Brief understanding of ASME VIII Div.2
Brief understanding of ASME VIII Div.2
(OP)
Never having used ASME VIII Div.2 could somebody please explain what it provides. I understand that it allows a more precise analysis of the stresses inherent in a vessel, but is this done solely by finite element analysis or are equations provided as an alternative?





RE: Brief understanding of ASME VIII Div.2
Pressure Limit up to 3000 psig for Div. 1, and no upper limit for Div. 2;
Safety Factor: 3.5 for 1 and 3 for 2;
Design Rule: maximum membrane stress for 1, and maximum shear stress for 2;
NDE: may be exempted for 1, and much more stringent for 2;
PE Certificate: normally not required for 1, and required for 2;
Hudrotest pressure: 1.3 for 1 and 1.25 for 2;
Code Stamp: U with many additional for 1, and U2 with additional HT only;
...... and so on,
In addition, an very important feature in Division 2 pressure vessel is the determination of whether a fatigue analysis is required for the expected operating conditions of the vessel. Under paragraph AG-301, ¡°It is the user¡¯s responsibility to specify, or cause to be specified, whether or not a fatigue analysis of the vessel shall be made¡±. If required, the Manufacturer¡¯s Design Report shall include the analysis in accordance with paragraph AG-302.2.
RE: Brief understanding of ASME VIII Div.2
Thanks for the reply, could you please clarify what you mean by a PE certificate.
Thanks.
RE: Brief understanding of ASME VIII Div.2
Below is the OUTLINE of USER DESIGN SPECIFICATION
RE: NBIC/ANSI 23
VESSEL ITEM NUMBER:
UDS-
Rev.
SERVICE:
OPERATING TEMPERATURE CYCLE: °F(°C) TO °F(°C) HOURS
OPERATING PRESSURE CYCLE: PSIG (Kg/cm2g) TO PSIG (Kg/cm2g) HOURS
CYCLIC: SERVICE: ( ) YES ( ) NO
FATIGUE ANALYSIS: ( ) REQUIRED ( ) NOT REQUIRED
VESSEL OPERATION SATISFIED AD-160.1: ( ) YES ( ) NO ( ) UNKNOWN
VESSEL OPERATING SATISFIED AD-160.2 AND AD-160.3: ( ) YES ( ) NO
CORROSION/EROSION ALLOWANCE: IN. (mm)
NORMAL OPERATING PRESSURE: P.S.I.(Kg/cm2g)
NORMAL OPERATING TEMPERATURE: EF (EC)
SUPPORT TYPE: ( ) SKIRT, ( ) LUGS, ( ) LEGS
LIQUID CONTAIN:
GAS CONTAIN:
LETHAL SERVICE: ( ) YES ( ) NO
MATERIAL:
WIND LOADING PER:
EARTHQUAKE PER:
WEIGHT OF INTERNALS:
AM-204, AD-155.1, AF-402, APPLY: ( ) YES ( ) NO
ITEM TITLE TO BE DESIGNED, CONSTRUCTED, TESTED
AND CERTIFIED IN ACCORDANCE WITH ASME SECTION VIII DIVISION II EDITION
WITH ADDENDA AND IN COMPLIANCE WITH USER'S DESIGN SPECIFICATION.
USER:
USER'S AGENT:
PREPARED BY:
P.E. STAMP NO.:
Leonard@thill.biz
www.thill.biz
RE: Brief understanding of ASME VIII Div.2
Samuelliu's response was pretty good. I'll take two exceptions, though. There is no upper limit on the pressure for a Div. 1 vessel. U-1(j) clearly states that although the rules of Div. 1 have been formulated for pressures not exceeding 3000 psi, and "deviations from and additions to these rules usually are necessary...", "... if the vessel still complies with all of the requirements of this Division..." it may be stamped with the Code symbol. Usually, however, vessels with such high design pressures will have more thorough engineering and QA/QC anyway, so it makes sense to explore Div. 2 or Div. 3 (keep in mind the limited availability of Div. 3 fabricators).
