logarithm, i.e. to the base e.Vessels or vessel components designed to resistadditional loads or requiring detailed fatigue analysisshall be the subject of a detailed stress investigation.
S3.9 CYLINDRICAL AND SPHERICAL SHELLSSUBJECT TO EXTERNAL PRESSURE. Clause 3.9applies in its entirety, including design strengths.
S3.10 CONICAL ENDS ANDREDUCERS SUBJECTTO INTERNAL PRESSURE. Clause 3.10 applies, withthe following additions:For simple vessels not subject to additional external orinternal loads and for which detailed fatigue analysis isnot required by Clauses S3.1.5.4 to S3.1.5.7, theminimum thickness of conical ends and reducers subjectto internal pressure shall be determined in accordancewith Clause 3.10, but with values for design strengthfrom Table S3.3.1.Vessels or vessel components designed to resistadditional loads or requiring detailed fatigue analysisshall be the subject of a detailed stress investigation.
S3.11 CONICAL ENDS ANDREDUCERS SUBJECTTO EXTERNAL PRESSURE. Clause 3.11 applies inits entirety, including design strengths.
S3.12 DISHED ENDS SUBJECT TO INTERNALPRESSURE. Clause 3.12 applies with the followingaddition and modifications:For simple vessels or vessel components not subject toloads additional to the loads due to internal pressure, notrequiring detailed fatigue analysis by Clauses S3.1.5.4 toS3.1.5.7 and of shapes covered in Clause S3.12.5, theminimum calculated thickness of dished ends shall bedetermined from Clause S3.12.5 in lieu of therequirements in Clause 3.12.5.For other vessels or vessel components, dished ends shallbe the subject of a detailed stress analysis.
NOTE: The design method given in Clause S3.12.5 and the methodsfor the design of ends in other relevant Standards which form partof the SAA Boiler Code are currently under review with theobjective of having a consistent basis for the design of ends. In themeantime, designers should be aware that there are differencesbetween these Standards.
S3.12.5 Thickness of ends.(a) Torispherical ends. The minimum calculated
thickness of torispherical ends shall be determinedby Equation S3.12.5(1) or Equation S3.12.5(2) asfollows:
(i) For ≥ 0.002 and ≤ 0.08 —
t = R × 10G . . . . . . . . . . . . . . S3.12.5(1)
(ii) For > 0.08 —
t = [e(P/f) - 1] . . . . . . . . S3.12.5(2)
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where
G = A + B log10(P/f) + C[log10(P/f)] 2
A = −0.5480 − 1.9771(r/D) +12.5655(r/D)2
B = 0.6630− 2.2471(r/D) +15.6830(r/D)2
C = 6.1891× 10−5 − 0.9731(r/D) +4.3469(r/D)2
f = design strength at the designtemperature (see Table S3.3.1),in megapascals
e = base of natural log
≈ 2.7183
For other notation, see Clause 3.12.1.
The inside crown radius shall be not greater thanthe outside diameter (Do) of the end.
The inside knuckle radius shall be not less than6 percent of the outside diameter (Do) or 3 timesthe end thickness.
(b) Ellipsoidal ends. The minimum calculated
thickness of 2:1 ellipsoidal ( = 4) ends shall
be determined as follows:
(i) For 0.002≤ ≤ 0.08 —
t = D × 10H . . . . . . . . . . S3.12.5(3)
Where
H = −0.35237 + 0.90748 log10 −
(ii) For > 0.08 —
by Equation S3.12.5(2)
(c) Hemispherical ends.The minimum calculatedthickness for hemispherical ends shall complywith Clause S3.7 or S3.8 as appropriate.
S3.13 DISHED ENDS SUBJECT TO EXTERNALPRESSURE. Clause 3.13 applies in its entirety,including design strengths.
S3.14 DISHED ENDS — BOLTED SPHERICALTYPE. Clause 3.14 applies, with the followingaddition:
For simple vessels not subject to additional externalor internal loads and for which detailed fatigueanalysis is not required by Clauses S3.1.5.4 toS3.1.5.7, the minimum thickness of dished ends ofthe bolted spherical type shall be determined inaccordance with Clause 3.4, but with values fordesign strength from Table S3.3.1.
Vessels or vessel components designed to resistadditional loads or requiring detailed fatigue analysisshall be the subject of a detailed stress investigation.
S3.15 UNSTAYED FLAT ENDS AND COVERS.Clause 3.15 applies, with the following addition:
The thickness of unstayed flat ends shall bedetermined in accordance with Clause 3.15, but withvalues for design strength from Table S3.3.1. Wherethe ends are attached by welding, the welds shall beof the full penetration type.
Ends designed to resist additional loads or requiringdetailed fatigue analysis shall be the subject of adetailed stress investigation.
S3.15.5Internally fitted doors.Clause 3.15.5 applies,except that design strength from Table S3.3.1 may beused.
S3.16 STAYED FLAT ENDS AND SURFACES.Clause 3.16 applies, with the following addition:
Stayed flat ends are frequently subject to internalforce and deflection and therefore require a detailedanalysis for assessment of the working stresses. Forproven simple vessels that are not subject to largetemperature differentials, stayed ends may bedesigned in accordance with Clause 3.16 with valuesfor design strength from Table S3.3.1.
S3.17 FLAT TUBEPLATES. Clause 3.17 applies,with the following exceptions:
The design of flat tubeplates shall be in accordancewith Clause 3.17, except that the design strength fromTable S3.3.1 may be used in conjunction withAS 3857. When adopting the TEMA method, thedesign strength from Table 3.3.1 shall be used.
S3.18 OPENINGS AND REINFORCEMENT.Clause 3.18 excluding Clause 3.18.6 applies with thefollowing addition and modification.
Design strengths from Table S3.3.1 may be used.
Departures from the above ‘reinforcement’requirements are permitted if supported by theoreticalor experimental investigation or where sufficientpractical experience has demonstrated the adequacyof an alternative design.
S3.18.6 Unreinforced openings.Clause 3.18.6 doesnot apply and the following shall be substituted:
Circular openings are not required to havereinforcement other than that inherent in theconstruction where all of the following conditionsapply as applicable:
(a) A single opening shall have a diameterd(see Clause 3.18.2) not exceeding 0.2 (RmT1), orif there are two or more openings within anycircle of diameter 2.5 (RmT1) then the sum of thediameters of such unreinforced openings shallnot exceed 0.25 (RmT1), whereRm is the meanradius of the shell or end at the location of theopenings.
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(b) No two unreinforced openings shall have theircentres closer to each other, measured on the insideof the vessel wall, than 1.5 times the sum of theirdiameters.
(c) No unreinforced opening shall have its centre closerthan 2.5 (RmT1) to the edge of a locally stressedarea in the shell or end; locally stressed area meansany area in the shell or end where the primary localmembrane stress exceeds 1.1f, but excluding thoseareas where such primary local membrane stress isdue to an unreinforced opening.
S3.19 CONNECTIONS AND BRANCHES.Clause 3.19 applies with the following addition:
Design strengths from Table S3.3.1 may be used.
Welded branches shall be attached by full penetrationwelds unless it can be shown by theory, experiment orrecords of past experience, that alternative types ofconnections are satisfactory.
S3.21 BOLTED FLANGED CONNECTIONS.Clause 3.21 applies with the following addition:
Design strengths for flange bolting shall comply withClause S3.3.1.3.
For components of bolted flanged connections other thanbolting and gaskets, design strengths as listed inTable 3.3.1 shall be used unless a detailed stress analysisof the bolted joint is made and this analysis verifies theacceptability of higher design strengths.
S3.22 PIPES AND TUBES.Clause 3.22 applies, withthe following addition:
Where appropriate to the type of vessel covered by thisSupplement, Clause 3.22 applies. Where minimum
thicknesses are determined by calculation, designstrengths from Table S3.3.1 may be used.
