Thanks guys for your help and comments. As I said, I do not plan to extrapolate API 650 to this application. We will use RISA to calculate the nozzle and roof stiffnesses.

These tanks are cone-roof with external rafters. As you suspected, I had a tough time trying to strongarm the CII nozzle flexibility engines (e.g. WRC 297) to fit this model. I have been around the horn with the client and the process folks and they are unyielding (how's that for a pipe stress play-on-words ;^) ). They do not plan to operate these valves except on plant-wide shutdown. We all know how that goes, however... All I can do is make my case and then try to make it work. I'll let you know what we come up with on the stiffnesses.

Thanks again for your help.
Pete Chandler

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Thanks,
Pete
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Thought for the day:
Good judgment comes from experience;
Experience comes from bad judgment.