1 reply to this topic

[mfelton]

What velocity do process engineers typically use when populating thermowell datasheets?

 

In this particular example the thermowell is installed in a section of pipe for which the design capacity is 20 MMSCFD. The system will operate at a maximum of 20 MMSCFD during normal operation. However, the flow rate through the system is modulated by an upstream choke valve. If the choke valve is opened fully inadvertently the flow rate could increase to 30 MMSCFD. This is outside of the design envelope and forms the basis for the downstream PSVs/relief system. In the event this occurs the system will shut down on PAHH and failing that the flow rate will be relieved through the PSVs. In this case the flow rate across the thermowell will be 30 MMSCFD until the system is shutdown.

 

In the past I would have specify the thermowell based on the velocity based on 20 MMSCFD as I consider it excessive to design for the flow rate associated with the infrequent relief situation.

 

Anyone agree and have any basis for this?

 

Thanks

 

Marcus  

[Pilesar]

I would provide velocity for both scenarios on the datasheet. The thermowell designer will need to avoid resonating vibrations and relies on the information you supply.