Secondly, fatigue issues are not exclusive to Div. 2. Division 2 provides guidance for evaluating fatigue which is not available in Div. 1, but a Div. 1 vessel must still be evaluated. See UG-22: "The loadings to be considered in designing a vessel shall include those from:...(e) cyclic and dynamic reactions due to pressure or thermal variations, or from equipment mounted on a vessel, and mechanical loadings;..." Since Div. 1 requires fatigue analysis but doesn't provide guidance on how to accomplish this, often a Div. 2 fatigue analysis will be used for a Div. 1 vessel.
Division 2, in AG-301.2 states that "A Professional Engineer, registered in one or more of the states of the USA or the provinces of Canada, and experienced in pressure vessel design, shall certify..." the Users Design Spec. In general, a P.E. has a certain amount of education and/or experience, has passed an Engineer in Training (EIT), or more modernly, a Fundamentals of Engineering (FE) test in general engineering principles, and has passed a Professional Engineering test in a specific field such as Mechanical or Civil.
To answer a part of your question directly, Div. 2 provides formulas similar to Div. 1 for designing vessels. Finite element analysis is ocassionally used as a design tool also, in which case reference is made to Appendix 4. FEA is supplemental to the formulas given in the main body of the Division. If Div. 2 provides a formula (for example for the required for a 2:1 SE head), then FEA may not be used to reduce the thickness provided by that formula. Another example would be nozzle reinforcement required for internal pressure (but not for piping loads). Using FEA to show that less reinforcement is necessary than called out in the AD-520 would not meet the requirements of the Division.
jt
RE: Brief understanding of ASME VIII Div.2
I agree with jte (Mechanical)and the reference to FEA
The easy way to do ASME SECTION VIII: DIV.2 AND DIV.3 IS
http://www.paulin.com/newprg/products.htm
FE/Pipe Template based Finite Element modeling with ASME code checking for nearly any piping or pressure vessel problem.
FE/Pipe
In contrast to traditional finite element modeling, where the analyst must build the model from scratch, FE/PIPE uses pre-fabricated templates for piping and vessel components. A library of component templates is available for Piping Intersections, Nozzles (in Flat Plates, Cones, Tanks, Heads, including Hillside Nozzles), Reinforcing Pads, Stanchions on bends, Piping Supports, Lugs, etc. The Shell String Modeler allows one to model connected Piping and Vessel segments. This includes mitered elbows, bends, reducing elbows, cylindrical and conical segments, annular plates, and spherical or elliptical heads. The latest version includes templates for a shell containing multiple nozzles, a pad reinforced fabricated cross, structural elements, and API storage tanks, nozzles and base settlement. The Plate Processor allows user defined plate attachments (lugs, saddles, shoes etc) for shell and nozzle elements. Large complex geometries may be built up by combining several smaller "child" models to a "parent" model. This is done by defining common nodes between models. The recent addition of 8-node Brick Templates allows one to perform thick wall (D/t < 10) analysis. 32-bit processing and graphics have speeded up the program by 2-3 times. There is also automated animation, Quick Calc feature for WRC107/297 and N318/392, a thermal profiler for unreinforced fabricated tees, and reinforcing pad options for hillside nozzles and bends with stanchions.
What are specific areas where a FEPipe calculation is needed? In summary, the following examples illustrate areas where FEPipe can significantly improve on existing more simplified design methods.
- Validation of pressure designs in large d/D intersections
- Allowable load determination on nozzles.
- Replacement Method for WRC 107 or WRC 297
- Cyclic applications (>5000 cycles)
- Large hillside or lateral nozzles.
- Nozzles subject to high temperatures and the potential for elastic follow-up. (>800 deg.F)
- Transverse or Axial loads on saddles.
- Bends with staunchions or structural weldments
- Transient Thermal (and thermal+pressure) loading conditions.
- Stiff systems interacting
- SIF's for non-code geometries, or for geometries outside of Code limits, and geometries not addressed by the code.
- Jacketed Piping systems
- Fixed tubesheet designs
- Collapse of thin walled piping geometries
- Stress distributions around multiple openings
FEPipe is a template driven finite element program designed exclusively for the piping and petrochemical markets. FEPipe handles saddles for axial or lateral loads, a result that Zick could never do, and find stresses in lugs and attachments in the automodeller. FE/Pipe will also produce allowable loads on nozzles which can then be handed to the piping engineer for evaluation. The new version FEPipe 4.100 does a spectacular job with multiple, close proximity nozzles in heads or cylinders using unstructured meshing.
