Date post: | 07-Apr-2018 |
Category: |
Documents |
Upload: | hdyoon3379891 |
View: | 215 times |
Download: | 0 times |
8/4/2019 →comparative_study_en_13445_-_asme_viii
http://slidepdf.com/reader/full/comparativestudyen13445-asmeviii 1/26
1
Comparative Study: EN 13445 –
ASME VIII
Workshop on the Pressure Equipment Directive
Bucharest, February, 2007
Dr. Reinhard PreissTÜV Austria
Krugerstrasse 16A-1015 Vienna, AustriaTel. +43 1 51407 6136e-mail: [email protected]
http://www.tuev.at
8/4/2019 →comparative_study_en_13445_-_asme_viii
http://slidepdf.com/reader/full/comparativestudyen13445-asmeviii 2/26
2
Introduction
Background: A harmonised standard related to a "NewApproach" Directive does give the manufacturer the advantageof the presumption of conformity to the Essential SafetyRequirements of the Directive itself, but to be accepted andapplied, it must also bring economic and/or technical
advantages.
This study compares the economic and non-economicimplications arising from the application of (a) EN 13445 and, (b)
the ASME Boiler & Pressure Vessel Code plus major relatedcodes when appropriate (TEMA, WRC Bulletins), for the design,manufacture, inspection and acceptance testing of 9 benchmarkexamples of unfired pressure vessels.
8/4/2019 →comparative_study_en_13445_-_asme_viii
http://slidepdf.com/reader/full/comparativestudyen13445-asmeviii 3/26
3
Introduction
The consortium which carried out the study, based on acontract with the EC / DG Enterprise, consists of TUV Austriaand of Consorzio Europeo di Certificazione (CEC) – both areNotified Bodies according to the PED.
The detailed design of the benchmark examples wasperformed by the consortium. To evaluate the economicfactors concerning individual and/or serial production of thebenchmark vessels, pressure equipment manufacturers from
Italy, France, Germany and Austria took part assubcontractors.
8/4/2019 →comparative_study_en_13445_-_asme_viii
http://slidepdf.com/reader/full/comparativestudyen13445-asmeviii 4/26
4
Benchmark Examples - Overview
8/4/2019 →comparative_study_en_13445_-_asme_viii
http://slidepdf.com/reader/full/comparativestudyen13445-asmeviii 5/265
Benchmark Examples - Overview
8/4/2019 →comparative_study_en_13445_-_asme_viii
http://slidepdf.com/reader/full/comparativestudyen13445-asmeviii 6/266
Conformity Assessment
For estimation of the costs the following combinations of codes and conformity
assessment routes were considered:
EN 13445 and conformity assessment according to the PED (CE-marking).·
ASME Section VIII (Division 1, Division 2 if applied) and conformityassessment according to ASME (U-stamp, or U2-stamp).
ASME Section VIII (Division 1, Division 2 if applied) and conformity
assessment according to the PED (CE-marking).
The exercise is based on compliance with the corresponding requirements in a
situation where there are no pre-existing qualifications or supplementary data
which could be used from other similar equipment
8/4/2019 →comparative_study_en_13445_-_asme_viii
http://slidepdf.com/reader/full/comparativestudyen13445-asmeviii 7/267
Conformity Assessment
In the case of application ASME Section VIII (Division 1, Division 2 if applied) and
conformity assessment according to the PED additional requirements were made: Materials: material properties used in the design must be those affirmed by the
material manufacturer. This may include hot tensile properties (yield strength
according to ASME II Table Y-1), impact properties for carbon steel at MDMT but
not higher than 20°C with a minimum value of 27J.
Hydrostatic test Pressure: The hydraulic test pressure Ptest shall not be smaller
than 1.43 PS, even if this requires an increase in wall thickness when an
“equivalent design pressure Peq” given by Peq = Ptest x S/Sa /1,3 is greater than
PS. The 1.25x.. requirement is not used, but if it would be the governing one, the
NDT level is increased to at least 0.85.
