Thermal prv relieving directly back into petroleum tanks

[caluna]

At our tank farms we have prv's to relieve towards the tank. The ones closest to the tank, (across the gate valve at tank outlet) are on a bypass line which goes around the gate valve, but both ends of bypass connect to the outlet pipe (ie, one does not go directly into tank) . Any reason we cannot have that prv relieve directly into the tank, provided the tank connection meets API? We used to have a standard detail of this set-up but for some reason we do not use it any more.
Thanks

 

[dcasto]

you can do it if you want. The question would be why? A 1/2" line around a block valve is smaller and more cost effective than extending the PSV outlet all the way bac to the tank. I would even use a psv, i'd use a 1/2" adjustable check valve.

 

[caluna]

Good point! I guess we don't have to. We use a 1 inch line but still easier than doing the connection at tank.