As 1210 Supplement 1 - Unfired Pressure Vessels - Advanced D

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Australian Standard



Unfired pressure vessels —

Advanced design and

construction

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Pressure Vessels. It was approved on behalf of the Council of Standards Australia on 20 October 1989 and published on 2 April 1990.

The following interests are represented on Committee ME/1: Aluminium Development Council

Australian Compressed Air Institute

Australian Institute for Non-destructive Testing Australian Institute of Energy

Australian Institute of Petroleum

Australian Liquefied Petroleum Gas Association Australian Valve Manufacturers Association

Boiler and Pressure Vessel Manufacturers Association of Australia Bureau of Steel Manufacturers of Australia

Confederation of Australian Industry Department of Defence

Department of Industrial Affairs, Qld Department 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 Territories Electricity Supply Association of Australia

Institute of Metals and Materials Australasia Institution of Engineers Australia

Insurance Council of Australia

Metal Trades Industry Association of Australia National Association of Testing Authorities Australia Railways of Australia Committee

Society of Mechanical Engineers of Australasia Sugar Research Institute

Welding Technology Institute of Australia Work Health Authority, N.T.

Workcover, N.S.W.

Review of Australian Standards. To keep abreast of progress in industry, Australian Standards are subject

to periodic review and are kept up to date by the issue of amendments or new edit ions as necessary. It is important therefore that Standards users ensure that they are in possession of the latest editi on, and any amendments thereto.

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Suggesti ons for improvements to Australi an Standards, addressed to the head offi ce of Standards Australi a, are welcomed. Noti fi cati on of any inaccuracy or ambiguity found in an Australian Standard should be made without delay in order that the matter may be investigated and appropriate action taken.

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Australian Standard



Unfired pressure vessels —

Advanced design and

construction

(Supplement to AS 1210—1989)

First publi shed as AS CB1 Int.6—1969.

Revised and redesignated AS 1210 Supplement 1—1979. Second editi on 1984.

Thir d editi on 1990. Incorporating: Amdt 1—1995 Amdt 2—1997

PUBLISHED BY STANDARDS AUSTRALIA (STANDARDS ASSOCIATION OF AUSTRALIA) 1 THE CRESCENT, HOMEBUSH, NSW 2140

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PREFACE

This edition of this Supplement was prepared by the Standards Australia Committee on Boilers and Unfired Pressure Vessels to supersede Supplement No 1 (June 1984) to AS 1210, SAA Unfired Pressure Vessel Code, Class 1H Pressure Vessels of Advanced Design and Construction. It forms part of the SAA Boiler Code (AS 1200) which is referred to in Statutory Regulations in Australia, and which covers requirements for land installations of shell boilers, water-tube boilers, unfired pressure vessels, pressure piping, welder certification, and related matters.

The Supplement provides for additional classes of vessels which require more precise design procedures to ensure that the higher design stresses can be tolerated for the particular 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 welded vessel (Class 2H) which permits the use of the higher design strengths applicable to Class 1H vessels with reduced levels of non-destructive examination but with the restrictions on the range and the thickness of materials used and the fatigue criteria under which the Class 2H vessels may be used. The introduction of requirements for Class 2H vessels was delayed until a full review of the material requirements in AS 1210, SAA Unfired Pressure Vessels Code, for low temperature service had been carried out.

An alternative method for assessing the need for a detailed fatigue analysis of the vessel and its components has been introduced.

Other revisions in this edition include a change of the membrane stress intensity limits for the test condition, clarification of the design strengths to be used in the design of flanges, changes in the requirements for clad plate and for low temperature service and clarification of coverage of cast and forged vessels.

The Supplement deals only with stationary vessels for a specific service where operation and maintenance control is fully exercised during the useful life of the vessel by the users in accordance with specified operating requirements for the vessel. This Supplement lists only those requirements which differ from or are additional to those for Class 1 vessels in AS 1210. Together with AS 1210 it will directly satisfy the needs of most vessels. For complicated vessels or for vessels that are subject to unusual loads or fatigue, a comprehensive stress/load analysis is required.

This Supplement requires that all vessels be reviewed to ensure that unusual and excessive loads and fatigue cycling are maintained within safe limits. It prescribes detailed fatigue analysis where and when necessary. For vessels that are cleared from such 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 is required, 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. Some authoritative national standards such as ANSI/ASME BPV-VIII-2, Boiler and Pressure Vessel Code: Section VIII — Rules for construction of pressure vessels: Division 2 — Alternative rules, and BS 5500, Specification for unfired fusion welded pressure vessels, provide tested shortcuts to many solutions encountered in advanced vessel design. These may be used, where appropriate by the designer as substitutes for fundamental stress analysis.

Acknowledgement is gratefully made to the American Society of Mechanical Engineers for permission to reproduce certain extracts from the ASME Boiler and Pressure Vessel Code. In addition, acknowledgement is made of the considerable assistance provided by British and other national Standards.

The International Organization for Standardization (ISO) Technical Committee ISO/TC 11 — Boilers and Pressure Vessels, has prepared a draft International Standard, ISO/DIS 2694, ISO draft recommendation for pressure Vessels, with the object of achieving agreement regarding uniformity of approach in national standards covering this subject. At this time, significant differences between the various national standards 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 1210 Supplement 1 is suitable for use with the 1997 edition of AS 1210, Pressure vessels.

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FOREWORD

The application of the several Standards that form the SAA Boiler Code may give rise to a need for consideration of unusual and other designs which do not comply in all respects with the requirements of the relevant Standard or which are not adequately covered in any Standard.

Where it is desired to use materials or methods which do not comply with the requirements of, or are not adequately covered by the relevant Standard, designs incorporating such departures should be submitted to the relevant Inspecting Authority for approval. Where necessary, Standards Australia Committee ME/1, Boilers and Unfired Pressure Vessels, may be asked to serve in an advisory capacity in the determination 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 of the Code and that the committee has no power or jurisdiction to adjudicate upon contractual matters or regulatory matters or the duties of any persons concerned with the subject of the submission.

It is further emphasized that the committee will undertake consideration of only those matters which relate to interpretation of, or proposed changes to, the Standards for which it is responsible. In particular it will not consider or make recommendations indicating approval of proprietary equipment, materials, components, or methods. A method developed by the committee for communicating its findings is the use of Rulings. A Ruling is issued in reply to a specific enquiry from a specific organization and applies only to the set of circumstances referenced in the Ruling. Rulings may be used by the authorities as the basis for approval of the particular application or for approval of similar submissions from other organizations. Current Rulings are available under the reference AS 1200 Supplement 1.

