Hi to all,
I used WRC/107/297 in caesar II to evaluate nozzle. I finished input the required data field in the input spread sheet. After running the file, I access ANALYSIS->WRC107/297 in main menu and input data for vessel and nozzle. When I Access the output for SUSTAIN, it appears zero load, why? also for EXPANSION & OCCASIONAL LOAD the field are DISABLE, WHY?

Can anybody help to solve my query?

It would be faster if you just sent your WRC input file in to techsupport@coade.com

Thanks Richard Ay,
I already sent my file to technical support of coade.
In relation to my post, I have additional query regarding the limitations stated in WRC 297. In my case, Dn/Tn (=18.098) < 20 which is not valid to thin-shell theory. It was also stated in the bulletin that the exact limit of application depends on the Dn/Tn ratio.
Where;
Dn= Outside diameter of the vessel.
Tn= Wall thickness of the vessel.
The following are my questions:
1. Does it mean WRC 297 it not applicable in the case I'ved analyzed?
2. How about the rest of those limitaions if not meet, still WRC 297 is not applicable?
3. Caesar II Provide only a warning not an error. Do I need to continue my analysis?

1) It means the authors did not run any tests outside of the published limits, so your results could be applicable, or they could be very wrong.

2) Same answer as for #1.

3) This is where engineering judgement and experience come into play. If we made this an error, then a Dn/Tn ratio of 19.999 would halt the analysis. Would you really want that?

Sorry for diameter and thickness description in my previous post, Dn=Diameter for the nozzle & Tn=Thickness for the nozzle.
If the authors did not run any test outside of the published limit, then how they arrived those limitations?

Based on the results generated from Caesar II, using WRC 297, How would I know that the vessel is safe?

In addition to my questions, In WRC 107 file, under Vessel Data-> Analysis type in which three analysis types are availabe but only WRC 107 and WRC 297 available to select.
1. If I will select WRC 297, what calculation results that are not covered by WRC 107?
2. Using WRC 297, under Loads Data tab What specific load case do I get the output is it OPE output, or SUSTAIN output, or EXPANSION output,?

Please share your knowledge..

Nald,

I would recommend that you read bulletins WRC-107 and WRC-297 and understand its range and limitations. CAESAR II is just implementing what is written in these bulletins.

When you are out of range of these bulletins the results are less accurate. This depends upon how much you are out of their range. This is where you engineering experience and judgment comes (you also can go and ask a senior engineer)

How much are your stresses. If you are a little out of the range and your stresses are half of the allowable then you are probably ok.

If all this fails then you can go to finite element analysis and evaluate the stresses.

WRC 297 only addresses cylinder to cylinder intersections. At this time we have input for only 1 set of loads in WRC-297. You have to put all the loads in one block. WRC 297 also provides stresses in nozzle wall in addition to the shell.

WRC 107 covers cylindrical, square or rectangular attachment on cylinders and spheres (only square and round). You can enter load in sustained, expansion and occasional categories.

I hope this helps.

Mandeep Singh,
Thank you very much sir..
It sad to know that most of our senoirs have limited knowledge regarding this bulletin..
As you stated "At this time we have input for only 1 set of loads in WRC-297. You have to put all the loads in one block".
So we have to generate report for SUSTAIN, EXPANSION & OCCASIONAL independently?

Hello Nald,

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 and FE107 from PAULIN RESEARCH GROUP, bring 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. You can click on link below to find out more about this issue.

http://www.paulin.com/WEBfe107-1.aspx

Dear Richard Ay,
Supposed I want to use analysis WRC 107/297 in CAESAR II mean menu, is it always necessary to model the nozzle under nozzle modeling WRC107/297 in the spread sheet so that the stiffnesses will be considered in the analysis?

By modeling the WRC297 stiffnesses in the piping model, the loads at the nozzle (induced by the piping) are lowered. If you model the nozzle as an anchor, the loads will be higher.

Once you have performed the flexibility analysis, you can then take the loads at the nozzle and perform the WRC107/297 evaluation of the nozzle itself. Part of the setup for this analysis is the input of the piping loads, obtained from the flexibility analysis.

So therefore in order to get a feel of accuracy and conservative stress calculated results I will performed two analysis, one with flexibilities and one without flexibilities..

Another query regarding the two options of load specification under Loads Data tab (Global CAESAR II convention and Local WRC 107 Convention) in WRC107/297 analysis. Supposed I will input the nozzle loads manually by using Local WRC 107 Convention. Since vessel and nozzle directions are disabled in this convention,How does CAESAR II program knows the vessel direction vector and nozzle direction vector?

Why would it need the vectors when you tell it explicitly according to the WRC107 convention, which force is which and the same for moments? A radial force is just that... it doesn't require any direction cosines. The same goes for each of the 6 loads you input.

Thank you very much sir..

Why not "Operating Forces" are taken in parallel to sustained and expansion loads in WRC 297/107 analysis?

Regards

CAESAR II WRC 297 report does not directly show Pm(SUS) and Pl(SUS) unlike WRC CAESAR 107 report . Then how we can compare the values of WRC 297 report with the allowables as per ASME VIII Div II...?

Sir Richard Ay kindly help.

Regards

If the loads that you entering are sustained (pressure and weight) then compare the stress intensities to 1.5*S.

If the loads are thermal or a combination of sustained and thermal then use approx 2S.

Also run WRC-107 and perform nozzle reinforcement calcs

At this time we do not ask the user about what kinds of loads are entered so we cannot perform the comparison to the allowables. It is on the development list.

Is it possible to have some printscreened example wherein is carried out the said Analysis of WRC 107; practically still there is left confusion as to whether take nozzle node, whereat WRC loads are to be applied, as an anchor or model it as a nozzle while building model of piping system.

Regards,

Muhammad Imran Mirza

Dear Richard Ay,

I have additional query related to the WRC-107 load application,

There are three load case required for WRC 107, they are sustained, expansion (thermal) and occasional loads (Relief valve load).

My question is how to get the value for expansion loads and occasional loads for WRC 107 analysis (i.e.) am i have to select the operating load case (W+P1+T1) or expansion load case (T1) as an input for WRC-107 expansion case and similarly operating load case (W+P1+T1+F1 relief valve load) or occasional load case (F1) as an input for WRC-107 occasional case.

Please clarify...