S3.23 JACKETED CONSTRUCTION. Clause 3.23applies, with the following addition:
NOTE: Jacketed vessels can give rise to high local stresses due torestrained movements of various vessel components, i.e. at jacketclosures.
In areas of high local stress concentration a detailedstress analysis shall be required except that in simplecases and where the temperature differential is low orwhere there is good evidence of satisfactory pastexperience, Clause 3.23 and design strengths given inTable S3.3.1 may be used.
S3.24 VESSEL SUPPORTS.Clause 3.24 applies, withthe following additions and modifications:
Design strengths from Table S3.3.1 may be used.NOTE: Clause 3.24 should adequately cover support design for mostvessels; however, in exceptional cases, e.g. very large, heavy vessels,or operations with large temperature differentials, the designer maybe required to carry out a detailed stress analysis.
S3.25 ATTACHED STRUCTURES ANDEQUIPMENT. Clause 3.25 applies, with the followingaddition:
The designer shall assess the severity of any loadsimposed by an attachment. If such loads are significant,a detailed stress analysis shall be carried out to calculateactual stresses.
S3.26 TRANSPORTABLE VESSELS. Clause 3.26does not apply to this Supplement and the followingshall be substituted:
Not permitted.
SECTION S4. CONSTRUCTION
Section 4 of AS 1210 shall apply.
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SECTION S5. TESTING AND QUALIFICATIONS
Section 5 of AS 1210 shall apply, with the followingadditions and modifications to particular Clauses:
S5.10 HYDROSTATIC TESTS. Clause 5.10 applies,with the following additions and modifications toparticular Clauses:
S5.10.2.1 Single-wall vessels designed for internalpressure. Clause 5.10.2.1 does not apply to thisSupplement and the following shall be substituted:
For single-wall vessels designed for internal pressure, thehydrostatic test pressurePh shall be at least thatdetermined by the following equation:
Ph = 1.25 . . . . . . . . . . . S5.10.2
where
Ph = hydrostatic test pressure, in megapascals
P = design pressure ofvessel, inmegapascals
fh = design strength at test temperature (fromTable S3.3.1), in megapascals
f = design strength at design temperature(from Table S3.3.1), in megapascals
The expression with the brackets of Equation S5.10.2shall be termed the ‘equivalent design pressure’, i.e. thedesign pressure of the weakest part of the vessel in the‘new and cold’ condition. Where necessary, the‘equivalent design pressure’ shall take into accountdifferences in design conditions which may be specifiedfor different sections of the compartment of the vesselunder test.
This test pressure shall include any static head actingduring the test on the part under consideration. Allloadings including static head which may exist during thetest and which differ from those specified for the designconditions shall be given special consideration.
The test pressure should be as close as practicable to thepressure determined in accordance wi thEquation S5.10.2. If higher pressures are used, eitherintentionally or accidentally, the vessel may becomevisibly and permanentlydistorted beyond the dimensionallimits specified in this Supplement, it may leak atmechanical joints, or cracking may occur. In such cases,the vessel is liable to rejection by the Inspector.
The test pressure shall be such that the generalmembrane stress in any part of the vessel during test willnot exceed 90 percent of the specified minimum yield orproof stress of the material at the test temperature.
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S5.11 PNEUMATIC TESTS.Clause 5.11 applies, withthe following additions and modifications to particularClauses:
S5.11.3 Test pressure.Clause 5.11.4 does not apply tothis Supplement and the following shall be substituted:
Unless otherwise approved, the test pressure shall be1.15 times the equivalent design pressure or pressuredifferential, as required by Clause S5.10.2.1,Clause 5.10.2.2, or Clause 5.10.2.3.
S5.11.4 Application of pressure.AS 4037 appliesexcept where modified by the following:
The pressure shall be gradually increased to not morethan 50 percent of the required test pressure. Thereafter,the test pressure shall be increased slowly and steadily,pausing at increments of approximately 10 percent orless of the final test pressure until the required testpressure is reached. The pressure shall then be reducedto a value equal to the equivalent design pressure andheld at this pressure for sufficient time to permit visualinspection of the vessel.
S5.11.5 Combined hydrostat ic/pneumatictest AS 4037 applies except where modified by thefollowing:
The liquid level is set so that the maximum stressincluding the stress produced by the pneumatic pressureat any point in the vessel (usually near the bottom or atthe support attachments) does not exceed 90 percent ofthe specified minimum yield or proof stress of thematerial at the test temperature.
S5.12 EXPERIMENTAL STRESS ANALYSIS.Clause 5.12 does not apply to this Supplement and thefollowing shall be substituted:
S5.12.1 Application. The critical stresses in parts forwhich theoretical stress analysis is inadequate or forwhich design rules are not available shall besubstantiated by experimental stress analysis.
The extent of experimental stress analysis performedshall be sufficient to determine the critical stresses forwhich design values are not available. Where possible,combined analytical and experimental methods shall beused to distinguish between primary, secondary and localstresses.
Where experimental stress analysis is used, the generalprinciples, design rules, construction, testing andinspection requirements of this Supplement shall becomplied with.
S5.12.2 Types of test.Permissible types of test for thedetermination of critical stresses are strain measurementtest and photoelastic tests. Fatigue tests may be used toevaluate the adequacy of a part for cyclic loading.(See Paragraph SC4, Appendix SC.)
S5.12.3 General requirements.
S5.12.3.1Hydrostatic testing.The general requirementsfor hydrostatic tests in Clause S5.10, which are relevantshall apply.
S5.12.3.2Prior pressure.The vessel or vessel part forwhich the design or calculation pressure is to beestablished shall not have been previously subjected to apressure greater than the equivalent design pressure. (SeeClause S5.10.2.1.)
S5.12.3.3Safety.Serious consideration shall be given tothe safety of all personnel prior to the conducting of anytests. Particular attention should be paid to theelimination of any air pocket in the vessel.
S5.12.3.4Witnessing of tests.Testing shall be witnessedby an Inspector approved by the Inspecting Authority.Test results shall be recorded.
S5.12.3.5Duplicate vessels or vessel parts.Where thecritical stresses of a vessel or vessel part have beensubstantiated by experimental stress analysis, duplicateparts of the same materials, design and construction neednot be re-tested under Clause S5.12 but shall be given ahydrostatic test in accordance with Clause S5.10 or apneumatic test in accordance with Clause S5.11. Thedimensions, including minimum thickness, of the vesselor vessel part tested shall not vary significantly fromthose actually used.
S5.12.3.6 Retests.A retest shall be allowed on aduplicate vessel or vessel part if errors or irregularitiesare obvious in the test results.
S5.12.4 Strain gauge tests.
S5.12.4.1 Strain gauges.Principal strains shall bemeasured by means of a device (or combination ofdevices) having an accuracy of±7 percent and asensitivity of better than 5 percent. The range of thedevice should be approximately three times the yieldstrain of the material under test.
S5.12.4.2Mounting of strain gauges.Strain gauges shallbe mounted on the unpressurized vessel before the test,and after any pressure cycling.
The strain gauges shall be attached in a manner whichwill assure accurate measurement of strain.
The positioning of strain gauges shall enable strains to bemeasured in the direction of the maximum stress in themost highly stressed areas. This may require the use ofa number of strain gauges which should be located onboth the inside and outside surfaces. Application of abrittle coating may be required, by the InspectingAuthority, to verify that the strain gauges are located inthe high stress areas.
The vessel may be cycled several times to 50 percent ofthe equivalent design pressure in order to relieve initialresidual stresses.
S5.12.4.3 Application of pressure.The hydrostaticpressure in the vessel or vessel part shall be steadilyincreased until approximately 50 percent of theequivalent design pressure is reached. Thereafter, the testpressure shall be steadily increased, pausing atincrements of approximately 10 percent or less of theequivalent design pressure, until the pressure required bythe test procedure is reached.
Any observations or measurement shall be made whilethe pressure is maintained at a constant value.
