5 replies to this topic

[tore.alvestad]

Hi

Is a fire relief valve needed?

We have a two vertical barrel pump in parallel. One operating and one standby. The pump barrel is above grade. The choice of a vertical pump has to do with the seal arrangement not the NPSH. Please see below for details.

Dimensions barrel
Height: 1.0 m
Diameter: 0.7 m

Fluid (mol):
Methane: 35 %
Ethane: 53 %
Propane: 6 %
CO2: 6 %

Temperature: -60 degC
Suction P: 25 barg
Discharge P: 51 barg


We have till now regarded the can as a piece of piping and therefore not provided a fire relief valve. There is though a valve for thermal expansion.

Any suggestions are appreciated!

Regards,
Tore

[pleckner]

I'm not sure what a barrel pump is but if this is a pressure vessel, then per ASMEyou need a PSV, it is too big to meet the exclusion criteria. If external fire is a credible scenario, then the answer is yes. If this material was able to pool and there was a source of ignition, then fire would be a cerdible scenario.

[tore.alvestad]

Thanks for that Phil.

It is true that it is pressure vessel, but ASME VIII states in U-1©(2):

"Based on the Committee's consideration, the following classes of vessels are not included in the scope of this Division; however, any pressure vesses which meets all the applicable requirements of this Division may be stamped with the Code U Symbol:
(a) those within the scope of other Sections;
( fired process tubular heaters;
(c ) pressure containers which are integral parts or components of rotating or reciprocating mechanical devices,
such as pumps, compressors, turbines, generators, engines, and hydraulic or pneumatic cylinders where
primary design considerations and/or stresses are derived from the functional requirements of the device;"

I believe that this particulare equipement is in the grey zone and it would therfore be interesting to know what is beeing practised.

What exclusion criteria are you refering to?

Regards,

Tore

[pleckner]

The exclusion I was referring to had to do with size, less than 6" in width would allow you to exclude the vessel from the scope.

As I said, I'm not familiar with a barrel pump so I can't comment on reality. If the "can" is indeed a part of the pump, then it can be excluded from the requirements of the scope. If it has a U stamp, then you already answered the question, you must include the requirements of the scope and install a PSV.

To be considered pipe or a vessel can indeed be tricky. But remember, any vessel can be fabricated from pipe but this does not make the vessel a pipe.

In general, we try to stay within the spirit of the code if not by the letter. If the item is used as a vessel, then it should be considered one. You have to be able to sleep at night knowing that you have not created a potentially life threatening situation for someone operating and or servicing the equipment. Trying to skirt the spirit of the code is not my idea of safe practices.

[tore.alvestad]

Thanks again Phil

Looks like we are going to protect the pump barrel by providing a vent line back to the suction drum. The vent line will be sized for fire relief load. The PRVs on the suction drum are a bit big for the service, but the client prefers this to implementing new relief valves.

Regards,

Tore

[proinwv]

In the US fuel storage vessels generally require emergency venting for fire exposure. Offhand I am not sure that such a small vessel would be covered.