Double valve operation in cryogenic service

[LSUUR]

Hello All

I would like to get advice on problem I am facing.

I have delivered few small packages as attached file, two vessles are there and one is operating, one is stand by.
Fluid is LNG with oil particle.(Operating temp : -146 degC)
When change from operating to stand by(verse is same), we open/close double ball valves(5 inch).
(1 time per month, valves will be opened or closed)

Problem is many claim comes out from customer about valve(seat) leakage, Customer is saying valve quality problem,
Valve company do not agree with quality, they are in doubt for using double valves for LNG application.

Can you advise if double valves shall not be used for LNG application? If so, is there any other options we take?(double valves are in project specification)

 

[LittleInch]

Nothing attached.

What pressure drop?

What is valve spec?

What is LNG with oil??

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[gerhardl]

As LittleInch say: no details, no precise answer, but yes! Any valve application giving repeated problem is either a wrongly selected valve solution, or an unsuited valve because of piping layout or flow and/media/operational conditions.

Advice: contact one of the worlds leading LNG valve producers, give all details, and ask for an offer. In this case 'leading' means a company with at least 50 years experienc and wide range of top-rated different types of LNG valves.

Oil and LNG could cause problems if the valve is not especially suited or built for this. Get one with long term references for this particular conditions,

 

[LittleInch]

LNG is normally -168C. So this "oil" must be quite interesting.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[mk3223]

Per my understanding, the double valves is used quite typical in the LNG design.
Instead of "who said what", may replace one of the "leaking" valve in the field and take it to the shop and inspect for the root cause.

 

[itsmoked]

What about the pressure of heating up liquid>gas in the space between two valves?

Keith Cress
kcress -

http://www.flaminsystems.com