Redundant SOVs

[ali.abbas]

Hey Guys,

Does anyone here have any experience with using SOVs in a redundant configuration?

We are planning to install a shutdown valve at our site on the main gas line. The criticality of the line is such that the shutdown valve MUST NOT close inadvertently since that would mean a definite site shutdown. Therefore we intend to eliminate all single points of failure. SOV is one of the vital component, failure of which will directly result in valve closure and therefore Ive been thinking on lines of installing SOVs in a redundant configuration, like a 2-out-of-2 or 2-out-of-3 configuration. However, I haven't seen a practical implementation and therefore would appreciate if anyone can share their experience or knowledge in this regards.

Regards,
Ali Abbas

[ali.abbas]

Hi Guys,

I am pasting ing a link to an article on implementation and use of redundant SOV's underneath. Gives a very good concept of how SOV's may be installed in redundant configuration.

http://www.norgren.com/document_resourc ... orgren.pdf

Any further comments/information on the subject are most welcome.

Regards,
Ali Abbas

[AbsarShah]

Ali, having redundant SOVs on the same shutdown valve will not enhance the safety factor of the valve in any way. Even the idea of eliminating the 'single point of failure' is a little abstract. Your SOVs on a shutdown line will be Fail-Close, and so will the SDVs, so by adding another SOV, you're actually adding another point of failure rather than removing it. Besides, SOVs are inherently very reliable devices, so a redundant solenoid just for this purpose wouldn't make sense.

If the objective here is to prevent spurious trips, then credit for the safety factor can be taken in one of two ways: A - adding a redundant Shutdown valve in parallel, or B - providing partial stroke testing on the single valve.

[ali.abbas]

Absar,

Check out the following link. This product seems to be the answer to our question. Its got redundancy as well as Partial Stroke Testing.

http://www.ascovalve.com/Applications/N ... ntrol.aspx

I also have a presentation I got from our local suppliers of Asco which gives a good insight to the product. Unfortunately, its size will not allow me to upload it on this forum. If you wanna have a look, I'll email it to you.