Where the committee judges the subject to be suitable, a Ruling may be incorporated in an amendment to the relevant Standard, whereupon the Ruling is withdrawn. If the timing is appropriate, the finding of the committee may be issued directly as an amendment.

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 ‘I nterpretations’ which were considered to be equivalent to an amendment. The practice has been disconti nued, and all Interpretations have now been withdrawn.

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STANDARDS AUSTRALIA

Australian Standard

Unfired 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 following additions:

Supplement 1 (hereafter referred to as ‘the Supplement’ or ‘this Supplement’) specifies requirements for two additional classes of vessel identified as Class 1H and Class 2H with the latter further subdivided into classifications 2HA and 2HB, and for cast and forged vessels, which —

(a) utilize advanced design and construction methods; (b) generally permit design strengths higher than those

specified in AS 1210; and

(c) comply with the requirements specified in AS 1210 for cast, forged or Class 1 welded vessels as appropriate, except as modified by this Supplement. This Supplement does not apply to transportable vessels nor does it apply to vessels of riveted or brazed construction. Only those requirements which supplement or differ from those specified in AS 1210 for cast, forged or Class 1 welded construction are specified in this Supplement.

S1.3 APPLICATION OF SUPPLEMENT. Clause 1.3 applies except that the first paragraph shall be replaced by the following:

The requirements of this Supplement are specifically intended for application to unfired pressure vessels having —

(a) design pressures above the curves in Figures 1.3.1 and 1.3.2; and

(b) operating temperature limits of various materials and components as stated in the appropriate Section of this Supplement.

NOTE: The Supplement does not specify a limitation on pressures and is not all-inclusive for all types of construction. For very high pressures, some additions to or deviations from the requirements of this Supplement, to the satisfaction of the Inspecting Authority and purchaser, may be necessary.

S1.6 CLASSES OF VESSEL CONSTRUCTION. Clause 1.6 applies with the following addition:

This Supplement specifies the requirements for two additional classes of vessels, viz Class 1H and Class 2H, and the latter is subdivided into classifications 2HA and 2HB.

The range of materials permitted for Class 2H construction (see Clause S2.1.1) is limited but the extent of non-destructive examination may be reduced from that required 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 2HB respectively, are fulfilled (see Clause S3.1.5.4).

S1.7 APPLICATION OF VESSEL CLASSES AND TYPES. Clause 1.7 applies with the following modification:

S1.7.2.4 Mixed classes of construction. Clause 1.7.2.4 does not apply to this Supplement and the following shall be substituted:

See Clause S3.1.5.4 for the permissible mixing of components of Class 1H, Class 2HA, and Class 2HB construction.

S1.8 DEFINITIONS. Clause 1.8 applies, with the following additions and modifications to particular Clauses.

S1.8.10 Design strength. Clause 1.8.10 does not apply to this Supplement and the following shall be substituted: Design strength (f) — the maximum allowable stress value for use in the equations for the calculation of pressure parts, and the basis for determining stress intensity limits (see Clause S3.3).

S1.8.24 Parties concerned. Clause 1.8.24 does not apply to this Supplement and the following shall be substituted: Parties concerned — the purchaser, the manufacturer, Inspecting Authority, and the designer (see Clause S3.1.2).

S1.12 DESIGNATION. Clause 1.12 does not apply to this Supplement and the following shall be substituted: S1.12 DESIGNATION. Unfired pressure vessels constructed to this Supplement shall be designated by the number 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 — 1H For Class 2HA welded construction AS 1210 — 2HA For Class 2HB welded construction AS 1210 — 2HB For cast construction . . . AS 1210 — CH For forged construction . . . AS 1210 — FH For mixed construction — an appropriate combination of symbols, e.g. . . AS 1210 — 1H/2HA S1.13 REFERENCED DOCUMENTS. Clause 1.13 applies and this Supplement makes reference to the following documents:

AS

1065 Non-destructive testing — Ultrasonic testing of carbon and low alloy steel forgings 1200 SAA Boiler Code

1200 Supplement 1 — Rulings to the SAA Boiler Code

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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 low

alloy steel plate — Test methods and quality classification

ISO

R 783 Mechanical testing of steel at elevated temperatures — Determination of lower yield stress 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 construction

of pressure vessels: Division 2 — Alternative rules

ASTM

A 578 Specification for straight-beam ultrasonic examination of plain and clad steel plates for special applications

BS

3688 Methods for mechanical testing of metals at elevated temperatures

Part 1: Tensile testing

5500 Specification for unfired fusion welded pressure vessels

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SECTION S2. MATERIALS

Section 2 of AS 1210 shall apply, with the following additions and modifications to particular Clauses.

S2.1 MATERIAL SPECIFICATIONS. Clause 2.1 applies, with the following additions and modifications to particular Clauses:

S2.1.1 General. Clause 2.1.1 does not apply to this Supplement and the following shall be substituted: Any material used in the construction of Class 1H vessels shall comply with the specification listed in Tables 3.3.1(A), 3.3.1(B) and 3.3.1(D) to 3.3.1(H), and shall have the design strengths allocated in Table S3.3.1 (i) or (ii).

Any material used in construction of Class 2H vessels shall 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 strength allocated in Table S3.3.1(i) or (ii). For Class 2H vessels, the nominal shell plate thickness shall not exceed 38 mm.

NOTE: For steel groups, see Appendix P or Tables 3.3.1(A) and 3.3.1(B).

S 2.3 A L T ER N A T I V E M A TE R I A L A N D COMPONENT SPECIFICATIONS.Clause 2.3 applies with the following modification:

S2.3.3 Use of structural or similar quality steels. Clause 2.3.3 does not apply and the following shall be substituted:

Structural and similar quality steels shall be used only where requirements of Clause 2.3.4 are complied with.

S2.4 MATERIAL IDENTIFICATION. Clause 2.4 applies, with the following additions and modifications. S2.4.1 Unidentified material. The use of unidentified material is not permitted.

Not permitted.

S2.4.2 Material not fully identified. The use of material not fully identified is not permitted.

S2.6 MATERIAL REQUIREMENT FOR LOW TEMPERATURE SERVICE. Clause 2.6 applies with the following additions:

S2.6.2.6 Class 2H vessels. For Class 2H vessels, the required MDMT as determined from Table 2.6.3 shall be not less than 10°C below the MOT for vessel or vessel part.

