Pilot Remote Sensors - special valving

[Bill3752]

We are installing a pilot to protect two steam flash tanks with same MAWP, etc. Due to inlet dP issues, we will be running sensor lines from the pilot back to the tanks. What special check valves, etc. are needed to make this operate correctly?

 

[don1980]

You shouldn't install a check valve in the remote sensing line. Normally all that's done is to install a 2-way valve at the vessel nozzle so the relief valve can be removed for maintenance.

BTW, pilot operated PSVs arn't often used in steam services because of the temperature. These valves have a lot of elastomeric o-rings which limit the max temperature. Some manufacturers can provide a small heat exchanger on the sensing line. That may or may not be suitable for this case - check with the supplier.