4 replies to this topic

[AENG555]

Hello,
For the discharge piping from a boiler feed water pump (typically at 1100psi and 145 deg.C), would a pressure relief valve be specified or will thermal relief be more applicable for protection against overpressure?
regards,
AENG555.

[fallah]

Hello,
For the discharge piping from a boiler feed water pump (typically at 1100psi and 145 deg.C), would a pressure relief valve be specified or will thermal relief be more applicable for protection against overpressure?
regards,
AENG555.

AENG555,

There is no difference between TRV and PRV in function point of view. Anyway, if you mean you may have overpressure due to blocked outlet on pump discharge line (pump in shut off condition) a PRV would perform the duty.

Fallah

[AENG555]

Fallah,
Thank you sir. I appreciate the advice.
Best regards.
AENG555.

[kkala]

What case is covered by mentioned PSV? Case of shutoff pressure higher than design pressure is covered by fallah.
Another case can represent a heater placed between boiler feed water (BFW) pump and drum. Valves at BFW in & out can be inadvertently closed, while heating medium still passes through the exchanger. In this case a thermal relief valve (TRV) has to be installed on BFW side, to protect exchanger from overpressure due to BFW expansion as its temperature rises.
Mentioned TRV is often installed on the BFW line between the two isolation valves of the exchanger (e.g. upstream of valve at exchanger outlet).
TRV or PRV is just terminology, both are PRVs.

[ankur2061]

AENG555,

Thermal expansion relief valves abbreviated as TRVs or TERVs are used for thermal expansion of liquid due to continuous heat input while the liquid is trapped and not flowing in a system (piping / vessel) between isolation valves on the system.

One of the prerequisites for liquid thermal expansion is that the system is more than 95% liquid filled. TRVs are most commonly found on the cooling water return side of heat exchangers (coolers / condensers) between isolation valves and in piping sections that can be isolated by isolation valves and can have liquid trapped in the isolated section and could be exposed to a heat input, for example heat input due to solar radiation.

Hope this helps.

Regards,
Ankur.