ASME VIII-2 training 1

[ilovechickens]

I am thinking of attending a training course run by Codeware on ASME VIII-2 and I was wondering if anyone out there has attended this course and has any comments on it.

I am especially interested in understanding more about allowable nozzle loads on vessels as I am fed up getting information on drawings when I am designing piping systems that says:

"allowable nozzle loads are Fx, Fy, Fz = 10000N Mx, My, Mz = 5000Nm"

To me this does not really help me very much as it seems pretty vague - what about occasional loads? what if I have a load of -8000N?

I am keen to learn more and I am wondering if this training course will help me do so.

 

[doberdorks]

Well, my opinion is that the course would help you learn more, but not help with what you appear to want to learn.

Personally I'd LOVE to get the information you list -- better than the "zero" or "dead silence" that I normally get for allowable loads.

In your case, I'd just ask the vendor -- it's really more of a case of "who owns this" than "what is the science behind this"....

A course on VIII-2 will tell you how to build a vessel to VIII-2, not "why did the vendor give me this load and what does it mean".

SLH

 

[vesselguy]

I have not attended a Codeware ASME Sect VIII-Div2 course. But, I have attended the Div. 2 course offered by ASME with Mr. Mokhtarian and I would recommend it.

http://catalog.asme.org/Education/OnlineInstructorLeadCourse/Section_VIII_Division_2.cfm

You do know that Div. 2, nor does Div. 1, governs nozzle loads or tell you how to analysis it. So, if that's your aim the couse might not help you. Although, by attending the course, Mr. Mokhtarian will suggest what you should do, so you might be able to get something out of it. Better yet, if nozzle loads is what you want then you should read up on WRC-107 or use Nozzle-Pro.

I gather from your post that you're a piping designer? If so then you should be giving your piping load to the Fabricator or your vessel engineer to check the shell stresses. The set of allowable loads you posted is only for guidence purpose;actually it is kind of useless. Always have your shell stresses calculated for each set of piping loads.

 

[TomBarsh]

Kam Mohktarian (Code committee member) teaches the same courses for ASME, Codeware, and a few other providers (outside the USA). Kam is an extremely knowledgeble and experienced gentleman.

But I'm not certain that the Div 2 course is what you need. You may want to see what Paulin Research Group (PRG) offers, particularly their internet-based Webinars. See

http://www.paulin.com/webinar/Default.aspx.

PRG publishes the FE/Pipe and NozzlePro software, among other things. Tony Paulin is one of the original developers of the CAESAR II (Coade) piping analysis program.

Their list of webinar courses changes over time but several webinars have been specifically devoted to piping load issues and resolving problems at the interface between the vessel and piping.


Tom Barsh
Codeware

 

[dig1]

I agree with Tom Barsh. I have taken the latest Div. 2 class with Kam and this will really not answer your specific question. The Paulin courses or Webinars address this much better.

The Div. 2 course is excellent but with so much information to cover in 4 days this is really not an area that can be covered in depth.

 

[ilovechickens]

Thank you for your comments everyone. I appreciate them. From the feedback received this is an excellant course but given the 4 day timeframe specific topics (e.g.nozzle loads) can not be covered in great depth.

I too often get stunned slience when asking pressure vessel suppliers about nozzle loads, or sometimes told that the nozzles can take minimal load (so don't lean on one you might break it).

I am primarily a piping designer although I design pressure vessels as well. I do use Nozzlepro for checking the vessel nozzle loads.

We do put allowable nozzle loads on our vessel drawings but I do not believe that when we do so we are always clear about what we are in fact specifying.

For example If I specify Fx Fy Fz, = +-10KN and Mx, My, Mz =+-5KNm then unless I run all possible combinations of the
loads with the different signs in Nozzlepro (about 36 possible combinations I believe?) then I am not sure that we have checked the complete spectrum of allowable loads to make sure the nozzle is OK.

We do make intelligent (I hope they are anyway) deductions based on geometry and direction of nozzle loads to minimise the number of combinations of loads that we need to run in nozzle pro but I am keen to find out more about dealing with nozzle loads correctly when we are designing our vessel, which was one of the areas I was keen to cover in the ASME VIII-2 course.

 

[ilovechickens]

I have tuned into a couple of the Paulin Webinairs on piping related topics but given the short timescale of these webonairs again it is diffult for topics to be covered in any great depth.

I will have another look at the courses thay are running re nozzle pro etc and see what they cover and if I think they will cover in more detail the information I am looking for.

We do sometimes use WRC-107 to check the nozzle loads however our geometry more often than not falls outside the limits of WRC-107.

 

[dig1]

If you take the 2 day NozzlePro course this topic is covered in more detail. Patrick Marcotte does a good job going over this, at least he did when I took the course.

 

[LSThill]

Team Members:
Additional Technical detail information
Regards to NozzlePro PRG Software: Saddle Wizard, High Temp/Creep, API 579 FFS, API 661, Piping Runs

What is NozzlePRO?

NozzlePRO is a component analysis tool for piping and pressure vessels. The tool brings the accuracy of the finite element method to the engineering community for general design and analysis. NozzlePRO is based on the technology offered in FE/Pipe with a user interface that simplifies input and allows engineers to quickly analyze piping and pressure components with a high degree of accuracy.

