Hi,

I have a question regarding API 650 11th edition appendix P and max allowed loads that Caesar compute them based on our input data.
when i compare calculated piping nozzel load with max. allowed loads, i can not pass them but when i calculate max stress from piping nozzle loads based on alternative procedure for evaluation of external loads on tank shell openings(API 650, P.3) and compare it with allowable stress, i can pass them.

which comparison is OK? and what are the differences between them?

Thanks in advance

To begin with, CAESAR II does not give you the maximum allowed loads on API-650 nozzles. What CAESAR II gives you are the limits for the two Interaction Diagrams from Appendix P. You must construct these figures and plot the nozzle loads (i.e. the restraint loads from your CAESAR II run) on these figures. If the point plots inside the figure, the nozzle is acceptable for those loads. If the point plots outside the figure, the nozzle/loads are unacceptable.

Be very careful with Section P.3, it has a number of errors.

Standards may provide rules (like these nozzle loads) that, when followed by both vendor and user, produce safe equipment operation. These standards may also allow exceptions when more rigorous analysis methods are used. So here, while the rules may fail, the more rigorous analysis proves the system safe.

You might want to look in the first few paragraphs of API 650 to see if they allow more rigorous analysis.

NUMBER OF ERRORS! COULD YOU PLEASE EXPLAIN THEM? I AM USING IT RIGHT NOW, WHAT SHOULD I DO?

P.3 has been removed from the later Editions/Addenda of API-650. Don't use P.3.

What about the 2007 version of this paper:

Analysis of Loads for Nozzles in API 650 Tanks
J. Pressure Vessel Technol. -- August 2007 -- Volume 129, Issue 3, 474 (8 pages)
doi:10.1115/1.2748829 -Lengsfeld, ..

I think P.3 was based on 2001 version of the paper.
??
If its not suitable, the only way to work on this subject is FEM, am I correct?

Hemn..

Ask Vendor for allowable loads (they mostly have with them the allowable...this lessens your worries to search for allowable)!!

FEM or Nozzle pro may be the last resort !!!