Tank Settlement Stress 1

[Crusader911]

I'm about to do stress analysis on some piping connecting to a new API 650 tank. I am planning on modeling the piping in Caesar II or Auto Pipe, and making the face of the flange of the nozzle a displaced anchor to account for settlement. I'm thinking there should be hot and cold installed cases (based on predicted settlement after staged loading) and hot and cold displaced cases (based on future estimated displacement). I will then take the restraint loads at the face of the nozzle flange for each of these cases and feed them to Nozzle Pro. Am I missing anything?

 

[DSB123]

Crusader911,
Yes you are missing something. You need to consder not only the settlement displacements but also the "bulging" of the tank wall by including the nozzle stiffnesses (Radial and Longitudinal rotational) and the radial and rotational displacement of the nozzle.

 

[Crusader911]

Thank you. I'm familiar with that effect, but I'm not sure how to model that. I don't know if Nozzle Pro or FE/Pipe can do that.

 

[richay]

If you define the nozzle as an API-650 nozzle in CAESAR II, then CAESAR II will compute and insert the nozzle stiffnesses (computed according to Appendix P) into your piping model. The software also gives you the deflection and rotation of the nozzle. If you want to include that in your analysis, apply these values to the CNODE on the nozzle. I would suggest you put your settlement displacement in a separate vector so you can setup load cases with or without it.

Once you get the nozzle loads from the CAESAR II analysis, you can qualify the nozzle using FE/Pipe or by manually drawing the figures from Appendix P.2.

Richard Ay
COADE, Inc.