Expansion Joints Vs. Expansion loops 1

[rruipere1]

Hello tippers,

I have some kind of dilemma: when to use Expansion Joints or loops for cryogenic service, specifically LNG. I have gotten to the conclusion that expansion joints are cheaper, but if you have space you shold go for loops, that are better. Let me know about your thoughts. Thanks

 

[iainuts]

Hi rruip,
There have been a few discussions about this over on the pipe and fluid mechanics forum. Almost identical question here:

http://www.eng-tips.com/viewthread.cfm?qid=191334

The concensus is to use loops since expansions joints are prone to failure. I'd agree. For uninsulated or just foam insulated piping, the expansion loop is the best way to go.

The only time I've used something other than a loop is for pump suction lines which might be flexible metal hose, with or without braid reinforcement.

There is an issue however with vacuum jacketed piping and pressure vessels. Often times there is limited room inside the jacket for loops. Most VJ piping manufacturers use expansion joints throughout the piping. They can be either on the outer or inner line, there isn't a real standard for this. I've seen both.

Another location for expansion joints is on large diameter lines on tanks with relatively small annular space between the inner and outer vessels. In these situations, an expansion joint is often used, though it is not preferred.

 

[rruipere1]

Thank you very much. I agree with you totally.

 

[LSThill]

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L S THILL