Permanent joining and NDT: welding operating procedures and personnel, NDT
personnel: requirements as given in the PED have to be fulfilled
Fatigue design: ASME unconservative for welded regions?
8/4/2019 →comparative_study_en_13445_-_asme_viii
http://slidepdf.com/reader/full/comparativestudyen13445-asmeviii 8/268
Benchmark Example 1 – CNG Storage Tank
8/4/2019 →comparative_study_en_13445_-_asme_viii
http://slidepdf.com/reader/full/comparativestudyen13445-asmeviii 9/269
Benchmark Example 1 – CNG storage tank
DBA according to EN 13445 is advantageous in this case
Higher costs for the ASME design are basically caused by highermaterial costs, due to larger wall thicknesses, and to some extent
by the post weld heat treatment costs. A vessel according toASME VIII Div.2 is considerably cheaper than one according toASME VIII Div.1 due to the large differences in resulting wallthicknesses .
8/4/2019 →comparative_study_en_13445_-_asme_viii
http://slidepdf.com/reader/full/comparativestudyen13445-asmeviii 10/2610
Benchmark Example 1 – CNG storage tank
No considerable cost differences due to NDT
Test coupons required for EN design, but not for ASME. Thus,higher costs for EN for this task.
The additional costs for the ASME vessels if conformityassessment with the PED is required are rather small (somemarginally increased wall thicknesses for ASME VIII Div.1, highertesting requirements for the materials) – presuming that theresults of the material tests fulfil the requirements. In the case ofASME VIII Div. 2, no increase of the wall thicknesses due tohydraulic test pressure given by the PED is required.
8/4/2019 →comparative_study_en_13445_-_asme_viii
http://slidepdf.com/reader/full/comparativestudyen13445-asmeviii 11/26
11
Benchmark Example 2 –
Hydrogen Reactor
Diameter 2200 mm, cylindrical length app.
8000 mm, hemispherical ends, max.allowable pressure 180 bar, max.allowable temperature 400°C.
Forged courses: 11CrMo9-10 / EN 10222-2; SA-387 Gr. 22 Cl. 2.
Welded courses: 12CrMo9-10 / EN10028-2; SA-336 Gr. 22 Cl. 2.
8/4/2019 →comparative_study_en_13445_-_asme_viii
http://slidepdf.com/reader/full/comparativestudyen13445-asmeviii 12/26
12
Benchmark Example 2 – Hydrogen Reactor
Differences in the design wall thicknesses (e.g. for the main cylindrical
shell / forged courses 190 mm for EN 13445 DBF, 181 mm for ASME VIII
Div.1, and 151 mm for ASME VIII Div. 2; and for the main cylindrical shell / welded courses 124 mm for EN 13445 DBF, 181 mm for ASME VIII
Div.1, and 151 mm for ASME VIII Div. 2) are mainly caused by the
different allowable stresses.
8/4/2019 →comparative_study_en_13445_-_asme_viii
http://slidepdf.com/reader/full/comparativestudyen13445-asmeviii 13/26
13
Benchmark Example 2 – Hydrogen Reactor
The costs are do mainly depend on the wall thicknesses, thereare no considerable cost differences due to NDT, and testcoupons required for both routes.
Again, the additional costs for the ASME vessels if conformityassessment with the PED is required are rather small (somemarginally increased wall thicknesses for ASME VIII Div.1, highertesting requirements for the materials) – presuming that theresults of the material tests fulfil the requirements. In the case of
ASME VIII Div. 2, no increase of the wall thicknesses due tohydraulic test pressure given by the PED is required.
8/4/2019 →comparative_study_en_13445_-_asme_viii
http://slidepdf.com/reader/full/comparativestudyen13445-asmeviii 14/26
14
Benchmark Example 4 – Stirring Vessel
8/4/2019 →comparative_study_en_13445_-_asme_viii
http://slidepdf.com/reader/full/comparativestudyen13445-asmeviii 15/26
15
Benchmark Example 4 – Stirring Vessel
A fatigue analysis was performed for the fluctuating load components of the stirrer,
considering a requirement of an infinite number of load cycles. A fatigue analysis for the
upper end, leading to the allowable number of (specified) batch cycles, was also
performed.
