Hello Everyone,

I get different results from CAESAR API-650 nozzle check and my hand calculation and decided to check the API example in CII.
Now I am checking API-650 (P.2.9.1 sample problem) nozzle results in CII (Version.12) against the API-650 example and they are not consistent. The snapshot of input and computed values in CII file is attached. The deflection and rotation of nozzle matches with API but stiffnesses and the AXIS limits don't match. Would you please tell me what I'm missing here?

Thanks

My information might be outdated, but I think CAESAR uses an older version of API-650 appendix P.

Which version of API-650 are you referencing?

Thank, Maybe. I'm using API-650-2013 issue but I just checked the 2007 version and that doesn't match either.

There are several problems with the example in Appendix P:

1) When pulling values from the curves, the example doesn't interpolate, it just uses the closest value. CAESAR II and TANK interpolate between the curves in the figures P2-A thru P2-F.

2) There is a set of curves for L/2a=1.0 (P2-A thru P2-C) and another set for L/2a=1.5 (P2-D thru P2-F). The example does not interpolate between these two sets of curves - say when L/2a=1.25. CAESAR II and TANK interpolate between these two sets of figures.

3) Intermediate results are rounded in the example. CAESAR II and TANK do not round values.

Thank you Richard,

That can answer the stiffness inconsistency but I think doing the backward calculation from CII output results, YF/C/L should be close to the graph values. Please correct me if I'm wrong but I think YC/L can be calculated from CII output as:

YC= Lambda*MC Limit/(a*FP*(1-0.75(Xc/(Rt)^0.5))= 1.31
YL= Lambda*ML Limit/(a*FP*(1-0.75(XA/B/(Rt)^0.5))= 0.59

Considering Lambda as 0.26, the calculated values are far off from the graph values (YF is close enough). Would you tell me what the reason is?

Thanks

Be careful with those limits, they each assume the other values are zero. This is why to qualify the nozzle you need to plot the (diamond and triangle) graphs, and plot the actual point (representing the nozzle loads).

Thanks Richard,

Yes, limits assume the other value is Zero and that's why it should give me the right YC/L/F values based on the M and F max(limits) the mentioned formulas (as they are not dependent on the other value). Please let me know if I'm missing something here?

Hi Charlot

When I last did a calculation a while back I found that there was error in the API 650 Example calculation printed in the code book. The calculation done on Caesar II and Tank is correct.

I cannot remember now exactly where it was in the code book example calc as it was a while back.

Go through the code book example thoroughly and you will find where the mistake is in the code book.

Thank you
Best Regards
Ryan Martin

Thank you Ryan