S5.12.4.4 Strain and pressure readings.After eachincrement of pressure has been applied, readings of strainand pressure shall be taken and recorded. After anypressure increment where there is an indication of anincrease of strain proportionately greater than theprevious increments, the pressure shall be released tozero to permit determination of any permanent strain.Whenever the pressure is released, any permanent strainat each gauge shall be determined. After such readings
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have been taken, the pressure shall be reapplied as oftenas necessary, as specified in Clause S5.12.4.3.
S5.12.4.5Plotting of strain.Two curves of strainvs testpressure shall be plotted for each gauge as the testprogresses, one showing total strain under pressure, andthe other showing total strain as the pressure is removed.
S5.12.4.6Maximum test pressure.The test may bediscontinued when either —
(a) the test pressure reaches the value which will justifythe desired design (or calculation) pressure; or
(b) the measured strain becomes equivalent to 1.25times the expected permissible design strain in thevessel component under investigation (thepermissible design strain is deduced from theappropriate stress category permitted in the vesselcomponent under investigation).
S5.12.4.7Determination of actual yield (or proof) stress.The value reported for the yield or proof stress shall bethe arithmetic mean of four separate tests carried out onfour separate test specimens cut from the vesselfollowing the completion of the pressure test.
The specimens shall be cut from a location where thestress during the test has not exceeded the yield stress,and shall be representative of the material wheremaximum stress occurs.
Where excess stock from the same piece of wroughtmaterial is available and has been given the same heattreatment as the pressure part, the test specimens may becut from this excess stock.
Specimens shall not be removed by thermal-cutting orany other method involving sufficient heat to affect theproperties of the specimen.
S5.12.4.8Interpretation of results.In the evaluation ofstresses from strain gauge data, the calculations shall beperformed under the assumption that the material iselastic. The elastic constants used in the evaluation ofexperimental data shall be those applicable to thematerial at the test temperature.
S5.12.4.9Use of models for strain measurement.Straingauge data may be obtained from the actual vessel orfrom a vessel model. The material of the model need notbe the same as the material of the vessel, but thematerial of the model shall have an elastic moduluswhich is either known or has been measured at the testconditions. The requirements of dimensional similitudeshall be met as closely as possible.
S5.12.5 Photoelastic tests.Either two-dimensional orthree-dimensional techniques may be used provided thatthe model represents the structural effects of the loading.
S5.13 LEAK TEST. Clause 5.13 applies, with thefollowing modifications:
S5.13.4 Preliminary leak test.Clause S5.13.4 appliesexcept where modified by the following:
A preliminary leak test may be applied to any vesselwithout observing the requirements applying to highpressure pneumatic testing (see Clause S5.11), providedthat the test pressure does not exceed 10 percent of thedesign pressure or 35 kPa, whichever is the lesser.
S5.19 NON-DESTRUCTIVE EXAMINATION OFFORGINGS.
S5.19.1 Type and extent.All forgings, as required byClause S2.8, shall be subject to ultrasonic examinationin accordance with this Clause (5.19).
S5.19.2 Ultrasonic examination procedure. Theprocedure for ultrasonic examination shall be as follows:
(a) The preparation of forgings and the method andprocedure for ultrasonic examination shall complywith AS 1065.1, or other approved Standards asappropriate.
(b) The level of sensitivity used shall be such that theexamination is capable of detecting the artificialdefects in a reference block or specimen of a typesuitable for the particular application. The referencespecimen shall have the same nominal thickness,composition, and steel grouping as the forging to beexamined in order to have substantially the samestructure.
(c) All conditions such as surface finish, ultrasonicfrequency, instrument settings, type of transducer,and couplant used during calibration shall beduplicated during the actual examination.
(d) In so far as practicable, all forgings shall beexamined by the normal beam method from twodirections approximately at right angles. Rings,flanges, and other straight hollow forgings shall beexamined by the angle beam method from onecircumferential surface and from one face or surfacenormal to the axis. Disc forgings shall be examinedfrom one flat side and from the circumferentialsurface. Forgings requiring angle beam examinationshall be examined in the circumferential direction,unless wall thickness or geometric configuration ofthe forgings make angle beam examinationimpracticable.
The entire volume of material shall be examinedultrasonically at some stage of manufacture,preferably after final heat treatment. If contours ofthe forging preclude complete ultrasonicexamination after final heat treatment, the maximumpermissible volume shall be examined prior to finalheat treatment.
S5.19.3 Ultrasonic acceptance standards.Forgings foruse as critical vessel components, e.g. ends, shall nothave any of the following discontinuities:
(a) For normal beam method.
(i) One or more discontinuities which produceindications accompanied by a complete loss ofback reflection not associated with orattributable to the geometric configuration.
(ii) One or more indications with amplitudesexceeding adjacent back reflections.
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(iii) One or more discontinuities which producetravelling indications accompanied by reducedback reflections. (A travelling indication isdefined as an indication which displays sweepmovement of the oscilloscope screen atrelatively constant amplitude as the transduceris moved.)
(b) For angle beam method.(i) One or more discontinuities which produce
indications exceeding in amplitude theindication from the calibration notch.
(ii) Indications having an amplitude exceeding 50percent of the calibration notch amplitude.
(iii) Clusters of indications located in a small areaof the forging with amplitude less than50 percent of the calibration notch amplitude.
(A cluster of indications is defined as three or moreindications exceeding 10 percent of the standardcalibration notch amplitude and located in any volumeapproximating a 50-millimetre or smaller cube.)
Forgings for use as non-critical vessel components, e.g.baffles, supports, should comply with the requirements ofthis Clause.
NOTE: Where a discontinuity is at the limiting conditions specifiedin Clause S5.19.3, acceptance of that forging is subject to agreementbetween the parties concerned.
S5.19.4 Interpretation of ultrasonic indication.Additional non-destructive examination procedures ortrepanning may be employed to resolve questions ofinterpretation of ultrasonic indications.
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SECTION S6. INSPECTION
Section 6 of AS 1210 shall apply.
SECTION S7. MARKING AND REPORTS
Section 7 of AS 1210 shall apply with the following modification:
S7.1 MARKING REQUIRED. Clause 7.1 shall apply with the exception that item (g) shallbe replaced by the following:
(g) The designation number (see Clause S1.12).
SECTION S8. PROTECTIVE DEVICES AND OTHER FITTINGS
Section 8 of AS 1210 shall apply.
SECTION S9. PROVISIONS FOR DESPATCH
Section 9 of AS 1210 shall apply.
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APPENDIX A
BASIS OF DESIGN STRENGTH (f)
(This Appendix forms an integral part of this Supplement.)
Appendix A of AS 1210 does not apply to this Supplement and the following shall besubstituted:
SA1 MATERIALS TO SAA SPECIFICATIONS.
SA1.1 Introduction. The design strengths given in Table S3.3.1 (for other than bolting) arebased on criteria given in Table SA1.1 using mechanical properties of the material asindicated. These values do not include any allowance for casting quality factor or otherfactors applicable as this is provided in the appropriate Clauses of this Supplement.
In some instances the design strength values listed in Table S3.3.1 vary from the valuesderived from the above criteria. This occurs where satisfactory evidence of safe use of thehigher values has been established.
SA1.2 Materials.The basis given herein is limited to materials having adequate qualitiesfor plastic deformation at stress concentration points in connection with the servicetemperature and the design strengths considered. This requirement should be met by all thesteels listed in Table S3.3.1.
SA2 MATERIALS TO BRITISH SPECIFICATIONS. The basis for the ‘design strengthvalues’ listed in BS 5500 is given in Appendix K of that Standard.
SA3 MATERIALS TO AMERICAN SPECIFICATIONS. The basis for the ‘design stressintensity values’ listed in ANSI/ASME BPV-VIII-2 is given in Appendix 1 of that Standard.