S2.6.3.2(e) Modification for liquefied gas. For Class 2H vessels which contain liquefied gas, the required MDMT at full design strength shall be not more than 10°C higher than the atmospheric boiling point of the contents. S2.7 MATERIAL REQUIREMENTS FOR HIGH TEMPERATURE SERVICE. Clause 2.7 applies, with the following additions and modifications to particular Clauses:

S2.7.5 Steels. Clause 2.7.5 applies except that the first and second paragraphs shall be replaced by the following:

Steels for use at temperatures of 100°C or above shall be supplied with elevated temperature properties verified or hot-tested, except as provided below:

(a) Steels for which elevated temperature properties are specified in the relevant material specification but which have not been hot-tested or verified may be used. The design strength value shall be either as permitted by Table S3.3.1 or as determined by the factors in Table SA1.1 of Appendix SA.

(b) Steels for which elevated temperature properties are not specified in the relevant material specification may be used. (See Table S3.3.1(ii) for the design strength for such steels listed in ANSI/ASME BPV-VIII-2 or BS 5500.)

Where steel is to be used at a design temperature different from the standard test temperature in the particular material specification and is ordered hot-tested, the test shall be carried out at the nearest higher standard temperature given in the particular material specification. The material shall comply with the requirements of the material specification at the test temperature.

S2.8 NON- DEST RUCT IVE TEST ING OF MATERIALS. Clause 2.8 applies with the following addition:

All plates 100 mm and over in thickness shall be ultrasonically examined in accordance with AS 1710 or other approved method, and shall comply with the requirements for Class 2E quality level of AS 1710. For clad plate, where credit for the thickness of cladding on plate is permitted (see also Clause 3.3.1.2(c)), the bond between the cladding and the baseplate shall be ultrasonically examined.

All forgings 100 mm and over in thickness shall be ultrasonically examined in accordance with, and shall comply with the requirements of Clause S5.19.

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SECTION S3. DESIGN

Section 3 of AS 1210 shall apply, with the following additions and modifications to particular Clauses: S3.1 GENERAL DESIGN. Clause 3.1 applies with the following additions and modifications to particular Clauses:

S3.1.2 Design responsibility. Clause 3.1.2 does not apply to this Supplement and the following shall be substituted:

The design shall be carried out by a designer suitably qualified and experienced in the design of pressure vessels, who shall be responsible for the design of the vessel in accordance with this Section; and the design conditions shall either be specified by the purchaser (see Appendix SE) or be specified by the designer and approved by the purchaser.

A high level of qualification and experience would normally be required of a designer or design organization capable of adequately discharging the full requirements of this Supplement.

The designer may be associated with either the purchaser or the manufacturer, but, if not so associated, the designer shall be deemed to be one of the parties in the matters that require agreement of the parties concerned. S3.1.3 Alternative design methods. Clause 3.1.3 does not apply to this Supplement and the following shall be substituted:

Where an alternative design method is adopted, the general principles, design limits, fabrication, testing, and inspecting requirements of this Supplement shall be complied with.

In lieu of the requirements contained in this Supplement pertaining to the evaluation of design stress in a vessel or vessel component, it may be permitted to use a rigorous mathematical stress analysis, e.g. finite element method, or experimental stress analysis to evaluate the actual design stress. However, where complete requirements for the design of a vessel or vessel region are not provided in this Section (S3), a complete stress analysis (see Clause S5.12) shall be performed. Stress values obtained from such an analysis shall be used in conjunction with this Supplement to determine the minimum thickness of the vessel or vessel region. Other design methods may be used (see Foreword) except that the minimum thickness, where only the pressure loading is being considered, shall be not less than that required by Clauses S3.7 to S3.13.

S3.1.4 Design against failure. Clause 3.1.4 does not apply to this Supplement and the following shall be substituted:

The overall design of the vessel shall ensure against any mode of failure. The requirements of this Section (S3) are intended for use to determine the minimum thickness and other dimensions which provide safety against the risk 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 adequate ductility at the service temperature and at the design stresses considered, particularly in the regions of stress concentration.

Requirements to provide protection against brittle fracture and the requirements to ensure safe performance at low temperature are given in this Section (S3) and in AS 1210 (see Clause 2.6 and Appendix K).

The requirements of this Section (S3) also provide limited guidance on design against corrosion and apply only if the materials and welds are not subjected to stress corrosion in the presence of the product which the vessel is to contain.

S3.1.5 Design criteria.

S3.1.5.1 General. The minimum thickness of vessel parts subject only to fluid pressure shall be calculated from the equations given in Clauses S3.7 to S3.13. Where parts of the vessel are subject to loads in addition to that of fluid pressure, an equivalent stress intensity based on the maximum shear stress theory shall be calculated. For loads giving rise to primary membrane stresses, the equivalent stress intensity shall not exceed the design strength at the design temperature (see Clause S3.3) except as allowed for in Table S3.1.5. Where in addition to the primary membrane stress there are other stresses present, the equivalent stress intensity at any location shall not exceed the stress intensity limits given in Appendix SH (see Figure SH1). Clauses S3.7 and S3.13 may not ensure against fatigue failure. Thus reference shall be made to Clauses S3.1.5.4 to S3.1.5.7 to determine when the above Clauses are applicable or when recourse to further fatigue or other analysis is required.

Irrespective of whether credit is taken or is not taken for cladding in the computations for the dimensions of components for integrally clad vessels designed for operation at other than ambient temperature, calculation of the primary membrane stresses in both the base material and the cladding shall be performed and shall take into account any differential coefficients of expansion. The calculated stresses shall not exceed the relevant design strengths given in Table S3.3.1. S3.1.5.2 Maximum shear stress theory. The maximum shear stress at a point is defined as one-half of the algebraic difference between the largest and the smallest of the three principal stresses. Thus if the principal stresses are σ₁, 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 that yielding in a component occurs when the maximum shear stress reaches a value equal to the maximum shear stress at the yield stress in a tensile test. In such a tensile test —

σ1 = fy;σ2= 0; andσ3= 0 where

f_y = yield stress

and therefore the maximum shear stress is 0.5fy, and yielding occurs when —

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By analogy this equation can be written as — (σ₁–σ₃) = f ′

and the right-hand side is then called the equivalent intensity of combined stress or simply ‘stress intensity’. Thus the ‘stress intensity’ is defined as twice the maximum shear stress and is equal to the largest algebraic difference between any two of the three principal stresses and is directly comparable to yield stress values found from tensile tests.

