Need some ideas if anyone has expertise with diesel fuel systems:
I have three outdoor above ground bulk storage tanks for No. 2 diesel fuel. Each has a pump discharging into a common supply line.  A  check valve at each pump prevents backflow if one of the pumps fails.  The system is idle most of the time.
When the weather gets hot, the pipes heat up and the fuel expands, causing leaks at mechanical joints.  There is no relief valve in the system currently.
I'm concerned that if I put in a relief valve, at some point it won't reseat, then I'll have an open path back to one of the tanks, causing it to overfill if its pump fails.

The pump manufacturer's literature recommends a "pressure relieving check valve".  I have not been able to find one on the market, and the manufacturer does not have a source.

Would it be better to put a backpressure regulator on a return line?  Is there a standard design for a fuel system like this?  Obviously I don't want to spend lots of $$.

TRVs (thermal relief valves) are typically used to control the pressure thermal pressure rise.

Do the TRVs need to be listed per ASME BPV?

If I recall, B31.3 does require listed valves, B31.4 does not.  I have used Swagelok R3A valves for B31.4 designs inside containment area and Anderson Greenwood 81P when a listed valve is required or if valve is located outside of containment area.

I can't see how any relief valve operating on seperate tanks can prevent one stuck valve from causing its tank to overfill.  Can you plumb the tanks to have a common outlet manifold (so that they will all seek the same level)?  This could be independent of the pump manifold, if necessary, but would just need to be sized to allow worst-case backflow (through stuck check/relief valve) to slosh into the other tanks under worst-case minimum gravity head difference.

If you have a positive head on the pump suctions, why not run a small diameter pipe with an orifice back to the suction side of the pump(s) or tank(s).  The orifice diameter should be minimized and could act as a stuck open thermal relief valve.  However, flow thru the device will be negligible during pump operation.

MORE NEWS