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TABLE SA1.1FACTORS USED FOR DETERMINING DESIGN STRENGTH VALUES
FOR MATERIALS TO SAA SPECIFICATIONS EXCLUDING BOLTING MATERIAL(Design strength is obtained by dividing specified value by the given factor)
Material type and designtemperature
Materialverification
Specified minimumtensile strength at room
temperature(see Note 1)
Specified minimum yield(or proof) stress at room
temperature(see Notes 1 and 2)
Specified minimum yied(or proof) stress at design
temperature(see Notes 2 and 3)
CARBON, CARBON-MANGANESE AND LOWALLOY STEELS
(a) Design temperature≤50°C
Verified or hot tested 2.35 1.5 —
Not verified norhot tested
2.35 1.5 —
(b) Design temperature>50°C and <150°C
See Note 4 — — —
(c) Design temperature≥150°C
Verified orhot tested
2.35 — 1.5
Not verified norhot tested
2.35 — 1.6
HIGH ALLOY STEELS
(a) Design temperature≤50°C
Verified orhot tested
2.5 1.5 —
Not verified norhot tested
2.5 1.5 —
(b) Design temperature>50°C and <150°C
See Note 4 — — —
(c) Design temperature≥150°C
Verified orhot tested
2.5 — 1.35
Not verifiednor hot tested
2.5 — 1.45
NON-FERROUS METALSAND ALLOYS
(a) Design temperature≤50°C
Verified orhot tested
3 1.5 —
Not verifiednor hot tested
3 1.5 —
(b) Design temperature>50°C and <100°C
See Note 4 — — —
(c) Design temperature≥100°C
Verified orhot tested
3 1.5 1.5
Not verifiednor hot tested
3 — 1.7
NOTES:1. Tested in accordance with AS 1391 or ISO 6892.2. Proof stress determined at—
0.2 percent offset value for ferritic steels.1 percent offset value for austenitic steels.
3. Tested in accordance with BS 3688:Part 1 or ISO/R 783.4. Strength values are based on linear interpolation between values obtained from (a) and (c).
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APPENDIX SB
Appendix B of AS 1210 shall apply.
APPENDIX SC
PRACTICE TO AVOID FATIGUE CRACKING
(This Appendix forms an integral part of this Supplement.)
Appendix C of AS 1210 does not apply to this Supplement and the following shall besubstituted:
SC1 ANALYSIS FOR CYCLIC OPERATION.
SC1.1 General.Unless the specified operation of the vessel meets all of the conditions ofClauses S3.1.5.4 to S3.1.5.7, a detailed analysis for cyclic operation is required.
This Appendix gives rules for determining the suitability of a vessel or vessel componentfor specified operating conditions involving cyclic application of loads or thermal conditions.
SC1.2 Allowable amplitude of alternating stresses.The conditions and procedures ofClauses S3.1.5.4 to S3.1.5.7 and Paragraph SC2 are based on a comparison of peak stresseswith strain-cycling fatigue data. The strain-cycling fatigue data are represented by the designfatigue strength curves of Figures SC1.2.1 and SC1.2.2. These curves show the allowableamplitude (Sa) of the following stress component (50 percent of the alternating stress range)plotted against the number of cycles. This stress amplitude is calculated on the assumptionof elastic behaviour, and hence, has the dimensions of stress but it does not represent a realstress when the elastic range is exceeded. The fatigue curves are obtained from uniaxialstrain strain-cycling data in which the imposed strains have been multiplied by the elasticmodulus and a design margin has been provided, so as to make the calculated stressintensity and amplitude and the allowable stress amplitude directly comparable. The curveshave been adjusted where necessary to include the maximum effects of mean stress, whichis the condition where the stress fluctuates about a mean value other than zero. As aconsequence of this procedure, it is essential that the requirements of this Supplement becomplied with at all times, with transient stresses included, and that the calculated value ofthe alternating stress intensity be proportional to the actual strain amplitude. To evaluate theeffect of alternating stresses at varying amplitudes, a linear damage relation is assumed inParagraph SC2.2.5.
SC1.3 Loadings to be considered.The loadings to be considered shall include those loadsthat are due to testing of the vessel where such testing is in addition to that required by thisSupplement.
SC2 DESIGN FOR CYCLIC LOADINGS.
SC2.1 Adequacy of design for cyclic loading.The ability of the vessel to withstand thespecified cyclic operation without fatigue failure shall be determined in accordance with thisParagraph (SC2). The determination shall be made on the basis of the stresses at a point ofthe vessel and the allowable stress cycles shall be adequate for the specified operation atevery point. Only the stresses due to the specified cycle of operation need be considered;stresses produced by any load or thermal condition which does not vary during the cycleneed not be considered, since they are mean stresses and the maximum possible effect ofmean stress is included in the fatigue design curves.
SC2.2 Design procedure.
SC2.2.1Where principal stress direction does not change.For any case in which thedirections of the principal stresses at the point being considered do not change during thecycle, the alternating stress intensity shall be determined by the following steps:
(a) Principle stresses.Consider the values of the three principal stresses at the point versustime for the complete stress cycle, taking into account both the gross and localstructural discontinuities and the thermal effects which vary during the cycle. These aredesignated asσ1, σ2 andσ3 for later identification.
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NOTES:1. Rm = specified minimum tensile strength at room temperature.2. Interpolate forRm for 550 MPa to 790 MPa.
FIGURE SC1.2.1 DESIGN FATIGUE CURVES FOR CARBON, LOW ALLOY,SERIES 4XX HIGH ALLOY STEELS AND HIGH TENSILE STEELS FOR
TEMPERATURES ≤375°C
FIGURE SC1.2.2 DESIGN FATIGUE CURVE FOR SERIES 3XX HIGHALLOY STEELS, NICKEL-CHROMIUM IRON ALLOY, NICKEL-IRON-CHROMIUM
ALLOY, AND NICKEL-COPPER ALLOY FOR TEMPERATURES ≤425°C
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(b) Stress differences.Determine the stress differencesS12 = σ1 - σ2, S23 = σ2 - σ3, S31 = σ3 - σ1
versus time for the complete cycle. In what follows, the symbolSij is used to representany one of these three stress differences.
(c) Alternating stress intensity.Determine the extremes of the range through which eachstress difference,Sij fluctuates and find the absolute magnitude of this range for eachSij . Call this magnitudeSrij and letSaltij = 0.5Srij. The alternating stress intensitySalt isthe largest of the values ofSaltij.
SC2.2.2Where principal stress direction changes.For any case in which the directions ofthe principal stresses at the point being considered changes during the stress cycle, it isnecessary to use the following more general procedure:(a) Consider the values of the six stress componentsσ t, σl, σr, τlt, τ lr, τrt, versus time for
the complete stress cycle, taking into account both the gross and local structuraldiscontinuities and the thermal effects which vary during the cycle.
(b) Choose a point in time when the conditions are one of the extremes for the cycle(either maximum or minimum, algebraically) and identify the stress components at thistime by the subscript i. In most cases it will be possible to choose at least one timeduring the cycle when the conditions are known to be extreme. In some cases it maybe necessary to try different points in time to find the one which results in the largestvalue of alternating stress intensity.
(c) Subtract each of the six stress componentsσ ti, σli , etc from the corresponding stresscomponentsσt, σl, etc at each point in time during the cycle and call the resultingcomponentsσ t’, σl’, etc.
(d) At each point in time during the cycle, calculate the principal stressesσ 1’, σ2’, σ3’derived from the six stress components,σt’, σl’, etc. Note that the directions of theprincipal stresses may change during the cycle but each principal stress retains itsidentity as it rotates.
(e) Determine the stress differencesS12′ = σ1′ – σ2′, S23′ = σ2′ – σ3′, S31′ = σ3′ – σ1′versus time for the complete cycle and find the largest absolute magnitude of any stressdifference at any time. The alternating stress intensitySalt is 50 percent of thismagnitude.