S3.1.5.3 Application of maximum shear stress theory. Considering a thin cylindrical shell subject only to internal pressure loading, the following membrane stresses 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 thin of cylinder cylindrical shell P = internal pressure

f = design strength

t = wall thickness of cylinder

The mean radial stress for thin shells can therefore be taken as —

(σ_rad) mean =σ_mean = = -0.5P

From the above equations it then follows that the stress intensity is governed only byσ₁andσ₃and becomes —

f ′ = σ₁–σ₃ = – (−0.5P)

= + 0.5P which must not exceed the design strength f

Thus t = which is Equation 3.7.3(1) with joint efficiency equal to 1. If in addition to internal pressure the vessel part is subject to other loads, the absolute and the relative values of σ1,σ2, and σ3will vary and could lead to a wall thickness larger than that given by, say, Equation 3.7.3(1). Thus, if a slender cylinder is subject to bending, σ₂ could become larger than σ₁ and the calculated stress intensity would become equal to

σ2–σ3.

S3.1.5.4 Designing against fatigue failure — General. During the operation of pressure vessels, important parts may be subjected to cyclic or repeated stresses. Such stresses may be caused by —

(a) applications or fluctuations of pressure; (b) periodic temperature transients;

(c) restrictions of expansion or contraction during normal temperature variations;

(d) forced vibrations; or (e) variations in external loads.

Fatigue cracking will occur during the operational life if the fatigue strength of the material used in any part of the pressure vessel is exceeded for the particular number of repeated stress cycles. To prevent fatigue cracking, the level of cyclic stress or the expected number of cycles or both shall be reduced accordingly.

TABLE S3.1.5

MEMBRANE STRESS INTENSITY LIMITS FOR VARIOUS LOAD COMBINATIONS Condition Load combination Membrane stress

intensity limit (kf) Calculated stress limit basis

Design A The design pressure, the dead load of the vessel, the contents of the vessel, the imposed load of any mechanical equipment, and external attachment loads

1.0f (see Note 1) Based on the corroded thickness at design metal temperature

B Condition A above plus wind forces 1.2f Based on the corroded thickness at design metal temperature

C Condition A above plus earthquake forces NOTE: The condition of structural instability or buckling must be considered

1.2f Based on the corroded thickness at design metal temperature

Operation A The actual operating loading conditions. This is the basis of fatigue life evaluation

See Clauses S3.1.5.4 to S3.1.5.7

Based on corroded thickness at operating pressure and operating metal temperature Test A The required test pressure, the dead load of

the vessel, the contents of the vessel, the imposed load of any mechanical equipment, and external attachment loads

See Clause S5.10.2.1 for hydrostatic test, and Clause S5.11.4 for pneumatic test

Based on actual design values at test temperature

NOTES:

1. f is the design strength at the design temperature as determined by Clause S3.3.1.

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The alternative but technically equivalent methods for determining the need for a detailed fatigue analysis of Class 1H, Class 2HA, and Class 2HB vessels are given in Clauses S3.1.5.5 to S3.1.5.7 inclusive. In the first method, Clauses S3.1.5.5 and S3.1.5.6 specify requirements for integral parts of vessels and non-integral parts of vessels respectively, while the second method given in Clause S3.1.5.7 covers both integral and non-integral parts of the vessel.

In designing against fatigue, the designer shall pay particular attention to the possibledeleterious effects of the design features listed below. Unless their fatigue behaviour is satisfactorily assessed, their use shall be avoided. Design features 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 pipe outside 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 of fatigue, consideration should be given to the use of lower stress levels and to the extrapolation of the fatigue curves beyond 106cycles if necessary.

Procedures for determining compliance with the fatigue requirements of this Supplement for Class 1H, Class 2HA and Class 2HB vessels and vessel components shall be as specified in (A), (B) and (C) respectively of this Clause (S3.1.5.4).

(A) For Class 1H vessels or vessel components — provided that the requirements of Clauses S3.1.5.5 and S3.1.5.6, or of Clause S3.1.5.7 are fulfilled, it may be assumed that the requirements of this Supplement are complied with. If those requirements are not complied with by any component, peak stresses occurring in that component shall be calculated and a fatigue analysis of that component shall be carried out.

The method of fatigue analysis shall be in accordance with Appendix SC or other approved methods. In particular cases, other methods of analysis may be equally applicable, and the use of such methods together with safety factors equivalent to those used in Appendix SC shall be deemed to comply with the requirements of this Supplement.

NOTE: Apart from nickel-copper alloy, Appendix SC is not directly applicable to non-ferrous metals and alloys. For such materials a fundamental approach may be used (see Foreword). (B) For Class 2HA vessels and vessel components —

provided that the requirements for Class 1H vessels on 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, are fulfilled, the requirements of this Supplement are complied with for Class 2HA vessels. If the above requirements are not complied with by any component of the Class 2HA vessel, that component may be upgraded to comply in full with requirements for Class 1H vessel components, including the requirements for non-destructive examination, and a detailed fatigue analysis, in accordance with the requirements in (A) for Class 1H vessel components, shall be carried out.

NOTE: For Class 2HA vessels, it is permissible to upgrade a component or components to Class 1H requirements to satisfy local fatigue requirements.

(C) For Class 2HB vessels and vessel components — all components both integral and non-integral shall comply with the requirements specified in Clause S3.1.5.6, or as specified for non-integral parts in Clause S3.1.5.7, for parts that do not require a detailed fatigue analysis.

NOTE: For Class 2HB vessels, it is not permissible to upgrade a componentor componentsto Class 2HA or Class 1H requirements to satisfy local fatigue requirements.

3.1.5.5 Rules to determine need for a detailed fatigue analysis of integral parts of Class 1H vessels. A detailed fatigue analysis need not be made, provided that all of Condition A below or all of Condition B below is satisfied; a detailed fatigue analysis shall be made for those parts which do not satisfy the conditions. The following requirements are applicable to all integral parts of the vessels, including integrally reinforced type nozzles. For vessels having pad type nozzles or non-integral attachments, the requirements of Clause S3.1.5.6 apply. (a) Condition A. Condition A is applicable to both

ferrous and non-ferrous materials.

For Condition A, a detailed fatigue analysis is not mandatory where the material has a specified minimum tensile strength not exceeding 560 MPa for parts other than bolts (see Paragraph SC3 of Appendix SC for bolts), and where the total of the expected 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 and shutdown.

(ii) The expected number of operating pressure cycles in which the range of pressure variation exceeds 20 percent of the design pressure. The number of cycles in which the pressure variation does not exceed 20 percent of the design pressure shall be limited as follows except in unusual configurations with high stress concentration factors: (A) Ferrous materials — no limit.

(B) Non-ferrous materials — 106_cycles.

NOTE: Pressure cycles caused by fluctuations in atmospheric conditions need to be considered.

