isolation valve on refinery flare header

[MP2012]

Hello Everyone,

We have a alternate flare header with flare for in Refinery which is isolated with knife gate valve, is it correct type of valve for isolating flare? Appreciate your input, comments and suggestions.

 

[don1980]

In my experience, knife gates are used when there's a possibility of debris in the valve seat. Someone may have had that problem in the past. If that valve is working for you, then I'd keep using it.

 

[MP2012]

It didn't work at one point. What could be the alternate? The flare line is coming from flare Knock out drum, so I belive there should not be any possibility of debris.

 

[LittleInch]

What is this valve isolating - the flare from the header or some sort of crossover valve between one header and another?? when you say it didn't work what do you mean - it didn't close or it didn't seal??

Valves on flare headers themselves are relatively rare, normally the last thing you want to do is to accidentally isolate your flare, but maybe I've misunderstood what it's use is. A sketch of the system or a much better description could generate some ideas, but vague questions with no details don't normally get a lot of responses....



My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[MP2012]

The valve is isolating flare header from alternate flare. It didn't close.

 

[LittleInch]

I assume you mean it didn't seal / close completely, but from a cursory look at knife gate valves, a flare header service does not look to be it's ideal use (slurry, viscous fluids, water) as even d/s of a knock out pit, you will get hard debris blocking the valve and sitting in the seat crevice which the knife part can't crush / cut through.

Looks to me like you need something more like a high performance butterfly valve or two or a through conduit gate valve which rises to close. For really good sealing try a double expanding gate valve or plug valve which shields the seals from normal flow and only epands them onto the sealing face when required.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[maddocks]

We've gone to full port CSO ball valves for minimum restriction. However, a knife gate should also be ok as long as it's mounted sideways to keep the junk away from the seat.