1、 Guidance on the specification of Pressure vessels PUBLICATION 211 Edition 2 RELEASED BY IHS. NOT FOR RESALE THE ENGINEERING EQUIPMENT AND MATERIALS USERS ASSOCIATION Guidance on the specification of Pressure vessels PUBLICATION 211 Edition 2 Copyright 2014 The Engineering Equipment and Materials Us
2、ers Association. A company limited by guarantee. Registered in England. Company number 477838. ISBN 978-0-85931-201-1 Imprint reference 2-2014 Registered and Trading Address 63 Mark Lane London EC3R 7NQ Telephone: +44 (0)20 7488 0801 Fax: +44 (0)20 7488 3499 E-mail: saleseemua.org Website: www.eemua
3、.org EEMUA Publication 211 - Guidance on the specification of pressure vessels EEMUA ii ENGINEERING EQUIPMENT AND MATERIALS USERS ASSOCIATION About EEMUA The Engineering Equipment and Materials Users Association is usually known by its initials, EEMUA. EEMUA is an Association established by the owne
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20、UA Publication 211 - Guidance on the specification of pressure vessels EEMUA iv EEMUA Publication 211 - Guidance on the specification of pressure vessels EEMUA v Contents Overview vii 1. Considerations on the avoidance of repeat post-weld heat treatment 1 1.1 Introduction . 1 1.2 Exemptions from PWH
21、T given in the codes . 1 1.2.1 When PWHT is a code requirement 1 1.2.2 When PWHT is a service requirement . 3 1.2.3 Further aspects . 4 1.2.4 General requirements for welds where PWHT is waived 5 1.3 Example from the power industry . 6 2. Design for exceptional internal pressure 7 2.1 Introduction .
22、 7 2.1.1 Assumptions . 7 2.2 Design methods 8 2.2.1 Service levels 8 2.2.2 Simple design method 8 2.2.3 Advanced design method . 9 2.3 Testing 10 2.4 Comparison with EN 14460 10 2.5 Further information on containment of exceptional pressures . 11 3. Minimum nozzle loadings and nozzle design 13 3.1 I
23、ntroduction . 13 3.2 Minimum design nozzle loadings . 13 3.2.1 General 13 3.2.2 Vessels in ferritic steels, austenitic steels, duplex SS or nickel alloys . 14 3.2.3 Vessels in glass reinforced plastic 16 3.3 Minimum pipe schedule and standout for nozzles made from pipe . 16 3.3.1 Minimum pipe schedu
24、le 16 3.3.2 Nozzle standout 17 3.4 Small bore nozzle design . 17 4. Evaluating creep damage to pressure equipment . 19 4.1 Introduction/purpose . 19 4.2 Affected materials . 20 4.3 Critical factors 21 4. 4 Design approach 22 4.4.1 Boiler codes 23 4.5 Guidance on assessment of creep damage . 23 4.5.1
25、 Basis of assessment. 24 4.5.2 Assessment of creep 24 4.5.3 Data required . 26 4.5.4 Design /FFS Codes . 27 4.6 Inspection 28 4.6.1 Inspection techniques 30 4.7 Repairs 31 References . 35 EEMUA Publication 211 - Guidance on the specification of pressure vessels EEMUA vi Figures Figure 1 Loading conv
26、ention . 14 Figure 2 Design of NPS 1 (DN 25) or NPS 1 (DN 40) nozzles 18 Figure 3 Header with Serious Creep Damage 19 Figure 4 Uniaxial strain under constant load . 20 Figure 5 Classic and Omega model creep curves . 25 Figure 6 Creep Bulging under internal pressure . 29 Figure 7 Tube rupture caused
27、by short-term overheating . 29 Figure 8 Location of creep induced cracking in welds . 30 Figure 9 Susceptibility to cracking in aged HAZs 32 Tables Table 1 Maximum thickness which may be welded without PWHT for vessels operating above 0C 2 Table 2 Requirement for repeat PWHT on clips welded to vesse
28、ls 3 Table 3 Advanced assessment methods for Levels 1 and 2 based on non-linear behaviour (limit load) 10 Table 4 Class 150/Class 300 nozzle design loads with the vessel design pressure not exceeding 3 bar g 14 Table 5 Class 150/Class 300 nozzle design loads with design pressure greater than 3 bar g
29、 . 15 Table 6 Class 600 nozzle design loads 15 Table 7 Class 900 nozzle design loads 15 Table 8 Minimum design nozzle loadings for vessels in glass reinforced plastic 16 Table 9 Minimum pipe schedule and standout for nozzles made from ferritic steel pipe . 17 Table 10 Creep threshold temperature for
30、 various materials . 21 Table 11 An example of Miners Rule . 25 EEMUA Publication 211 - Guidance on the specification of pressure vessels EEMUA vii Overview The purpose of this Publication is to provide guidance on the specification of pressure vessels for circumstances not addressed in design codes
31、. Additionally, this Publication aims to compare international standards, particularly those from the USA, with UK and European equivalents. It has been prepared by the Pressure Vessels Committee (PRV) of EEMUA, the Engineering Equipment and Materials Users Association. As such, this Publication bri
32、ngs together the practical lessons learnt about design, manufacturing and testing of pressure vessels by users in EEMUA member companies. EEMUA 211 is composed of four Chapters: 1. Considerations on the avoidance of repeat post-weld heat treatment Post-weld heat treatment (PWHT) may be of considerab
33、le importance to the structural integrity of a pressure vessel. This Chapter examines the circumstances under which repeat PWHT may be waived. 2. Design for exceptional internal pressure This Chapter describes methods for assessing both existing and new pressure vessels for exceptional internal pres
