We have got XV on-off shutdown valve installed on natural gas pipeline. It is a Grove valve, with double acting cylinder: air to open and air to close. If we lose air and the valve is open, so the valve position is maintained open. The valve must be fail safe close as per SI 825/1996.

Is there any solution ?

 

Replace the cylinder with a single-acting spring return. When air fails cylinder closes.

 

You must use a spring return fail safe close valve
- Air to open, no air or air failure to close.

regards
Sekar

 

As the others have said use a spring return actuator, however if a double acting actuator must be used, provide a back up air cylinder to drive the valve closed in the event of an air supply failure.

 

Rog is correct, if you end up using a double acting actuator instead of a spring, you can have a back up cylinder.

If this is a shutdown valve in a serious application, you may want the additional back up cylinder to have enough volume for 3 strokes. This is to ensure that the valve will still have enough volume to close if an emergency situation occured while you were stroke testing it.
Some manufacturers also supply hand pumps, although they work very slow, it might be an idea. Make sure you get a hand pump that does not spring back into your face when you use it. I have known of people hurt themselves from these things

Hope this helps
Phil Hughes
EESIFLO

 

Even using an air cylinder will not solve the problem unless the solenoid is de-energized if the desired fail position is fail last

 

> Even using an air cylinder will not solve the problem unless the solenoid is
> de-energized if the desired fail position is fail last

I think that de-energizing the solenoid is not relevant here!?!
On loss of instrument air the mechanical spring return valve will fail closed (regardless if the solenoid of the directional control valve is energized or not).
The issue here is to provide pneumatically with the same spring return action on the double-acting cylinder valve.

By using an air-pilot operated 3port/2way valve connected to the "closed" line of the double-acting cylinder valve, you can redirect the back-up cylinder pressurized air to close the double-acting cylinder valve on loss of instrument air (instrument air to be used to pilot the 3/2 valve).
By providing a check valve at the inlet of the 3/2 valve you will lock the pressurized air in the "closed" chamber of the double-acting cylinder valve.

Important:
The air on the other chamber (the "open" chamber) of the double-acting cylinder valve is exhaust on loss of instrument air regardless if the solenoid of the directional control valve is energized or not.