NozzlePRO technology is a significant improvement over the limitations inherent in WRC 107/297 methods. WRC methods are accurate across a small subset of ranges found in industrial applications. Since NozzlePRO is based on the finite element method, there are application constraints based on geometry.

Evaluate nozzles, saddles, pipe shoes and clips on shell or heads. Modeled head types include...
Conical
Dished
Elliptical
Spherical
Inputs include thermal, weight, operating, occasional, pressure, wind and earthquake loads as well as material and nozzle orientation. NozzlePRO includes the Saddle Wizard and has interfaces with MatPRO, COMPRESS, and Microprotol.

What are key NozzlePRO features?
Automated nozzle calculations: allowable loads, flexibility factors, stress intensification factors
Automatic fatigue calculations for piping and pressure vessel codes
Extend use of piping programs beyond B31 flexibility and SIF limits on D/T (B31.3, Appendix D)
Fatigue analysis includes a calculation for maximum allowed cycles and includes fatigue analysis according to BS5500, EN13445, ASME and WRC 474.

Improve beam analysis in piping programs using flexibility factors (WRC 329)

Interface with MatPRO allows comprehensive ASME material property lookup
Nozzle reinforcements: barrel and pad reinforced
Rich DirectX graphics show animated models for each load case and code stress category
Saddle wizard with pipe shoe options for repads, fluid head, tapered saddles, and user controlled boundary conditions
State and transient heat transfer analysis of selected head models
Tabular and graphical reports are produced in HTML.

B31J Standard Test Method for Determining Stress Intensification Factors (SIF or "I-Factors") for Metallic Piping Components – 2008 Edition (Publication Date: May 30, 2008)

What is FE-SIF?
Classical pipe stress analysis programs use piping beam elements that are constrained to the limitations inherent with beam elements. For example, beam elements do not capture the effect of ovalization where the cross section of the pipe deforms away from the unloaded round geometry.

To compensate for the limitations, correction factors are applied to the beam models to more closely match the flexibility and stresses of the pipe to reality. The correction factors, flexibilities and stress intensification factors (SIFs), are based on analytical and empirical relations correlated to piping component geometries. The accuracy of the correlations depends on the geometries of the piping components.

FE-SIF brings finite element analysis (FEA) to the piping designer's toolkit to provide accurate SIF and flexibility factor calculations for all geometries and load conditions. FE-SIF can be used to calculate correction factors for components outside the correlational limits of standardized design codes and for components with no guidance in the design codes

What is FE107?

What is wrong with WRC 107 and WRC 297?

WRC 107 and WRC 297 are very good documents for engineering practice. It is based on an analytical treatment of openings in cylindrical shell and hemispherical heads. This said, there are fundamental assumptions in WRC 107 and correlations that are used in the correlations that limit the application of WRC 107 in industrial applications. Commonly, computer programs do not provide warnings or guidance when the limitations are violated.

In general WRC 107 comparisons to FE/Pipe results are excellent when thin shells are analyzed and when the model is within the accepted parameters of WRC 107. Nozzles in the centers of heads are evaluated most accurately. Most WRC 107 programs give the stress intensity at four points around the nozzle on both the inside and outside of the geometry. This stress is usually compared to 3Sm (Sm is the average of the hot and cold allowable stress) and is caused by all operating loads on the nozzle. The resulting stresses from a WRC 107 run of this type should be compared to the Pl+Pb+Q stresses from the finite element calculation. Note that Pl stresses evaluated in accordance with ASME Section VIII Division 2 are membrane stresses. These are the average stresses through the thickness and do not include the bending stress component at the junction. (See ASME Section VIII Division 2 Appendix 4 Table 4-120.1.)

WRC 297 comparisons in the vessel or header tend to be good but become overly conservative when the high stress moves into the branch when the t/T ratio becomes less than 1.0. This result is certainly demonstrated in the finite element calculation.

WRC 107 tends to be somewhat less conservative than finite element results, but that WRC 107 results parallel FE calculations through d/D ranges of 0.1 to 0.8, where the WRC and Finite element curves cross, the WRC 107 results becoming much more conservative beyond this range. (When the approach used outside of WRC curve parameters is “last curve value.”)

The following list summarizes areas where WRC 107 and WRC 297 are considered weak, or where there is cause for concern.
d/D > 0.5
t/T > 1.0
Pad reinforced nozzles
Hillsides or laterals

Area replacement rules for pressure are barely satisfied and large diameter divided by thickness ration (D/T).
Temperatures are approaching the creep regime.
Cycles are greater than 5000.

Design and operating conditions are approximately the same.
The load consists of high-pressure stresses and high loads.
The Piping attached to the nozzle is long, flexible, and somewhat unrestrained.



John Breen, Becht Engineering (Mechanical): Mr. Leonard S. Thill is a Senior Engineer who is very respected in the engineering community, 17 June 2007.


L S THILL

 

[Cheops]

vesselguy,

You indicated that you attended the Online course by Dr. Mokhtarian. Do you actually listen to his voice or do you have to read the material? I am interested to attend, but only if I would listen to his course. If I have to read, then I may as well read the Code myself.

Thanks,