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A short straight piping with a cap is a dead leg?

A short straight piping with a cap is a dead leg?

A short straight piping with a cap is a dead leg?

(OP)
The distance between the cap and the branch pipe is about 700mm. So the straight pipe between the cap and the branch pipe is a dead leg? Thanks a lot.

RE: A short straight piping with a cap is a dead leg?

What fluid? For some services you definitely don't want this.

If the line is extended for support purposes why not use a dummy leg.

 

RE: A short straight piping with a cap is a dead leg?

(OP)
The fluid is n-butane and air. It seems that the fluid can't be corrosive to the piping.

RE: A short straight piping with a cap is a dead leg?

Not a good idea as air seems to always come with some water content, which eventually drops out and collects in places like dead ends.  Air (N2+O2+H2O, there's that O again) usually leads to some amount of corrosion.  No better place for that to occur then in a dead end where any deposited water tends to stick around.  

http://virtualpipeline.spaces.msn.com

"What gets us into trouble is not what we don't know, its what we know for sure" - Mark Twain

RE: A short straight piping with a cap is a dead leg?

In addition to the above, I'd consider the diameter of the pipe: If you have a 2" pipe and a 24" deadleg - that's bad. If you have a 24" pipe with a 24" deadleg that might not be as bad. Also - what is the orientation of the deadleg - up, down, or horizontal? And is the deadleg off the run or branch of a tee?

I would think that the worst case would be a 2" pipe with the flow coming vertically down to a tee with the deadleg on the run (i.e. down) and the flow going horizontal. You'd get a cyclonic type separation of any water which would accumulate. Best case would be either a 24" with the opposite flow: Vertical up with the deadleg on top, flow turning horizontal - or maybe a horizontal run with the deadleg on the branch of the tee going up (not likely to ever see liquid).

jt

RE: A short straight piping with a cap is a dead leg?

Depending on the fluid, and if the leg is vertical, it could also be to control the "water hammer" effect when a valve is closed.   

Mike McCann
MMC Engineering

RE: A short straight piping with a cap is a dead leg?

(OP)
I am sorry for not saying the orientation of the deadleg. The deadleg is horizontal. And the fluid is tranferred at 145 degree centigrade and 1.3Mpa. So it may mean that there is only steam in the pipe and the fluid may not be corrosive to the pipe?

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