4 replies to this topic

[zulu]

Hi All,

i am just going through one P&ID and i can see restriction orifice downstream of isolation valve( ball valve) . it is a pressurizing line so i guess the purpose is during pressurizing, the ball valve will be fully opened and RO downstream will restrict the flow according to its bore size. am i correct?? what if this RO is upstream of isolation valve???

thanks in advance..

[fallah]

Hi All,

i am just going through one P&ID and i can see restriction orifice downstream of isolation valve( ball valve) . it is a pressurizing line so i guess the purpose is during pressurizing, the ball valve will be fully opened and RO downstream will restrict the flow according to its bore size. am i correct?? what if this RO is upstream of isolation valve???

thanks in advance..

Without having adequate information about the relevant process and fluid couldn't be able to submit considerable assistance.

Anyway,if isolation valve and RO is located before a vessel (in the by pass line of main valve) seems you are right and they would be there for pressurizing.

I think the RO should be located downstream of the valve,unless the valve would be provided with hard trim against high fluid velocity.

[zulu]

Hi All,

i am just going through one P&ID and i can see restriction orifice downstream of isolation valve( ball valve) . it is a pressurizing line so i guess the purpose is during pressurizing, the ball valve will be fully opened and RO downstream will restrict the flow according to its bore size. am i correct?? what if this RO is upstream of isolation valve???

thanks in advance..

Without having adequate information about the relevant process and fluid couldn't be able to submit considerable assistance.

Anyway,if isolation valve and RO is located before a vessel (in the by pass line of main valve) seems you are right and they would be there for pressurizing.

I think the RO should be located downstream of the valve,unless the valve would be provided with hard trim against high fluid velocity.

yes, isolation valve and RO located upstream of pressure vessel and its a by-pass line( hydrocarbon gas) of the main shutdown valve.

what if RO is at upstream of isolation valve?? will it effect during pressurization as RO will give a constant minimum flow .

[Chem01]

Joule thompson effect, restriction orifices are located at d/s of valve to avoid cold temp effect to the valve. Two undesirous effects are the result:

-Low temperature then requires a valve with different specs and more expensive to cover a broad range of temperature
-condensation on the valve give rise to extra problems of stuck up, related to stem.

Even valve at u/s is provided at a specified distance from restriction RO.
Regards,

[pawan]

RO upstream of valve will not work as pressure at upstream & downstream may get equalize depending on valve opening. So RO should have isolation at upstream only to avoid any operational error.