Design pressure and temperature and operating pressure and temperature

[Indy]

Hello,
I have a question regarding the design vs operating pressure and temperature in relation to temperature instrumentation (thermowell)on process piping. For example say we have a pipe where the max operating pressure is 7.3 barg and the max operating temperature is around 43 deg C but the design pressure is 16 barg and the design temperature is 60 deg C.
When it comes to the wake frequency calculations I would say that the design conditions should be used as these are the maximum values that the thermowell could see.
Is this normally the case or are the operating max pressure and temperature used?

Thank you

 

[TiCl4]

I would do both. I have not used these calcs myself in the past - is it possible that the resonant frequency might be hit with a lower density gas (i.e. at your standard op conditions) rather than at design conditions? I think the answer to that question is likely “it depends on XXX”, and personally would not feel comfortable only analyzing the design conditions if such a possibility exists.

 

[LittleInch]

From memory of wake calculations they can be a little sensitive to different paramters so the max pressure isn't always the worse case. It's the velocity and density which gives them the issue and sometimes this is higher at lower pressures.

I think you give them a few cases to run including max flow with min and max pressure, min flow with min and max pressure and a "normal" case.

See what the attached says

http://www.controlandinstrumentation.com/temperature/thermowell-wake-frequency.html

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.