(iii) The effective number of changes in metal temperature* between any two adjacent points† in the pressure vessel, including nozzles. The effective number of such changes is determined by multiplying the number of changes in metal temperature of a certain magnitude by the factor given below, and by adding the resulting numbers. The factors are as follows:

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 protecti on devices, such as thermal sleeves in nozzles, may be used to reduce temperature dif ferences or thermal shock. † Adjacent points are defi ned as points which are spaced less than the distance 2 (Rt) fr om each other, where R and t are the mean radius

and thickness, respecti vely, of the vessel, nozzle, flange, or other component in which the points are located. (Expression 2 (Rt) does not apply to flat plates.)

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Example: Consider a design subject to the following metal temperature differentials and number of cycles:

∆t,°C Cycles

25 . . . 1000 50 . . . 250 220 . . . 5 The effective number of changes in metal temperature is —

1000(0) + 250(1) + 5(12) = 310

The number used as (iii) in performing the comparison with 1000 is then 310. Temperature cycles caused by fluctuations in atmospheric conditions need not be considered.

(iv) The number of temperature cycles which causes the value of (α₁-α₂)∆T to exceed 0.000 34 for components involving welds between materials having different coefficients of expansionwhere

α1andα2are the mean coefficients of thermal expansion and∆T is the operating temperature range.

NOTE: This does not apply to cladding (see Clause 3.3.1.2). Cladding should be the subject of a detailed analysis of thermal stresses.

(b) Condition B. Condition B is applicable only to those materials which are referred to in Appendix SC, i.e. apart from nickel-copper alloy, it is not applicable to non-ferrous materials.

For Condition B, detailed fatigue analysis is not mandatory where all the following conditions are satisfied:

(i) The expected (design) number of full-range pressure cycles, including start-up and shutdown, does not exceed the number of cycles in the applicable fatigue curve of Appendix SC corresponding to an Savalue of 3 times the f value found in Table S3.3.1 for the material at the operating temperature.

(ii) The expected (design) range of pressure cycles during normal operation* does not exceed 33 percent of the design pressure multiplied by S_a/f, where S_a is the value obtained from the applicable fatigue curve of Appendix SC for the specified number of significant pressure fluctuations and f is the design strength for the operating temperature. If the specified number of significant pressure fluctuations exceeds 106_, the Savalue at N = 10

6_{may be used.}

NOTE: Significant pressure fluctuations are those for which the range exceeds the quantity of 33 percent of the design pressure multiplied by S/f, where S = the value of

Safor 10 6

cycles.

(iii) The temperature difference between any two adjacent points† of the vessel during normal operation* and during start-up and shutdown operation does not exceed S_a/(2Eα), where S_ais the value obtained from the applicable design fatigue curve for the specified number of start-up and shutdown cycles, αis the value of the instantaneous coefficient of thermal expansion at the mean value of the temperature

at the two points, and E is the modulus of elasticity at the mean value of the temperatures at the two points.

(iv) The range of temperature difference between any two adjacent points* of the vessel does not change during normal operation† by more than the quantity Sa/(2Eα), where Sa is the value obtained from the applicable design fatigue curve for the total specified number of significant temperature difference fluctuations. A temperature difference fluctuation shall be considered to be significant if its total algebraic range exceeds the quantity S/(2Eα), where S is the value of Sa obtained from the applicable design curve for 106_cycles.

(v) For components fabricated from materials of differing moduli of elasticity or coefficient of thermal expansion or both, the total algebraic rangeof temperature fluctuation experienced by the vessel during normal operation does not exceed the magnitude —

S_a/[2(E₁α₁- E₂α₂)]

where Sa is the value obtained from the applicable design fatigue curve for the total specified number of significant temperature fluctuations, E1 and E2 are the moduli of elasticity, andα1andα2 are the values of the instantaneous coefficients of thermal expansion at the mean temperature value involved for the two materials of construction. A temperature fluctuation shall be considered to be significant if its total excursion exceeds the quantity —

S/[2(E1α1- E2α2)]

where S is the value of Sa obtained from the applicable design fatigue curve for 106cycles. If the two materials used have different applicable design fatigue curves, the lower value of S_ashall be used in applying the rules of this paragraph.

NOTE: This Clause does not apply to cladding (see Clause 3.3.1.2). Cladding should be the subject of a detailed analysis of thermal stresses.

(vi) The specified full range of mechanical loads, excluding pressure but including piping reactions, does not result in load stress intensities whose range exceeds the S_a value obtained from the applicable design fatigue curve for the total specified number of significant load fluctuations. If the total specifiednumberof significantload fluctuations exceeds 106_{, the S}

a value at N = 10

6_{may be} used. A load fluctuation shall be considered to be significant if the total excursion of load stress intensity exceeds the value of Saobtained from the applicable design fatigue curve for 106 cycles.

S3.1.5.6 Rules to determine need for fatigue analysis of nozzles with separate reinforcement and of non-integral attachments of Class 1H vessels. A fatigue analysis of pad type nozzles and non-integral attachments need not be made provided that all of Condition AP below or all of Condition BP below is satisfied.

* Normal operati on is defined as any set of operating conditi ons other than start -up and shutdown, which are specifi ed for the vessel to perf orm it s intended function.

† Adjacent points are defi ned as points which are spaced less than the distance 2 (Rt) fr om each other, where R and t are the mean radius and thickness, respecti vely, of the vessel, nozzle, fl ange, or other component in which the points are located. (Expression 2 (Rt) does not apply to flat plates.)

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In the application of Condition AP or Condition BP, all fillet welds and partial penetration welds are non-integral attachments except for the following:

(i) Welds connecting non-pressure parts not subject to significant cyclic loads or temperature variations and not closer to a gross structural discontinuity than —

where

D = i nt er na l di am et er at t he discontinuity of the shell where the attachment is welded. If a large nozzle is considered to be a discontinuity, the diameter of the nozzle is used if the attachment is welded to the nozzle wall, or the diameter of the vessel if the attachment is welded to the vessel. If a knuckle in a dished end is considered to be a discontinuity, the diameter of the dish at the knuckle, which will usually be the same as the vessel diameter, is used. ts = thickness of the shell where the

attachment is welded on

(ii) Welds for attachment of support skirts or other supports involving similar attachment orientation, where the effective throat dimension of the attachment weld is not less than the thickness of the attachment.

(a) Condition AP. Condition AP is applicable to both ferrous and non-ferrous materials.