It's known that B31 Appendix D is only justified for D/T<100. For thin walled pipe, FE/Pipe is the only tool available that will make a direct calculation of the sif and flexibility. FE/Pipe handles the thermal gradient requirements of 301.7.2, and the cyclic load requirements of 301.10. This is where the real failures occur and if the structure cycles then an accurate calculation of the loads and stresses is important. If your work involves API 579 the required membrane and bending stress determinations are found directly in FE/Pipe using Pl and Qb as described by Bergreen. You can even incorporate patches of localized corrosion/erosion and dents.
Yes! better then a pice of cake
Leonard@thill.biz
www.thill.biz
RE: Brief understanding of ASME VIII Div.2
I have made this point before and upset some people and I don't wish to do that again, especially bearing in mind the kind & concise responses I've received.
But I'm not in the USA, and the vessels I'm designing aren't destined for the USA.
In the UK we don't have Professional Engineer status, instead we have Chartered Engineers.
Could someone clarify how this relates to the code.
Fawkes
RE: Brief understanding of ASME VIII Div.2
I got the feeling that you weren't in the USA or Canada, but wasn't sure. The best thing for you to do is check with the local authorities where the vessel will be fabricated and installed. Another option is to contact a large Engineering and Construction firm and take one of their engineers out to lunch and find out what they do. I don't have contacts in England anymore, but you might want to get in touch with someone at the Fluor Daniel office in Camberly (FD also has an office in London, but I'm under the impression they don't do PV work).
Clearly, some interpretation is required. It sounds possible that the Chartered Engineer label may meet the intent of the Code where a PE is called for. Probably the main advantages, from a public protection perspective, of having a PE involved with the design, are that the engineer is forced to have at least some experience in the field (not 2 months out of college and designing a 700 psi at 1000°F reactor) and also that the PE license is revocable. A BS degree is not revocable. Thus if a major error causes major damage, the PE license can be pulled by the state. Someone holding only a university degree has less to lose. If the Chartered Engineer designation has similar requirements as a PE (university degree + experience), then philosophically at least it seems to be in line with the intent of the Code.
jt
RE: Brief understanding of ASME VIII Div.2
I agree with jte (Mechanical) and The following individuals/firms are available as independent contractors for pressure vessel and related work.
http://www.codeware.com/consult.html
Leonard@thil.biz
www.thill.biz
RE: Brief understanding of ASME VIII Div.2
sect VIII div 2 often results in a thinner walled vessel( compared to div 1), in return for more detailed calculations. Although one can use FEA with div 2, Div 2 was developed in the 1960's assuming the use of manual calculations,so if a component is designed with FEA, one has the added chore of converting the detailed stresses from FEA into the somewhat cruder categories required for a sect VIII div 2 review. Sect VIII div 2 is scheduled for a major revision this yeat, and may be more FEA friendly. For a comparison of EN13445 vs sect VIII div 2, see recent works by Alain Handtschoewercker (google search), such as "assembly of information on European Standards development ( CEN) relevant to pressure equipment fatigue design" final report , july 2001
RE: Brief understanding of ASME VIII Div.2
Finite elements analysis is an alternative to those equations found in the ASME Codes. Although these ASME equations are not short cut, to use them will not require reams of computer data as you would get with finite analysis to build pressure vessels. Obviously ASME equations will be more conservative.
RE: Brief understanding of ASME VIII Div.2
RE: Brief understanding of ASME VIII Div.2
I just returned from the 2003 ASME Pressure Vessels and Piping (PVP) Conference in Cleveland. One of the papers presented related to this issue: "An Overview of the New ASME Section VIII, Division 2 Pressure Vessel Code" by David Osage, page 219 of PVP volume 453. The paper simply states that one of the new features will be an "Alternative to US RPE (Registered Professional Engineer) requirement." Part of the reason to attend the conference is to hear the papers presented and gain some additional insight into them. In this case, the author mentioned that the PE requirement was recognized as a barrier to the use of Div. 2 internationally which is why the alternative is being offered. What that alternative is, though, was not explained, and will probably be modified as the draft works its way through the Code Committee. None the less, it is good to see that issues such as this are recognized as barriers for international use and are being dealt with.
jt