anybody has input the value of the stiffness of the nozzle in a pump.
peng hasa paper with a formula to calculate this value, but it is an error use this value to determiate the forces and moment in a pump nozzle?

I did not find the reference in Peng and Peng's book.

Exactly what flexibility are you thinking about ? Have you considered shaft alignment, coupling/ bearing wear or even internal rubbing in the pump ?

If you look at a typical API pump set-up, the weakest and most flexible part is usually the frame and pedestal.

I would recommend stick to rigid body modelling and limit loads to the usual API or similar allowables.

This reference is in the www.pipestress.com, it is a web o peng, and here is a technical paper, called: Rethinking the Allowable Pipe Load on Rotating Equipment Nozzles.

I agree with MoverZ. We always assume the pump body is rigid. Also refer to WRC 449 Guidelines for the Design and Installation of Pump Piping Systems. It states normal practice is to assume pump body is rigid, and if any pump nozzle flexibility is to be considered, the stiffness values shall be provided by the pump vendor and the effect on pump nozzle allowables shall be considered. I've never asked a pump vendor for nozzle flexibilities, but based on my experience with equipment vendors, I think most, is asked, would respond "rigid".

thanks a lot guys, i apreciate your help.
i have modeled the nozzles of a pump, and input the value of the stiffness, obtaining forces and moments too low in suction and discharge.
however this is very difficult to believe that will be real.