For Condition AP, detailed fatigue analysis of pad type nozzles and non-integral attachments is not mandatory where the material has a specified minimum tensile strength not exceeding 560 MPa for parts other than bolts (see Paragraph SC3 of Appendix SC for bolts), and where the total of the expected 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 and shutdown.

(ii) The expected number of operating pressure cycles in which the range of pressure variation exceeds 15 percent of the design pressure. The number of cycles in which the pressure variation does not exceed 15 percent of the design pressure shall be limited as follows except in unusual configurations with very high stress concentration factors:

(1) Ferrous materials — no limit. (2) Non-ferrous materials — 106_cycles. NOTE: Pressure cycles caused by fluctuations in atmospheric conditions need not be considered. (iii) The effective number of changes in metal

temperature between any two adjacent points in the pressure vessel, including nozzles. In the calculation of the temperature difference between adjacent points, conductive heat transfer shall be considered only through welded or integral cross-sections with no allowance for conductive heat transfer across unwelded contact surfaces. The effective

number of changes is determined by multiplying the number of changes in metal temperature of a certain magnitude by the factor given below, and by adding the resulting 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 . . . 12 NOTES: 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 temperature differentials for the following number of times: ∆t,°C Cycles 25 . . . 1000

50 . . . 250

220 . . . 5 The effective number of changes in metal temperature is —

1000(0) + 250(1) + 5(12) = 310

The number used as (C) in performing the comparison with 400 is then 310.

(iv) The number of temperature cycles which causes the value of (α1 - α2)∆T to exceed 0.000 34 for components involving welds between materials having different coefficients of expansion, whereα1andα2are the mean coefficients of thermal expansion and ∆T is the operating temperature range.

NOTE: This does not apply to cladding (see Clause 3.3.1.2). Cladding should be the subject of a detailed analysis of thermal stresses.

(b) Condition BP. Condition BP is applicable only to those materials which are referred to in Appendix SC, i.e. apart from nickel-copper alloy, it is not applicable to non-ferrous materials.

For Condition BP, detailed fatigue analysis of pad type nozzles and non-integral attachments is not required where all the requirements of Clause S3.1.5.5(b) are satisfied by the following adjusted values:

(i) Use a value of 4 instead of 3 in Condition B(i).

(ii) Use a value of 25 percent instead of 33 percent in Condition B(ii).

(iii) Use a value of 2.7 instead of 2 in the denominator of Condition B(iii), (iv), and (v). S3.1.5.7 Alternative method for the determination of need for fatigue analysis of parts of vessel. This Clause (S3.1.5.7) provides an alternative to the method in Clauses S3.1.5.5 and S3.1.5.6 for determining the need for a detailed fatigue analysis of parts of a vessel. A detailed fatigue analysis of vessels or vessel components need not be made, provided that each part of the vessel complies with a relevant path in Figure S3.1.5.7.

NOTE: This method is technically equivalent to the method given in Clauses S3.1.5.5 and S3.1.5.6 but reference should also be made to these Clauses for additional information.

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FIGUR E S3.1.5.7 FLOW CH AR T FOR NEE D FOR DETAILED FATIGUE AN ALYS IS

TAB LE S3.1.5.7 VA LUES OFSa/N FOR PLOTTING IN DES IGN FATIGUE CUR VE S IN APP EN DIX SC

POINT Sa N= number of cycles

1 2 3 4 5 6 ef ef∆P/P eEα∆T/1.5 eEα∆T/1.5 e∆T(E₁α₁−E₂α₂)/1.5

∆S(mechanical other than above)

Full range pressure cycles including start up and shutdown Pressure cycles duri ng norm al operations whose range >S6P/ef

Start up and shutdown cycles

Temperature diff erence vari ation∆Twhose range > 1.5S6/ eEα

Temperature cycle whose range > 1.5S₆/ e(E₁α₁−E₂α₂)

Mechanical stresses (other than above) whoses stress intensity range <S₅

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The notation and calculation parameters used in this Clause are as follows:

E = modulus of elasticity at mean temperature of a part, in megapascals

E1, E2 = modulus of elasticity of two different materials welded together, in megapascals e = factor from Figure S3.1.5.7

F_i = temperature factors as follows

Metal temperature Factor (F_i) differential (∆T_i) ≤25 . . . 0 >25 ≤55 . . . 1 >55 ≤85 . . . 2 >85 ≤140 . . . 4 >140 ≤195 . . . 8 >195 ≤250 . . . 12 >250 . . . 20 f = material design strength, in megapascals N = number of cycles

N(_—) = number of cycles for a given condition N_D = expected (design) number of full range

pressure cycles including start-up and shutdown

N_F = ΣN_iF_i

Ni = number of changes in metal temperature difference between two points no more than 2 (Rt) apart for integral parts of vessels OR

= number of changes in metal temperature difference between any two adjacent points in the pressure vessel, including nozzles for non-integral parts

NT = number of temperature cycles which causes (α1 - α2)∆T to exceed 0.000 34 for parts of dissimilar metals welded together

P = design pressure, in megapascals

∆P = pressure variation amplitude, in megapascals R = mean radius of the vessel, nozzle, flange or

other component in which the points are located, in millimetres

R_m = specified minimum tensile strength of material at room temperature, in megapascals

S6 = Safor 10 6

cycles, in megapascals

Sa = stress amplitude from fatigue curve, in megapascals

∆S = stress amplitude from causes other than thermal stress and pressure, in megapascals T₁,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 of vessels, in degrees Celsius

OR

= temperature difference between any two adjacent points in the pressure vessel, including nozzles for non-integral parts (see Note), in degrees Celsius

t = thickness of the vessel, nozzle, flange or other component in which the points are located, in millimetres

α = instantaneous coefficient of thermal expansion at the mean temperature of two points less than 2 (Rt) apart, in reciprocal kelvins

α1,α2 = coefficient of thermal expansion of two different materials welded together, in reciprocal kelvins

NOTE: Conductive heat transfer is considered only through welded or integral cross-sections with no allowance for conductive heat transfer across unwelded contact surfaces.

S3.2 DESIGN CONDITIONS. Clause 3.2 applies, with the following additions and modifications to particular Clauses:

S3.2.2.3 Temperature fluctuations from normal conditions. Clause 3.2.2.3 does not apply to this Supplement and the following shall be substituted: Where temperature fluctuations from normal conditions occur, the vessel shall be designed in accordance with Clause S3.1.5.4.

S3.2.3 Loadings. Clause 3.2.3 applies except that the last paragraph 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) is required only where it is not possible to demonstrate the adequacy of the design, e.g. by comparison with the behaviour of comparable vessels.

