2 replies to this topic

[process705]

Hi Every one:
I have a a few questions regarding thermal PSV. I hope you guys can answer me.
(1) Can One do fire case calculation PSV located on pipe?
if yes how would you justify that or Not still how would you justify?
(2) In what conditions thermal case PSV can pop open?
is there any other source for heat beside sunlight. ( if One's pipings are in process building.)
I really appreciate for the answer in advance.
Thank allot.

[ankur2061]

process705,

Thermal PSVs and Fire case PSVs are entirely different. Fire case PSVs generally have very high capacities whereas thermal PSVs are small and have very low capacities.

If your pipe falls in the fire zone and has sufficient inventory then you may provide a fire case PSV.

Thermal PSVs operate only due to expansion of the blocked-in liquid contents due to temperature rise of the pipe contents. These are provided to prevent thermal expansion of liquid by solar radiation. It is important to note that thermal PSVs also known as Thermal expansion relief valves (TERVs) are only provided in 100% liquid filled lines. If the pipe contents are not 100% liquid phase then TERVs are not required.

Finally, if there is an external fire and the liquid contents get heated up the thermal PSV or TERV will also pop if the pressure in the pipe segment where the TERV is located exceeds the set pressure of the TERV. However, they will prove totally inadequate to relieve the rapid high pressure build-up in the pipe segment in case of a fire because of their insignificant relieving capacity.

Hope this helps.

Regards,
Ankur.

[fallah]

If your pipe falls in the fire zone and has sufficient inventory then you may provide a fire case PSV.

Normally for the pipe falls in the fire zone,PSV for fire case has not been considered.Pipe inventory in fire case would be included (as associated piping) in calculating the relevant vessel/drum/... volume leading to PSV relief load determination.