SC2.2.3Design fatigue curves.The applicable fatigue design curves for some of thematerials permitted by this Supplement are contained in Figures SC1.2.1 and SC1.2.2.SC2.2.4Use of design fatigue curves.The alternating stress intensitySalt as determined byParagraph SC2.2.1 and Paragraph SC2.2.2 shall be multiplied by the ratio of the modulusof elasticity given on the design fatigue curve to the value used in the analysis. Theapplicable design stress shall be entered at this value on the ordinate axis and thecorresponding number of cycles found on the axis of abscissa. If the operational cycle beingconsidered is the only one which produces significant fluctuating stresses, this is theallowable number of cycles. When there are two or more types of stress cycle whichproduce significant stresses, their cumulative effect shall be evaluated in accordance withParagraph SC2.2.5.SC2.2.5Cumulative damage.Cumulative damage shall be evaluated in accordance with thefollowing:(a) Designate the specified number of times each type of stress cycle of types, 1, 2, 3, etc,
will be repeated during the life of the vessel asn1, n2, n3, etc, respectively. In thedetermination ofn1, n2, n3, etc, consideration shall be given to the superposition ofcycles of various origins which produce a total stress-difference range greater than thestress-difference ranges of the individual cycles.
(b) For each type of stress cycle, determine the alternating stress intensitySalt inaccordance with the procedures of Paragraph SC2.2.1 or Paragraph SC2.2.2. Definethese quantitiesSalt1, Salt2, Salt3, etc.
(c) For each value,Salt1, Salt2, Salt3, etc, use the applicable design fatigue curve to determinethe maximum of repetitionsN1, N2, N3, etc, respectively which would be allowable ifthis type of cycle were the only one acting.
(d) For each type of stress cycle, calculate the usage factors,U1, U2, U3, etc from —
U1 = , U2 = , etc.
(e) Calculate the cumulate usage factorU, from U = U 1 + U2 + U3 + .. etc.(f) The cumulative usage factorU shall not exceed 1.0.
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SC2.2.6Local structural discontinuities.The effects of local structural discontinuities shallbe evaluated by the use of theoretical stress concentration factors for all conditions, exceptthat experimentally determined fatigue strength reduction factors may be used whendetermined in accordance with Paragraph SC5.SC2.2.7Fillet welds.Fillet welds shall not be used in vessels for joints of categories A, B,C, and D (see Figure 3.5.1.1) except as permitted for joints of category C for slip-on flangesand for joints of category D as permitted in Clause S3.19. Fillet welds may be used forattachments to pressure vessels using one-half of the stress limit given in Paragraph SH2.4.3(a) to (d), Appendix SH for primary and secondary stresses.Evaluation for cyclic loading shall be made in accordance with Appendix SC using a fatiguestrength reduction factor of 4 and shall include consideration of temperature differencesbetween the vessel and the attachment and expansion or contraction of the vessel caused byinternal or external pressure.
SC3 FATIGUE ANALYSIS OF BOLTS.SC3.1 Need for fatigue analysis.Unless the vessel on which they are installed satisfies allthe conditions of Paragraph SC1.2 and thus requires no fatigue analysis, the suitability ofbolts for cyclic operation shall be determined in accordance with this Paragraph (SC3).SC3.2 Methods of fatigue analysis.Bolts made of materials which have specified minimumtensile strengths of less than 686 MPa shall be evaluated for cyclic operation in accordancewith Paragraph SC2 using the applicable design fatigue curves of Figure SC1.2.1 orFigure SC1.2.2 and an appropriate stress concentration factor.High strength alloy steel bolts and studs may be evaluated for cyclic operation in accordancewith Paragraph SC2 using the design fatigue curve of Figure SC3.2 provided that thefollowing requirements are complied with:(a) The material is within the following limits:
Chromium 0.8 percent to 1.15 percentNickel 1.65 percent to 2.00 percentMolybdenum 0.20 percent to 0.65 percentSpecified yield strength 539 MPa to 981 MPaSpecified tensile strength 686 MPa to 1128 MPa
FIGURE SC3.2 DESIGN FATIGUE CURVES FOR HIGH STRENGTH STEELBOLTING FOR TEMPERATURES ≤375°C
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(b) The maximum value of the service stress at the periphery of the bolt cross-section(resulting from direct tension plus bending and neglecting stress concentrations) shallnot exceed 2.7f if the higher of the two fatigue design curves shown in Figure SC3.2is used or shall not exceed 3f if the lower of the two curves is used. In both cases theactual direct tension stress (averaged across the bolt cross-section) produced by thecombination of preload, pressure, and differential thermal expansion, but neglectingstress concentrations, shall not exceed 2f.
(c) Threads shall be of ‘V’ type, having a minimum thread root radius not less than0.075 mm.
(d) Fillet radii at the end of the shank shall be such that the ratio of fillet radius to shankdiameter is not less than 0.060.
Unless it can be shown by analysis or test that a lower value is appropriate, the fatiguestrength reduction factor used in the fatigue evaluation of threaded members shall be notless than 4.0.
S3.3 Cumulative damage.The bolts shall be acceptable for the specified cyclic applicationof loads and thermal stresses provided that the cumulative usage factorU as determined inaccordance with Paragraph SC2.2.5 does not exceed 1.0.
SC4 FATIGUE TEST FOR CYCLIC OPERATION.
SC4.1 Basic assumption.The general procedure in fatigue evaluation is based on the useof strain controlled fatigue data. The resulting fatigue design curve is a composite curve. Inthe low cycle range the stress amplitude is primarily a function of the true fracture strainmultiplied by the elastic modulus. In the high cycle range the stress amplitude is, as a matterof convenience, made equal to the endurance limit.
This method should result in families of curves rather than the curves in Figures SC1.2.1and SC1.2.2 which are based on a large number of tests carried out on steels having diversematerial properties. However, owing to the very wide scatter of test points it was found thatonly a lower limit curve could be justified.
The method, therefore, discriminates against a number of steels, particularly against thosein the high strength range. To permit a better evaluation of the fatigue strength of suchmaterials, or where it is desired to use higher peak stresses than can be justified by themethods of the previous rules, the adequacy of a part to withstand cyclic loading may bedemonstrated by means of a fatigue test. However, the fatigue test shall not be used asjustification for exceeding the allowable values of primary or primary-plus-secondarystresses.
SC4.2 Testing of component.The test component or that portion to be tested shall beconstructed of material having the same composition as the vessel component and shall besubjected to the same mechanical working and heat treatment so as to produce mechanicalproperties equivalent to those of the material in the prototype component. Geometricalsimilarity must be maintained, at least in those portions whose ability to withstand cyclicloading is being investigated and in those adjacent areas which affect the stresses in theportion under test.
The test component or portion thereof shall withstand the number of cycles as specifiedbelow without failure. Failure is defined herein as a propagation of a crack through theentire thickness, such as would produce a measurable leak in a pressure-retaining member.
The minimum number of cycles (hereinafter referred to as ‘test cycles’) which thecomponent must withstand, and the magnitude of the loading (hereinafter referred to as ‘thetest loading’) to be applied to the component during the test, shall be determined bymultiplying the design service cycles by a specified factorKn′, and the design service loadsby Ks′. Values of these factors shall be determined from a composite fatigue curveconstructed in accordance with Paragraph SC4.3.
SC4.3 Construction of test fatigue curve.The fatigue test curve is drawn from theapplicable original fatigue curve. It is less conservative than the original curve in order tocompensate for the higher allowable stresses.
(a) Construct the test fatigue curve by multiplying the values ofSa of the original curveby the factorKs and draw a new fatigue curveSas through these points, as shown inFigure SC4.3. Next, construct a second fatigue curve by multiplying the values ofNin the original curve byKn and draw a second fatigue curveSan through these points,as shown in Figure SC4.3. The test fatigue curveSa′ is constructed using the highersegments ofSas and San, as shown in Figure SC4.3. (See Paragraph SC4.3 (c) fornotation.)