The conditions under which a fatigue analysis that takes into account loadings (h) to (n) is not required are set out in Clauses S3.1.5.4 to S3.1.5.7.

S3.3 DESIGN STRENGTHS. Clause 3.3 applies with the following additions and modifications to particular Clauses:

NOTE: Within Clause 3.3 and where appropriate, substitute ‘design strength (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, except for the revised heading and with the following additions and modifications to particular Clauses:

S3.3.1.1 General. Clause 3.3.1.1 does not apply to this Supplement and the following shall be substituted: The design strength (f) values for materials other than bolting material, used in the construction of vessels to the requirements of this Supplement are given in Table S3.3.1. These values are based on the material properties (see Appendix SA) and —

(a) are the maximum values to be used in the equations presented by this Section for determining the minimum thickness (or other dimensions) of vessel parts; and

(b) form the basis for the various stress intensity limits which are specified in Table S3.1.5 and Appendix SH for loadings or components not covered by Section 3.

NOTE: Some design strength values listed in Table S3.3.1 may depart 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 where appropriate. The casting quality factor shall be 0.70 except that a higher factor of 0.90 may be used where this factor is justified by the additional testing required by Clause 5.9.

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For some vessels operating under special conditions and as required by the design, it may be desirable to adopt a reduced design strength to —

(a) limit deflection in close-fitting assemblies; (b) allow for corrosion fatigue or stress corrosion

conditions;

(c) allow for an exceptionally long life; or

(d) provide for other design conditions not intended to be covered by the stress criteria (see Clause S3.1.5). S3.3.1.3 Bolting. Where bolt tensioning procedures are established and detailed stress analysis of the bolted joint is made, the alternative higher stress values as given in ANSI/ASME BPV-VIII-2 may be used. In the absence of the above procedure and analysis, bolt strengths as listed 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 — design strength values shall be as listed in Table S3.3.1(i). (b) Other materials to Standards Australia specifications — for other steels and non-ferrous materials to Standards Australia specifications, design strength values are under consideration, but the design strength may be determined on the basis of Appendix SA or may be taken equal to the values of Table 3.3.1.

(c) Materials to BSI and ASTM specifications — design strength values shall be as specified in Table S3.3.1(ii).

TABLE S3.3.1(i)

DESIGN STRENGTH CARBON-MANGANESE STEEL PLATE TO AS 1548 Material type Standard No Grade (see Note) Group No

Thickness Design strength (f), MPa Temperature,°C mm 50 100 150 200 250 300 325 350 375 400 C-Mn AS 1548 5-490N,T A2 >16 >40 >80 ≤ ≤ ≤ ≤ 16 40 80 150 209 209 209 209 194 194 194 194 179 179 179 179 168 168 168 168 150 150 150 150 138 138 138 138 134 134 134 134 130 130 130 130 126 126 126 126 122 122 122 122 7-430R, N, T A1 >16 >40 >80 ≤ ≤ ≤ ≤ 16 40 80 150 183 183 180 167 169 167 165 151 154 151 148 135 139 138 135 130 124 124 124 124 110 110 110 110 108 108 108 108 105 105 105 105 102 102 102 102 99 99 99 99 7-460R, N, T A1 >16 >40 >80 ≤ ≤ ≤ ≤ 16 40 80 150 196 196 183 177 175 173 166 156 154 151 148 135 139 138 135 130 124 124 124 124 110 110 110 110 108 108 108 108 105 105 105 105 102 102 102 102 99 99 99 99 7-490R, N, T A2 >16 >40 >80 ≤ ≤ ≤ ≤ 16 40 80 150 209 207 200 187 187 184 180 172 165 162 160 156 150 148 146 142 132 132 132 132 120 120 120 120 117 117 117 117 114 114 114 114 111 111 111 111 108 108 108 108 5-490NH, TH A2 >16 >40 >80 ≤ ≤ ≤ ≤ 16 40 80 150 209 209 209 209 200 200 200 200 191 191 191 191 179 179 179 179 160 160 160 160 147 147 147 147 143 143 143 143 139 139 139 139 133 133 133 133 127 127 127 127 7-430RH, NH, TH A1 >16 >40 >80 ≤ ≤ ≤ ≤ 16 40 80 150 183 183 180 167 174 172 168 156 164 161 157 144 148 147 144 139 132 132 132 132 117 117 117 117 114 114 114 114 112 112 112 112 108 108 108 108 105 105 105 105 7-460RH, NH, TH A1 >16 >40 >80 ≤ ≤ ≤ ≤ 16 40 80 150 196 196 183 177 180 178 170 160 164 161 157 144 148 147 144 139 132 132 132 132 117 117 117 117 114 114 114 114 112 112 112 112 108 108 108 108 105 105 105 105 7-490RH, NH, TH A2 >16 >40 >80 ≤ ≤ ≤ ≤ 16 40 80 150 209 207 200 187 192 190 186 177 176 173 171 167 160 157 156 152 141 141 141 141 128 128 128 128 125 125 125 125 121 121 121 121 118 118 118 118 115 115 115 115 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 plate manufacturer 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 the otherwise 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 5500 for Category 1 vessels

Values equal to the ‘Design Strength Values’ specified in BS 5500

ASTM specifications —

Material types and grades specified in ANSI/ASME BPV-VIII-2

Values equal to the ‘Design Stress Intensity Values’ 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 and modifications.

S3.5.1 Welded joints. Clause 3.5.1 applies with the following additions and modifications to particular Clauses:

S3.5.1.7 Welded joint efficiency. Clause 3.5.1.7 applies except that for welded main longitudinal and circumferential joints of Class 2HA and Class 2HB vessels complying with the requirements of this Supplement, a joint efficiency of 1.0 may be used. Only joints having an efficiency of 1.0 shall be used for welded main joints.

