We have several recirc pumps that have large loads being placed on the discharge and suction nozzles. The client wants the pumps put on springs. How do I model the pump to get the combined loads/displacements at the two nozzles?

Personally I would never place a piece of equipment on springs if piping loads are too high.
If I see your attachment I think you can get the nozzle loads correct by placing/changing supporting. However I only see a very small piece of the piping system of course.
For the combined loads in 1 node you need to use rigids and maybe also c-nodes. The use of c-nodes depends on whether or not you have modelled the pomp with rigids.
Are you really sure you have to check the combined nozzle loads?

Dear Egcollis,

Specify pump base node with an anchor, then use 2 RIGIDS from base node to suction and discharge nodes. Now here is your pump with 2 nozzles. Model suction and discharge lines from these nodes. You may also use anchor + CNODE to attach pipes to rigid elements. Then use API 610 pump analysis in CAESAR II to check pump loads.

Dear Egcollis,

I think you can control your piping loads by putting spring in discharge line near nozzle in horizontal spool and change first support in suction nozzle to spring.

Attached is the pump in question. I can compute combined vertical spring stiffnesses and equavlent bending stiffness, but how do I deal with horizontal stiffnesses?

Rule of thumb for simple springs shown is K vert = K horiz, but talk with (Google) Amber / Booth springs in Houston, Texas and see what they say.