Greetings,

Please clarify me on the following for large diameter storage tank connected piping stress analysis:

1. Which soil settlement [edge] value should be used for nozzle displacement in the analysis? i.e. elastic settlement or consolidation settlement or total settlement.

2. If spring hanger is used then its design should be cold balanced or hot balanced?

Thank you

Hi,

It all depends on which type of analysis you are doing. If you are performing a analysis for new piping that will be attached to a tank which is already settel, then you can ignore this and calculate only future settlement if expected.

If you ask me then I will go with the total settlement and bulit up the load cases, considering the settlement as not a sustained but a secondary load, this effect need to be considered when your pipe is cold & hot.

For large tank with bottom nozzle, it will always try to rotate (when tank is fully filled with content) so there will be considerable amount of rotation which need to be consider when analysing the large tank with bottom nozzle. This you can calculate from API-650 appendix P.

About the spring I will recommend to check the spring design in the case where your pipe is hot with nozzle displacement and settlement. You will get the maximum load in this case and deflection as well.

Comments are welcome.

Regards,
R.K.

Check with your client if the storage tank piping is always filled or if it is emptied after loading/unloading. If so, you have to check with empty pipe also. This will make a lot of a difference because of the missing weight of the fluid. This is also important for determining the cold/installation load. If the spring gets unblocked with an empty line the load will be much less than when it is unblocked with a filled line.