34、sures. Simple and advanced design methods are provided for two levels of service performance. 3. Minimum nozzle loadings and nozzle design There are three sections to this Chapter which all relate to improvement in the specification and reliability of nozzles. In the first, tables of minimum design
35、loadings are provided to ensure that nozzles, made in steel, nickel alloys or glass reinforced plastics, are suitable for certain minimum loadings. In the second, requirements on standout and minimum pipe schedule are given for nozzles made from pipe. In the third, particular designs of small bore n
36、ozzles are specified. 4. Evaluating creep damage to pressure equipment This Chapter gives a basic appreciation of creep and how to assess situations where creep is suspected. It primarily intended to be used in relation to pressure vessels and similar equipment but does not specifically address pipi
37、ng where additional factors influence its design and assessment. EEMUA Publication 211 - Guidance on the specification of pressure vessels EEMUA viii EEMUA Publication 211 - Guidance on the specification of pressure vessels EEMUA 1 1. Considerations on the avoidance of repeat post-weld heat treatmen
38、t 1.1 Introduction Post-weld heat treatment (PWHT) relieves the residual stress at welds. It is beneficial in avoiding brittle fracture (for which the design codes give rules) and environmentally assisted cracking (for which purchasers determine requirements). In fabricating new equipment, PWHT may
39、be planned into the manufacturing process and is generally very cost effective. However, with existing vessels, carrying out repeat PWHT may present many practical difficulties. There may be restrictions at the site on keeping the components hot over the length of time needed. It may be difficult or
40、 impossible to provide sufficient heat. Undertaking PWHT in an oven, which is the standard practice for new fabrication, may not be feasible. The disturbance to adjacent equipment caused by carrying out PWHT may also be unacceptable. Occasionally the need may arise to weld on a vessel after its orig
41、inal fabrication and heat treatment has been completed. Such a welding operation might be necessary almost immediately, before or during commissioning the vessel, due to a design change; however, the need is more likely to occur in-service. New clips or studs may be needed for insulation supports or
42、 new anchors for fire-proofing materials. Components such as doubler plates or nozzles may be needed because of corrosion, or due to a process or mechanical design change. Overlay welding may be necessary to build up the thickness of a corroded part. In the extreme, for a major modification, a full
43、circumferential butt-weld may be needed. This Chapter indicates the thicknesses of components on which the codes currently permit welding without PWHT. It also discusses the welding techniques by which welds on thicker components can be made without repeat PWHT. It applies predominantly to vessels m
44、ade in ferritic (i.e. carbon, carbon manganese or low alloy) steels. 1.2 Exemptions from PWHT given in the codes 1.2.1 When PWHT is a code requirement 1.2.1.1 Main pressure parts For avoidance of brittle fracture, PWHT is usually specified for a given material above a certain thickness in the codes.
45、 Table 1 overleaf indicates the maximum thicknesses of components which may be welded without PWHT for vessels operating above 0C in accordance with ASME VIII Div. 1(1)or BSI PD 5500(2). The rules apply particularly to new vessels, but are also a major influence when the feasibility of modifying exi
46、sting vessels is under review. Table 1 applies to the greater thickness of the two components being welded. A vessel may have been given PWHT because of the thickness of the main plates, but it may be that the proposed modification is on a component with a thickness less than that shown in Table 1 o
47、verleaf. For example, if the modification is to a nozzle and the wall thickness of the nozzle is less than that in Table 1, welding to the nozzle - a new flange for example - is permissible without repeat PWHT. Care EEMUA Publication 211 - Guidance on the specification of pressure vessels EEMUA 2 sh
48、ould be taken that the length of the nozzle is such that the heat of welding does not affect the shell. The flange itself should be checked for the need for PWHT and rules are given in the codes for determining the nominal thickness for resistance to brittle fracture of different components, e.g. fl
49、anges and compensation pads. Table 1 Maximum thickness which may be welded without PWHT for vessels operating above 0C Code Material ASME P1/ BSI PD 5500 Band M0 or given PWHT to avoid process side environmentally assisted cracking (see Section 1.2.2); or subjected to PWHT because of code requirements to avoid brittle fracture. The requirement for repeat PWHT is given in Table 2 as either a YES or a NO. EEMUA Publication 211 - Guidance on the specification of pressure vessels EEMUA 3 Table 2 Requirement for repeat PWHT on clips we