S3.5.1.8 Butt-welding between plates of unequal thickness. Clause 3.5.1.8 does not apply to this Supplement and the following shall be substituted: If two plates are to be welded by a butt joint and differ in thickness by more than 25 percent of the thinner plate, or by more than 3 mm, the thicker plate shall be reduced as shown in Figure 3.5.1.8. In all such cases, the edge of the thicker plate shall be trimmed to a smooth taper extending for a distance of at least four times the offset between the abutting surfaces so that the adjoining edges will be approximately the same thickness. The length of the required taper may include the width of the weld. The maximum thickness through the weld shall be as given 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 AND SPHERICAL SHELLS SUBJECT TO INTERNAL PRESSU RE AND COMBINED LOADINGS. Clause 3.7 applies, with the following addition: For components of simple vessels not subject to additional external or internal loads and for which detailed fatigue analysis is not required by Clauses S3.1.5.4 to S3.1.5.7, the minimum thickness of cylindrical and spherical shells shall be calculated from the following equations:

For cylindrical shells —

t = . . . S3.7(1) For spherical shells —

t = . . . S3.7(2) Vessels or vessel components designed to resist additional loads or requiring detailed fatigue analysis shall be the subject of a detailed stress investigation. S3.8 THICK-WALLED CYLINDRICAL AND SPHERICAL SHELLS SUBJECT TO INTERNAL PRESSURE. Clause 3.8 applies, with the following additions:

For components of simple vessels not subject to additional external or internal loads and for which detailed fatigue analysis is not required by Clauses S3.1.5.4 to S3.1.5.7, the minimum thickness shall be calculated from equations given in Clause S3.7, except that where P > 0.4f the following equations may be used:

For cylindrical shells —

P = f log_e . . . S3.8(1) For spherical shells —

P = 2f loge . . . S3.8(2) logeis the natural logarithm, i.e. to the base e.

Vessels or vessel components designed to resist additional loads or requiring detailed fatigue analysis shall be the subject of a detailed stress investigation. S3.9 CYLINDRICAL AND SPHERICAL SHELLS SUBJECT TO EXTERNAL PRESSURE. Clause 3.9 applies in its entirety, including design strengths. S3.10 CONICAL ENDS AND REDUCERS SUBJECT TO INTERNAL PRESSURE. Clause 3.10 applies, with the following additions:

For simple vessels not subject to additional external or internal loads and for which detailed fatigue analysis is not required by Clauses S3.1.5.4 to S3.1.5.7, the minimum thickness of conical ends and reducers subject to internal pressure shall be determined in accordance with Clause 3.10, but with values for design strength from Table S3.3.1.

Vessels or vessel components designed to resist additional loads or requiring detailed fatigue analysis shall be the subject of a detailed stress investigation. S3.11 CONICAL ENDS AND REDUCERS SUBJECT TO EXTERNAL PRESSURE. Clause 3.11 applies in its entirety, including design strengths.

S3.12 DISHED ENDS SUBJECT TO INTERNAL PRESSURE. Clause 3.12 applies with the following addition and modifications:

For simple vessels or vessel components not subject to loads additional to the loads due to internal pressure, not requiring detailed fatigue analysis by Clauses S3.1.5.4 to S3.1.5.7 and of shapes covered in Clause S3.12.5, the minimum calculated thickness of dished ends shall be determined from Clause S3.12.5 in lieu of the requirements in Clause 3.12.5.

For other vessels or vessel components, dished ends shall be the subject of a detailed stress analysis.

NOTE: The design method given in Clause S3.12.5 and the methods for the design of ends in other relevant Standards which form part of the SAA Boiler Code are currently under review with the objective of having a consistent basis for the design of ends. In the meantime, designers should be aware that there are differences between these Standards.

S3.12.5 Thickness of ends.

(a) Torispherical ends. The minimum calculated thickness of torispherical ends shall be determined by Equation S3.12.5(1) or Equation S3.12.5(2) as follows:

(i) For ≥0.002 and ≤0.08 —

t = R × 10G _{. . . S3.12.5(1)} (ii) For > 0.08 —

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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 design temperature (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 than the outside diameter (Do) of the end.

The inside knuckle radius shall be not less than 6 percent of the outside diameter (Do) or 3 times the 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 calculated thickness for hemispherical ends shall comply with Clause S3.7 or S3.8 as appropriate. S3.13 DISHED ENDS SUBJECT TO EXTERNAL PRESSURE. Clause 3.13 applies in its entirety, including design strengths.

S3.14 DISHED ENDS — BOLTED SPHERICAL TYPE. Clause 3.14 applies, with the following addition:

For simple vessels not subject to additional external or internal loads and for which detailed fatigue analysis is not required by Clauses S3.1.5.4 to S3.1.5.7, the minimum thickness of dished ends of the bolted spherical type shall be determined in accordance with Clause 3.4, but with values for design strength from Table S3.3.1.

Vessels or vessel components designed to resist additional loads or requiring detailed fatigue analysis shall 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 be determined in accordance with Clause 3.15, but with values for design strength from Table S3.3.1. Where the ends are attached by welding, the welds shall be of the full penetration type.

Ends designed to resist additional loads or requiring detailed fatigue analysis shall be the subject of a detailed stress investigation.

S3.15.5 Internally fitted doors. Clause 3.15.5 applies, except that design strength from Table S3.3.1 may be used.

S3.16 STAYED FLAT ENDS AND SURFACES. Clause 3.16 applies, with the following addition: Stayed flat ends are frequently subject to internal force and deflection and therefore require a detailed analysis for assessment of the working stresses. For proven simple vessels that are not subject to large temperature differentials, stayed ends may be designed in accordance with Clause 3.16 with values for 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 accordance with Clause 3.17, except that the design strength from Table S3.3.1 may be used in conjunction with AS 3857. When adopting the TEMA method, the design strength from Table 3.3.1 shall be used. S3.18 OPENINGS AND REINFORCEMENT. Clause 3.18 excluding Clause 3.18.6 applies with the following addition and modification.

Design strengths from Table S3.3.1 may be used. Departures from the above ‘reinforcement’ requirements are permitted if supported by theoretical or experimental investigation or where sufficient practical experience has demonstrated the adequacy of an alternative design.

S3.18.6 Unreinforced openings. Clause 3.18.6 does not apply and the following shall be substituted: Circular openings are not required to have reinforcement other than that inherent in the construction where all of the following conditions apply as applicable:

(a) A single opening shall have a diameter d (see Clause 3.18.2) not exceeding 0.2 (R_mT₁), or if there are two or more openings within any circle of diameter 2.5 (R_mT₁) then the sum of the diameters of such unreinforced openings shall not exceed 0.25 (RmT1), where Rm is the mean radius of the shell or end at the location of the openings.

As 1210 Supplement 1 - Unfired Pressure Vessels - Advanced D

Australian Standard



Unfired pressure vessels —

Advanced design and

construction

Australian Standard



Unfired pressure vessels —

Advanced design and

construction

(Supplement to AS 1210—1989)

PREFACE

CONTENTS

FOREWORD

STANDARDS AUSTRALIA

Australian Standard

Unfired pressure vessels — Advanced design and construction

(Supplement to AS 1210—1989)

SECTION S1. SCOPE AND GENERAL REQUIREMENTS

SECTION S2. MATERIALS

SECTION S3. DESIGN