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(b) Assume the service condition for the prototype vessel to beSa andN, defined by pointA on the original curve. Project point A vertically and horizontally to points D and Con the test curvesSa′. The segment ofSa′ between the two points C and D embracesall allowable combinations ofKs′ and Kn′. The values for a point B determines thefollowing corresponding values ofKs′ andKn′:
Ks′ = Kn′ =
Test loadingPt = Ks′ × design service loading
Test cyclesNn = Kn′ × design service cycles
The designer therefore has available a choice of test cycling conditions ranging from —
Point D,
whereKs′ = ordinate A;Kn′ = 1, signifying a maximum increase of load amplitudeand no change in number of cycles,
to —
Point C,
whereKs′ = 1; Kn′ = abscissa D/abscissa A, signifying an increase of number ofcycles and no change of load amplitude, when compared with thefatigue design requirements of the prototype vessel.
(c) The values ofKs andKn are the multiples of factors which account for the effects ofsize, surface finish, cyclic rate, temperature, and the number of replicate testsperformed. They shall be determined as follows:
Ks = Ksl × K sf × K ss but shall never be allowed to be less than 1.25
K = Ks4.3 but shall never be allowed to be less than 2.6
Ksl = factor for the effect of size on fatigue life = 1.5 – 0.5 (LM/LP), whereLM/LP is the ratio of linear model size to prototype size
FIGURE SC4.3 CONSTRUCTION OF TEST FATIGUE CURVE
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Ksf = factor for the effect of surface finish = 1.75 - 0.175 (SFM/SFP)where (SFM/SFP) is the ratio of the model surface finish to the prototypesurface finish expressed in arithmetic average
Kss = factor for the statistical variation in test results= 1.220 - 0.44× number of replicate tests
No value ofKsl, Ksf or Kss less than 1.0 may be used in the calculation ofKs.
(d) AdditionalK-factors can be found in technical literature, covering other conditions. Thedesigner will also be faced with conditions for which data are not available, in whichcase theK-factors must be developed from tests in accordance with Paragraph SC5.
SC5 DETERMINATION OF FATIGUE STRENGTH REDUCTION FACTORS. Thefollowing criteria are applicable in the determination of fatigue strength reduction factors:
(a) A reduction in fatigue strength of a component may be due to the presence of a notch,a ‘notch’ for the purpose of this Supplement being an actual notch or an abrupt changein cross-section, or a transition section of differing curvatures, or attachments forsupports, or penetrations into shells, e.g. drill holes and welded nozzles with varyingdiameters and corner radii.
(b) The fatigue strength reduction factor shall be determined by tests on ‘notched’ and‘unnotched’ specimens and calculated as the ratio of the ‘unnotched’ stress to the‘notched’ stress for failure or other equivalent methods.
(c) The test part shall be fabricated from the same material and shall be subjected to thesame heat treatment as the component.
(d) The stress level in the specimen shall not exceed the limit given inParagraph SH2.4.3(d), Appendix SH, and shall be such that failure does not occur inless than 1000 cycles.
(e) The configuration, surface finish, and stress state of the specimen shall closely simulatethose expected in the components. In particular, the stress gradient shall not be moreabrupt than expected in the component.
(f) The cyclic rate shall be such that appreciable heating of the specimen does not occur,nor shall it exceed 100 Hz.
SC6 CYCLIC THERMAL STRESSES. The following requirements are applicable tocyclic thermal stress conditions:
(a) Pressure vessels which operate at elevated or subzero temperature should be heated orcooled slowly, and should be efficiently lagged to minimize temperature gradients inthe shells. Rapid changes of shell temperature should be avoided during service.
(b) The vessels should be able to expand and contract without undue restraint.
(c) Provided that the conditions in (a) and (b) above and those of Paragraph SC3 areobserved, estimates of thermal stresses due to temperature changes need not bespecially considered.
(d) The use of pad-type reinforcement or partial penetration joints is not suitable for caseswhere there are significant temperature gradients, especially where these are of afluctuating nature.
SC7 FORCED VIBRATIONS. Pulsations ofpressure, wind-excitedvibrations or vibrationstransmitted from plant, e.g. rotating or reciprocating machinery, may cause vibrations ofpiping or local resonance of the shell of a pressure vessel. In most cases these cannot beanticipated at the design stage. It is therefore advisable to make an examination of plantfollowing initial start-up. If such vibration occurs and is considered to be excessive, thesource of the vibration should be isolated, by stiffening, additional support or dampingwhich should be introduced at a location local to the vibration.
SC8 CORROSION FATIGUE. Corrosion conditions are detrimental to the endurance ofcarbon steels, carbon-manganese steels, and ferritic alloy steels. Fatigue cracks may occurunder such conditions at low levels of fluctuation of applied stress. Since the tensile strengthof a steel has little or no effect upon the fatigue strength under corrosive conditions, the useof high strength steels in severe corrosion fatigue service will offer no advantage unless thesurface is effectively protected from the corrosive medium. Where corrosion fatigue isexpected, it is desirable to minimize the range of cyclic stresses and carry out inspection atsufficiently frequent intervals to establish the pattern of behaviour.
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APPENDIX SD
RECOMMENDED CORROSION PREVENTION PRACTICE
Appendix D of AS 1210 applies.
APPENDIX SE
INFORMATION TO BE SUPPLIED BY THE PURCHASERTO THE MANUFACTURER
Appendix E of AS 1210 applies, with the following addition:
It is the purchaser’s responsibility to specify or cause to be specified (see Clause S3.1.2) thefollowing:
(a) Information in sufficient detail that the need for a fatigue analysis can be determinedand that any required analysis can be carried out.
(b) Whether or not a corrosion (and erosion) allowance is required, and if so the amount.
(c) Whether or not the vessel will contain lethal material (see Clause 1.7.1).
APPENDIX SF
INFORMATION TO BE SUPPLIED BY THE MANUFACTURER
Appendix F of AS 1210 applies.
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APPENDIX SH
DESIGN REQUIREMENTS FOR LOADINGS AND COMPONENTSNOT COVERED BY SECTION 3
(This Appendix forms an integral part of this Supplement.)
Appendix H of AS 1210 does not apply to this Supplement and the following shall besubstituted:
SH1 GENERAL. This Appendix specifies design criteria for stress systems resulting fromthe application of loads or the use of components of types not covered explicitly bySection S3.
The intention is to ensure that the design basis for these components and loadings shall beconsistent with that underlying the specific requirements given in Section S3.
Formal analysis in accordance with this Appendix is required only in the case of significantadditional loadings, or for components significantly different from those dealt with inSection S3. Relevant experience of similar designs may be considered in deciding whetheran analysis is required.
SH2 NON-CREEP CONDITIONS.
SH2.1 Design criteria.For design temperatures at which the nominal design strength isgoverned by one of the two short-term mechanical propertiesRe(T) andRm, the followingdesign criteria shall be applied:
(a) Gross plastic deformation.There should be the same theoretical margin against grossplastic deformation for all design details as that provided against gross plasticdeformation in major membrane areas. For this purpose, the required margin againstgross plastic deformation may be assumed to beRe(T)/f for materials covered inTable S3.3.1. For other materials the value of the nearest equivalent material inTable S3.3.1 should be assumed.
(b) Incremental collapse.The stress systems imposed shall shakedown to elastic actionwithin the first few operating cycles. The operating loads to be considered includepressure and simultaneous loadings of types listed in Clause S3.2.3 including thermalstresses.
(c) Buckling.For components or loadings associated with substantial compressive stresses,buckling shall not occur under a combined load less than twice the design combinedload, at design temperature*. The design is to include pressure and simultaneousloadings of types given in Clause S3.2.3.
The design shall also take into consideration all permissible fabrication imperfections.
(d) Fatigue. The need, or otherwise, for a fatigue analysis shall be determined inaccordance with Clauses S3.1.5.4 to S3.1.5.7.
SH2.2 Design acceptability.The results of experimental or theoretical investigations shallbe employed to demonstrate the conformity of a design with the criteria of Paragraph SH2.1.Local stresses in the vicinity of attachments, supports, etc, may be deemed acceptable ifthey comply with the requirements of Paragraph SH2.3.
