Over pressure in piping

[RFZC]

A volume of liquid trapped in an enclosed piping system has the potential to expand with a corresponding rise in ambient temperature, How can I relieve that over pressure in LPG and gasoline pipings? Is a relieve valve the better solution?

 

[imok2]

How about an expansion tank with a pressurized bladder

 

[bvi]

You will need a liguid thermal expansion relief valve, routed to a safe location. That's the normal provision.

 

[Sharik]

In Canada, little, liquid thermal relieve valves are mandatory on LPG piping between each pair of isolation points (block valves, positive displacement pumps, check valves, etc.). If this is an outdoor installation, piping the thermal relieve valves to a safe location is not required (usually these thermal relief valves are little, 1/4" units).

For liquids which do not vaporize when the pressure is reduced out the thermal relief valves (gasoline, kerosene, etc.), the design of the thermal relieve valves is more of a traditional safety valve and these are piped to a safe location.

All blocked in sections of piping which contain an expansible fluid, must be protected against overpressure.

 

[pablo02]

Liquid petroleum products have the same problem -- went to work at a plant where provisions for overpressure of #6 fuel oil (bunker C) were not accounted for: oil seeped out of every packing, flange, pump shaft, everywhere -- the operators tried closing and wrencing down every valve to reduce the problem, couldn't figure out why it got worse, until I explained to them what the problem really was:

anyway, our systems are usually designed so that a) every positive displacement pump had either an internal relief, or, depending upon the use and location, a relief back to the supply, etc. (supply usually open to tank); b) every section of pipe that could be physically isolated usually had a relief valve around the isolation valve or a relief back to the tank, etc; and c) we established valving procedures (which valves were open, which valves were closed) under all conceived operating conditions to account for thermal expansion

for our fuel oil, relief to atmoshere (to the ground) was not an option -- I would assume that in the USA, consideration for fugitive emissions might have some bearing on how relief valves are piped (but, I plead ignorance here)...