The fatigue results differ substantially: the required reinforcement of the mounting
flange to obtain stresses which result in a design for an infinite number of load cycles is
different for the two code routes. Furthermore, the allowable number of batch cycles
according to EN is 13100, but that according to ASME is 2x108.
8/4/2019 →comparative_study_en_13445_-_asme_viii
http://slidepdf.com/reader/full/comparativestudyen13445-asmeviii 16/26
16
Benchmark Example 4 – Stirring Vessel
Since the material SA-240 Grade 316Ti is not allowed for application of
ASME VIII Div. 2, and the allowable stress of SA 240 Grade 316L is
considerably lower, the application of ASME VIII Div. 2 would generally lead
to larger wall thicknesses for the shells and ends. Thus, application of ASME
VIII Div. 2 is not economic in this case.Inner body of the vessel: differences in the design wall thicknessess are
mainly caused by different design methods for external pressure (EN design:
11 mm wall thickness, two reinforcing rings 25x125 mm; ASME design:
15 mm wall thickness, two reinforcing rings 30x160 mm). Inner dished end:
differences in the design wall thicknessess also mainly caused by the
different design methods for external pressure (EN design: 15 mm wall
thickness; ASME design: 23 mm wall thickness).
8/4/2019 →comparative_study_en_13445_-_asme_viii
http://slidepdf.com/reader/full/comparativestudyen13445-asmeviii 17/26
17
Benchmark Example 4 – Stirring Vessel
The higher costs for the ASME designs are basically caused by higher material costs
due to larger wall thicknesses, and thus higher fabrication costs. These are partly
compensated by lower costs for NDT and for test coupons, since the NDT
requirements according to ASME are lower than those according to EN (for the
chosen weld joint efficiency) and due to the fact that no test coupons are required forthe ASME route.
The additional costs for the ASME vessels if PED conformity assessment is required
are rather small and are mainly caused by higher material costs due to the required
increased wall thickness for the lower end and the costs for an additionally required
pad at a nozzle. Due to the moderate service temperature no hot tensile test is
required, and no additional impact testing is considered necessary for the austenitic
steels used. Thus, the additional costs for material testing are negligible.
8/4/2019 →comparative_study_en_13445_-_asme_viii
http://slidepdf.com/reader/full/comparativestudyen13445-asmeviii 18/26
18
Overall Summary
The project has considered application of the new harmonisedstandard EN 13445 and the ASME VIII design procedures to a setof 9 example cases which covered a wide range of pressurevessel types, designs, materials and fabrications .
The overall basis for comparison was one of economic cost. Aprocedure was used which allowed fair comparison of threeroutes: EN 13445, ASME + U-stamp, ASME + PED. While theconsortium performed the design, several EU manufacturers wereinvolved in the project to assess the costs.
8/4/2019 →comparative_study_en_13445_-_asme_viii
http://slidepdf.com/reader/full/comparativestudyen13445-asmeviii 19/26
19
Overall Summary – Cost Comparison Table
8/4/2019 →comparative_study_en_13445_-_asme_viii
http://slidepdf.com/reader/full/comparativestudyen13445-asmeviii 20/26
20
Overall Summary
Material costs are frequently greater using the ASME code. In somecases, savings attributable to lower material costs with EN 13445 arepartly offset by additional costs of weld testing and NDT when comparedwith ASME requirements.
For standard refinery heat exchangers no notable costs differences arereported (if TEMA requirements are considered).
In some cases the reported costs differences for different manufacturersare larger than the cost differences resulting from the application of thevarious code routes.
PWHT costs are frequently higher for ASME design, since the PWHTrequirements depend on the wall thicknesses.