In the establishing of compliance with Paragraph SH2.1(a), investigations should takeaccount of plastic behaviour. If the theory of plastic limit analysis is employed, the limitload may be taken as the load that produces gross plastic deformation, although this maybe a conservative estimate. Where it is impracticable to perform a plastic analysis, an elasticanalysis may be employed as detailed in Paragraph SH3.4; alternatively, strainmeasurements may be made on the actual vessel during pressure and load tests.
In the establishing of compliance with Paragraph SH2.1(b), a shake-down analysis shouldpreferably be performed; alternatively, an elastic analysis may be employed as detailed inParagraph SH2.3.
SH2.3 Specific criteria for local stresses in vicinity of attachments, supports, etc.Elastically calculated stresses due to local loads at attachments, supports, etc, may bedeemed acceptable provided that —
(a) they occur in areas at a distance not less than 2.5 (Rt) from shell discontinuities andhave a dimension in the circumferential direction not greater than one-third of the shellcircumference;
* Care is to be taken under test conditions to avoid buckling.
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(b) the direct stress intensity under relevant conditions of local loading does not exceedfor 1.2f as permitted in Table S3.1.5; and
(c) the stress intensity due to the sum of direct and bending stresses does not exceed 2f.
For nozzles and openings such stresses may be deemed acceptable provided that —
(i) a nozzle or opening is not less than 2.5 (Rt) from other shell discontinuities;(ii) the nozzle or opening is reinforced in accordance with Clause 3.19; and
(iii) the maximum surface stress calculated for the gross structural discontinuity does notexceed 2.25f.
Where significant compressive stresses are present, the possibility of buckling should beinvestigated and the design modified if necessary (see Paragraph SH2.1(c)).
In cases where external load is highly localized, an acceptable procedure should be to limitthe algebraic sum of all stresses acting at the point to 0.9 of the specified minimum yieldstress of the material.
Where only shear stress is present, it should not exceed 0.5f.
The maximum permissible bearing stresses should not exceed 1.5f.
SH2.4 Specific criteria for general application.SH2.4.1General.Paragraphs SH2.4.2 to SH2.4.5 provide the criteria for acceptability ofdesign on the basis of elastic stress analysis. The analysis should take account of grossstructural discontinuities, e.g. nozzles, changes in shell curvature, but not of local stressconcentrations due to changes in profile such as fillet welds.The rules require the calculated stresses to be grouped in five stress categories (seeParagraph SH2.4.3) and appropriate stress intensitiesfm, fL, fb, fg, andfp to be determinedfrom the principal stressesf1, f2, andf3 in each category, in accordance with the maximumshear theory of failure. Appropriate stress limits are given for the stress intensity socalculated.
SH2.4.2Terms relating to stress analysis.Terms used in this Appendix relating to stressanalysis are defined as follows:
(a) Stress intensity— twice the maximum shear stress. In other words, the stress intensityis the difference between the algebraically largest principal stress and the algebraicallysmallest principal stress at a given point. Tension stresses are considered positive andcompression stresses are considered negative.
(b) Gross structural discontinuity— a source of stress or strain intensification whichaffects a relatively large portion of a vessel and which has a significant effect on theoverall stress or strain pattern or has a significant effect on the vessel as a whole.
Examples of gross structural discontinuities are head-to-shell and flange-to-shelljunctions, nozzles and junctions between shells of different diameters or thicknesses.
(c) Local structural discontinuity— source of stress or strain intensification which affectsa relatively small volume of material but which does not have a significant effect onthe overall stress or strain pattern or on the structure as a whole.Examples of local structural discontinuities are small fillet radii, small attachments andpartial penetration welds.
(d) Normal stress— the component of stress normal to the plane of reference. (This isalso referred to as ‘direct stress’.)
Usually the distribution of normal stress is not uniform through the thickness of a part,so this stress is considered to be made up in turn of two components, one of which isuniformly distributed and equal to the average value of stress across the thickness ofthe section under consideration and the other of which varies with the location acrossthe thickness.
(e) Shear stress— the components of stress tangent to the plane of reference.
(f) Membrane stress— the component of normal stress which is uniformly distributed andequal to the average value of stress across the thickness of the section underconsideration.
(g) Primary stress— a stress produced by mechanical loadings only and which is sodistributed in the structure that no redistribution of load occurs as a result of yielding.It is a normal stress or a shear stress developed by the imposed loading which isnecessary to satisfy the simple laws of equilibrium of external and internal forces andmoments. Primary stresses that considerably exceed the yield stress will result infailure, or at least in gross distortion. A thermal stress is not classified as a primarystress. Primary stress is divided into ‘general’ and ‘local’ categories. The local primarystress is defined in (h) below.
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Examples of general primary stresses are —
(i) the stress in a circular, cylindrical or spherical shell due to internal pressure orto distributed live loads; and
(ii) bending stress in the central portion of a flat head due to pressure.
(h) Local primary stress— cases arise in which a membrane stress produced by pressureor other mechanical loading and associated with a primary or a discontinuity effect orboth, produces excessive distortion in the transfer of load to other portions of thestructure. Conservatism requires that such a stress be classified as a local primarymembrane stress even though it has some characteristics of a secondary stress. Astressed region may be considered as local if the distance over which the stressintensity exceeds 1.1f does not extend in the meridional direction more than 0.5 (Rt)and if it is not closer in the meridional direction than 2.5 (Rt) to another region wherethe limits of general primary membrane stress are exceeded. (R is the distancemeasured along the perpendicular to the surface from the axis of revolution of thevessel to the midsurface of the vessel;t is the wall thickness at the location where thegeneral primary membrane stress limit is exceeded.)
An example of a primary local stress is the membrane stress in a shell produced byexternal load and moment at permanent support or at a nozzle connection.
(i) Secondary stress— a normal stress or a shear stress developed by the constraint ofadjacent parts or by self-constraint of a structure. The basic characteristic of asecondary stress is that it is self-limiting. Local yielding and minor distortions cansatisfy the conditions which cause the stress to occur, and failure from one applicationof the stress is not to be expected.An example of secondary stress is bending stress at a gross structural discontinuity.
(j) Peak stress— the basic characteristic of a peak stress is that it does not cause anynoticeable distortion and is objectionable only as a possible source of a fatigue crackor a brittle fracture. A stress which is not highly localized falls into this category if itis of a type which cannot cause noticeable distortion.
Examples of peak stress are —
(i) the thermal stress in the austenitic steel cladding of a carbon steel vessel;
(ii) the surface stresses in the wall of a vessel or pipe produced by thermal shock;and
(iii) the stress at a local structural discontinuity.
SH2.4.3Stress categories and stress limits.A calculated stress depending upon the type ofloading or the distribution of such stress will fall within one of the five basic stresscategories defined below. For each category, a stress intensity value is derived for a specificcondition of design. This stress intensity, to satisfy the analysis, should fall within the limitspecified in each category. The limits are summarized in Figure SH2.4.3.
(a) General primary membrane stress category— the stresses falling within this categoryare those defined as general primary stresses in Paragraph SH2.4.2(g) and are producedby pressure and mechanical loads, but exclude all secondary and peak stresses. Thevalue of the membrane stress intensity is obtained by averaging these stresses acrossthe thickness of the section under consideration. The limiting value of this stressintensity (fm) is kf, using values ofk as permitted in Table S3.1.5.
(b) Local primary membrane stress category— the stresses falling within this category arethose defined in Paragraph SH2.4.2(h) and are produced by pressure and mechanicalloads, but exclude all thermal and peak stresses. The stress intensity (f L) is the averagevalue of these stresses across the thickness of the section under consideration and islimited to 1.5kf.
(c) General or local primary membrane plus primary bending stress category— thestresses falling within this category are those defined in Paragraph SH2.4.2(g), but thestress intensity value [(fb), (fm + fb), or (fL + fb)] is the highest value of those stressesacting across the section under consideration excluding secondary and peak stresses.fb is the primary bending stress intensity, which means the component of primary stressproportional to the distance from the centroid of the solid section. The stress intensity[(fb), (fm + fb), or (fL + fb)] is limited to 1.5kf.
