Hi all,

I have some confusion as to which report to use for checking the nozzle loads on a centrifugal pump. I've read and understand CAESAR's distinction between global coordinates (only on nodes) and local coordinates (elements). My issue is as follows:

1. From a logical point of view if the piping system ties in to the pump at say node 10, and I've placed an anchor at node 10 to simulate that connection (I'm aware of the common practice to model nozzle connections with rigid elements with zero weight) then a global restrain report (Fx, Fy, Fz...) should be all I need to see the piping system's influence at that nozzle point. Correct? Or simply run the report option for "local restrains" ?

2. When I run the module for API 610 or use the Nozzle Lmt Check option the report shows local coordinates (fx, fy, fz...). I understand that these modules are converting the piping forces (global) to the point of reference of the pump and that is why it is being reported as local but it doesn't make a great deal of sense to me.

In conclusion, for pump nozzle loads do you look at local reports or global? From reading all the CAESAR literature it seems straight forward that the nozzle connection is a node therefore one MUST look at the global report and not local report (elements).

Please help clarify this confusion I'm having !

Thank you in advance

Don't confuse CAESAR II local coordinates and API 610 local coordinates - they need not be the same.
Your system's global coordinates will give you the proper alignment between the CAESAR II results and pump orientation. I would say global coordinates offer the most complete reference.

Dave thank you, global it is and I'm glad to see that it is as I figured (hoped) !

I do have one follow up question...why then does the "Nozzle Lmt Check" option report show results in local coordinates (fx, fy, fz...)?

The way I understand the "Nozzle Lmt Check" option is that it functions as a "bookmark" to the specific nodes and a one to one comparison to "this is your allowable" and "this is what you are getting"...you are over the limit or below, that's it. If that understanding is correct, then the report should be in global (Fx, Fy, Fz...)

Thank you

The Nozzle Limit Check now found in the CAESAR II input (as opposed to the stand-alone API 610 check) requires the definition of a "reference axis" (B) with respect to the piping system's global coordinate system. A similar reference is established in that stand-alone processor as well.
These equipment checks are always with respect to a THEIR local coordinate system and that always has to be related, in some way, to the CAESAR II global coordinates. The local, piping system reports are with respect to the piping or restraints in the model so the program, of course, handles that translation directly.