8/4/2019 →comparative_study_en_13445_-_asme_viii
http://slidepdf.com/reader/full/comparativestudyen13445-asmeviii 21/26
21
Overall Summary
Use of Design-by-Analysis according to EN 13445-3 Annex B candecrease the material costs considerable in some cases, especially formore advanced or complex design or in serial production. Theincreased design costs are easily compensated by the savings formaterials and – if applicable – by the savings of the post weld heattreatment costs.
According to the cost estimations of the manufacturers, the extra costsfor ASME designs to meet the PED requirements are in general small
for the approach used in the study.
8/4/2019 →comparative_study_en_13445_-_asme_viii
http://slidepdf.com/reader/full/comparativestudyen13445-asmeviii 22/26
22
Overall Summary
Fatigue design according to ASME Div. VIII Sec. 2 Appendix 5 forwelded regions is considered to be non-conservative in comparisonwith procedures in major European pressure vessel codes (e.g. EN13445, AD-Merkblatt, PD 5500) and the underlying experimental
results. Thus, ASME fatigue design for these regions is not consideredto meet the requirements of PED Annex I. Taking this into account, theresults of alternative design procedures may be required for fatigueevaluation, i.e. re-assessment of the fatigue life using a Europeanapproach would be desirable in practice, but was not performed within
this study.
8/4/2019 →comparative_study_en_13445_-_asme_viii
http://slidepdf.com/reader/full/comparativestudyen13445-asmeviii 23/26
23
Discussion on ASME reply
According to the paper “Design Fatigue Life Comparison of ASME Sec.VIII and EN 13445 vessels with welded region” by Kalnins et.al. ([1],PVP 2006-ICPVT-11) fatigue strength reduction factors shall be used,
e.g. the ones given in WRC Bulletin 432. In the opinion of the authors ofthe Comparative study, in the ASME code itself this is stated for filletweld but no there is no hint to use such factors for full penetration welds.In a mayor code, it should be stated unambiguous if such factors shallbe used and also the reference where to find such factors shall be
given.
8/4/2019 →comparative_study_en_13445_-_asme_viii
http://slidepdf.com/reader/full/comparativestudyen13445-asmeviii 24/26
24
Discussion on ASME reply
According to the paper “Comparison of Pressure Vessel Codes ASMESection VII & EN 13445” by Antalffy et.al. ([2], PVP 2006-ICPVT-11) thevessel manufacturers providing cost estimates in the study are not basedin countries which produce the majority of pressure vessels in the world
(Japan, Korea, USA).According to [2], the size and quantity distribution of vessels used in the
Comparative Study is generally not representative of typical chemical,petrochemical or petroleum process facilities. The greater part of thetotal cost of pressure vessels is attributed to only a relatively smallnumber of the higher end pressure vessels. For these high end vesselsASME Section VIII Div. 3 can be used, which reduces wall thickness andcost by up to 15 percent over present Division 2 requirements.
8/4/2019 →comparative_study_en_13445_-_asme_viii
http://slidepdf.com/reader/full/comparativestudyen13445-asmeviii 25/26
25
Discussion on ASME reply
According to [2] a review of the EN standard has shown several important and
innovative features. The ASME is in the process of rewriting Section VIII, Division
2, which will make a range of Division 2 vessels even more competitive with the
EN standard. This rewrite is an opportunity to incorporate the latest advances in
pressure vessel design, as well as new and innovative features that will enable
the ASME Code to remain the preeminent pressure vessel standard.
The survey presented in [2] concluded that throughout the global industry there
is a strong preference to use the ASME codes for pressure vessel design and
manufacturing. Even though the PD5500 or EN 13445 may have a few specific
areas or cases where there is a small economic advantage, when consideringthe overall aspects of the entire organization, plant, or project cost, the ASME
code seems to provide a better overall advantage.
8/4/2019 →comparative_study_en_13445_-_asme_viii
http://slidepdf.com/reader/full/comparativestudyen13445-asmeviii 26/26
26
Comparative Study: EN 13445 –
ASME VIII
Thank you for your attention !
Questions and comments welcome !