API 650 Tank Nozzle Loads

This may be more appropriate for the piping section since it refers to CAESAR rather than TANK, but it relates to API 650.

I am using CAESAR II to analyze the piping from two API 650 storage tanks. The tanks are 80 and 60 feet in diameter and the nozzles and pipe are 6".

I used the API 650 nozzle option in CAESER for my nozzle node but when I looked at 650 Appendix P it said that the practice was only recommended for tanks 120' in diameter and larger. Is there an alternative calculation that is more appropriate for my case?

If not, how valid is the calculation and can I take credit for the reinforcment pad thickness by adding it to my shell thickness? I did not notice any mention of using the reinforcement pad thickness in Appendix P but the example problem notes that the reinforcement for the nozzle is in the nozzle neck-- implying that you can take credit for it in general. This was doubly confusing given that it is a 24" nozzle and the begining of Appendix P says that nozzles should meet the requirements of Table 3-6, which calls for reinforcement pads on nozzles over 2".

Anyway, thanks for your help.

Kind Regards,
charles

Regarding your question <em>"I used the API 650 nozzle option in CAESER for my nozzle node but when I looked at 650 Appendix P it said that the practice was only recommended for tanks 120' in diameter and larger. Is there an alternative calculation that is more appropriate for my case?"</em>

No, there is no alternate API-650 computation method that I am aware of. Appendix P was developed from technical papers published which described the instrumentation, full scale testing, and FE verification of two tanks. That's it, two tanks. Both were large tanks, diameter about 120 ft, hence the code (limit) clarification.

One alternative would be to perform an FE analysis of your own to qualify the nozzle(s). <em>You may want to consider the FE/Pipe program from Paulin Research Group, I know this has an API-650 nozzle template.</em>

"Can you take credit for the reinforcing pad?" Yes, indicate to CAESAR II that the reinforcing is on the shell. This will use the figures labeled similarly from the code. According to the API references, these curves were developed from nozzles where a repad existed and its thickness was equal to the tank's shell thickness.

[ May 24, 2001: Message edited by: rich_ay ]

Another method is to use WRC297 which has been addressed in API650 App.P, have a look to that section , Hope you can get good result.

Regards

Shahram

I strongly suggest you stay away from the current WRC Implementation in APi-650 Appendix P. This section of the code is full of errors.