Latched open check valve

[HaroldSnyder]

I am looking for a check valve that can be latched open to allow reverse flow when desired. This will be in LNG service, -250F, 24" Class 150. Any thoughts?

 

[pennpiper]

"LNG service, -250F,"
This sounds like cryogenic service, right? Lots of real thick insulation?

If it is possible I recommend a Bypass line with a Car sealed closed (Locked closed) line spec block valve. It could be smaller than the existing 24" line size.

prognosis: Lead or Lag

 

[LittleInch]

My immediate thought was don't do it. I nhave seen reversible or latched open swing check valves in the past, but only on low pressure normal temperature equipment. Even then the risk that the holding open mechanism with either leak, get jammed in either direction, mal operation (held open when it shouldn't be) or worse of all, fail in service is far toohigh to justify the relatively low cost of simply installing a normal isolation valve in a bypass loop. Any sort of check valve held open can then slam shut with normally destructive force which basically risks rupture of the valve or breaking the disc / flapper.

All for the sake of two tees, two elbows, two flanges and an isolation valve??

Normally if you're installing a check valve there's a good reason for it. To be capable of removing that safeguard, there has to be a very good reason or the check valve isn't needed in the first place...

My motto: Learn something new every day

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

 

[HaroldSnyder]

I agree the bypass is ideal. The problem is there is no room. We would have to re-route a bunch of piping to make room. I also have used a similar valve in the past (1978) but google doesn't find that one.

 

[BigInch]

Cameron has bought out Tom Wheatley. They are the best piggable swing checks you can buy. To API 6D spec. Lever is for holding open (temporarily - as the cut sheet explains) when reverse pigging, or whatever, normally only during construction, or if some operating problem develops. I have used them up to ANSI#1500, but not with LNG. See if they offer that service.

http://www.c-a-m.com/forms/Product.aspx?prodID=6f85297c-23c0-479a-9389-c3fd38bebd34

Learn from the mistakes of others. You don't have time to make them all yourself.

 

[dcasto]

In the old days they were called checkeroo valves. I don't know what happened to them.