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(d) Primary plus secondary stress category— the stresses falling within this category arethose defined in Paragraph SH2.4.2(g) plus those of Paragraph SH2.4.2(j) produced bypressure, mechanical loads and general thermal effects. The effects of gross structuraldiscontinuities but not of local structural discontinuities (stress concentrations) shouldbe included. The stress intensity value [(fm + fb + fg) or (fL + fb + fg)] is the highestvalue of these stresses acting across the section under consideration and is to be limitedto 3.0kf (see also Note 1 of Figure SH2.4.3).
(e) Peak stress category— the stresses falling within this category are a combination ofall primary, secondary and peak stresses produced by specified operating pressures andmechanical loads and by general and local thermal effects, including the effects ofgross and local structural discontinuities. The stress intensity is the highest value ofthese stresses acting at any point across the thickness of the section underconsideration. The allowable value of this stress intensity is dependent on the range ofthe stress difference from which it is derived and on the number of times it is to beapplied. The stress intensity is to be compared with the allowable value obtained bythe methods of analysis for cyclic operation when fatigue analysis is required accordingto Appendix SC.
Figure SH2.4.3 and Table SH2.4.3 have been included to guide the designer inestablishing stress categories for some typical cases and stress intensity limits forcombinations of stress categories. There will be instances when reference to definitionsof stresses will be necessary to classify a specific stress condition to a stress category.Item (f) below explains the reason for separating them into two categories ‘general’ and‘secondary’.
(f) Thermal stress— a self-balancing stress produced by a non-uniform distribution oftemperature or by differing thermal coefficients of expansion. Thermal stress isdeveloped in a solid body whenever a volume of material is prevented from assumingthe size and shape that it normally should under a change in temperature.
For the purpose of establishing allowable stresses, two types of thermal stress arerecognized, depending on the volume or area in which distortion takes place, asfollows:(i) General thermal stress is associated with distortion of the structure in which it
occurs. If a stress of this type, neglecting stress concentrations, exceeds twice theyield strength of the material, the elastic analysis may be invalid and successivethermal cycles may produce incremental distortion. Therefore, this type isclassified as secondary stress in Table SH2.4.3 and Figure SH2.4.3.
Examples of general thermal stress are —
(A) stress produced by an axial thermal gradient in a cylindrical shell; and
(B) stress produced by the temperature difference between a nozzle and theshell to which it is attached.
(ii) Local thermal stress which is associated with almost complete suppression of thedifferential expansion and thus produces no significant distortion. Such stressesshall be considered only from the fatigue standpoint and are therefore classifiedas peak stresses in Table SH2.4.3 and Figure SH2.4.3.
Examples of local thermal stress are —
(A) the stress in a small hot spot in a vessel wall;
(B) stress from a radial temperature gradient in a cylindrical shell; and(C) the thermal stress in a cladding material which has a coefficient of
expansion different from that of the base metal.
SH2.4.4Value of Poisson ratio.The value of Poisson ratio shall be determined as follows:
(a) In the evaluation of stresses for comparison with any stress limits other than thoseallowable under fatigue conditions, stresses shall be calculated on an elastic basis usingthe elastic value of Poisson ratio.
(b) In the evaluation of stresses for comparison with the allowable stress limits associatedwith fatigue conditions, the elastic equations shall be used, except that the numericalvalue substituted for Poisson ratio should be determined from the following equation:
ν = 0.5 - 0.2 ≥ 0.3
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where
fy = yield strength of the material at the mean value of the temperature ofthe cycle
Sa = value obtained from the applicable design fatigue curve (AppendixSC, Figures SC1.2.1 and SC1.2.2) for the specific number of cyclesof the condition being considered
SH2.4.5Triaxial stresses.The algebraic sum of the three principal stresses (σ1 + σ2 + σ3)in any category shall not exceed 3.75f.
SH3 CREEP CONDITIONS. Comprehensive design criteria for components in the creeprange are not yet available. In the meantime, the requirements of Section 3 may be used.
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TABLE SH2.4.3CLASSIFICATION OF STRESSES FOR SOME TYPICAL CASES
Vessel component Location Origin of stress Type of stress Classification
Cylindrical or sphericalshell
Shell plate remote fromdiscontinuities
Internal pressure General membrane gradientthrough plate thickness
fm
Axial thermal gradient MembraneBending
fg
fg
Junction with head orflange
Internal pressure MembraneBending
fLfg
Any shell or end Any section across entirevessel
External load or moment,or internal pressure
General membrane averagedacross full section. Stresscomponent perpendicular tocross-section
fm
External load or moment Bending across full section.Stress component perpendicularto cross-section
fm
Near nozzle or otheropening
External load or moment,or internal pressure
Local membraneBendingPeak (fillet or corner)
fLfg
fp
Any location Temperature differencebetween shell and head
MembraneBending
fg
fg
Dished end or conical end Crown Internal pressure MembraneBending
fmfb
Knuckle or junction to shell Internal pressure MembraneBending
fL*fg
Flat end Centre region Internal pressure MembraneBending
fmfb
Junction to shell Internal pressure MembraneBending
fLfg
Perforated end or shell Typical ligament in auniform pattern
Pressure Membrane averaged throughcross-sectionBending (averaged through widthof ligament, but gradient throughplate)Peak
fm
fb
fp
Isolated or typical ligament Pressure MembraneBendingPeak
fg
fp
fp
Nozzle Cross-section perpendicularto nozzle axis
Internal pressure or externalload or moment
General membrane (averagedacross full section). Stresscomponent perpendicular tosection
fm
External load or moment Bending across nozzle section fm
Nozzle wall Internal pressure General membraneLocal membraneBendingPeak
fmfLfg
fp
Differential expansion MembraneBendingPeak
fg
fg
fp
Cladding Any Differential expansion MembraneBending
fp
fp
Any Any Thermal gradient throughplate thickness
Bending fp†
Any Any Stress concentration (notcheffect)
fp
* Consideration should also be given to the possibility of buckling and excessive deformation in vessels with large diameter/thickness ratio.† Consider possibility of thermal stress ratchet.
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NOTES:1. This limitation applies to the range of stress intensity. Where the secondary stress is due to a temperature excursion at the point at which the
stresses are being analysed, the value off is to be taken as the average of thef-values for the highest and the lowest temperature of the metalduring the transient. Where part or all of the secondary stress is due to mechanical load, the value off is to be taken as thef-value for thehighest temperature of the metal during the transient.
2. The stresses in categoryfg are those parts of the total stress which are produced by thermal gradients, structural discontinuities, etc, and do notinclude primary stresses which may also exist at the same point. It should be noted however, that a detailed stress analysis frequently gives thecombination of primary and secondary stresses directly and, when appropriated, this calculated value represents the total offm (or fL) + fb + fg
and notfg alone. Similarly, if the stress in categoryfp is produced by a stress concentration, the quantityp is the additional stress produced bythe notch, over and above nominal stress. For example, if a plate has a nominal stress intensityf1 and has a notch with a stress concentrationfactor K, thenfm = f1, fb = 0, fp = fm(K – 1) and the peak stress intensity equalsfm + fm (K – 1) = Kfm.
3. Sa is obtained from the fatigue curves (Appendix SC, Figures SC1.2.1 and SC1.2.2). The allowable stress intensity for the dull range offluctuation is 2Sa.
4. The symbolsfm, fL, fb, fg andfp do not represent single quantities, but rather six quantities representing the six stress components,σt, σ l, σr, τt,τlr andτrt.
5. The factork is obtained from Table S3.1.5.
FIGURE SH2.4.3 STRESS CATEGORIES AND LIMITS OF STRESS INTENSITY
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APPENDIX SK
LOW TEMPERATURE VESSELS
Appendix K of AS 1210 applies.
APPENDIX SR
LIST OF REFERENCED DOCUMENTS
Appendix R of AS 1210 applies.
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