Appendix P

[99491]

In Appendix P of API 650 is the calculation indicated in the solution of the sample problem P.2.9 a constant or does it change ie. 3.1 x 10^-4. Is this fixed for each calculation or is it calculated and thus changes each time.

 

[gr2vessels]

99491,
The stiffness coefficients vary with the tank / nozzle configuration and you have to calculate these coefficients for your particular tank and nozzle configuration. That is, the 3.1 x 10^-4 is not a generic constant, but is determined from the graph P-2G for this particular nozzle with its reinforcing available only in the nozzle neck. The Appx. P seems at the beginning like rocket science, but after a careful reading of entire Appendix and a few practice calcs, following closely the examples, you'll see how easy it gets.
Happy practice to you.
Cheers,
gr2vessels