7 replies to this topic

[Mathi]

I am working in a brownfield project. I came across the following arrange of RO after the SDV. I am not sure of its purpose but it was mentioned that the RO was sized for gas blow by case.

 

Since the SDV is after the level control valve, when low low level is reached the control valve is going to close any way. Therefore, there is no need to consider gas blow by case at all.

 

If anyone has any other ideas, please share.

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[fallah]

 

Since the SDV is after the level control valve, when low low level is reached the control valve is going to close any way. Therefore, there is no need to consider gas blow by case at all.

 

If anyone has any other ideas, please share.

 

Mathi,

 

There might be the possibility of LV open stuck or its relevant control loop malfunction leading to wide open position; then if the gas blow by case following to LV wide open is credible, putting RO at LV downstream can be a preventive facility...
 

[Mathi]

Fallah

 

I am sorry. I failed to mention that the control valve is designed for Fail to Close (FC) condition.

 

So I don't think, we can consider the struck open condition but I am not sure whether a valve designed for Fail to Close case can reach struck open condition.

[fallah]

 

So I don't think, we can consider the struck open condition but I am not sure whether a valve designed for Fail to Close case can reach struck open condition.

 

Mathi,

 

Yes, it can reach stuck open condition or to be wide open due to relevant control loop malfunction; even if is being designed for FC condition...

[Mathi]

Fallah

 

Okay. Thank you for very much for your responses. 

[breizh]

Mathi ,

What about the position of the shut down valve in case of lack of energy ( Air or power supply) ?

Just curious.

Breizh

[fallah]

Breizh,

 

A SDV or ESDV is to be designed in FC position....

[Mathi]

Breizh

 

As Fallah said, the SDV is designed to Fail to Close.