liquid in pipeline (posted in PFM)

[picasa]

This question was previously posted in BPV forum. I am trying this forum too. Sorry for the repeated post.

How do you detect if a decomissioned pipeline has any liquid in it (remnant). You dont want to cut into the line. You got to use some kind of measurement technique to detect any liquid in the pipe if possible. Any ideas?

 

[pmover]

is pipeline above/below grade? how long is pipeline? perhaps finding/exposing a lowpoint and firmly tap the pipe. any liquid will "dull" the ring (sound).

good luck!
-pmover

 

[StephenA]

What sort of liquid?

Can you pig the line?

Send a camera down the line?

If hydrocarbon, blow air through and detect fumes?

How desperate are you? Suck a vacuum and see what boils off.

Some more information on what you are trying to achieve would help.

 

[Latexman]

Pour HOT water over a horizontal, low lying section. If there is a liquid/vapor interface in the pipe, the metal on top in the vapor space will be noticably hotter than metal on the bottom in the liquid space.

Good luck,
Latexman

 

[unclesyd]

I would use either a radiograph, corrosion or cord shot or a backscatter gauge to ascertain if there was anything in the pipe.

 

[Ashereng]

picasa,

Is decomissioned the same as abandoned?

Why do you want to know if there is any liquid inside the line if it is abandoned?


StephenA,

The short answer is no. I am currently dealing with abandoned crude transmission lines. If I open it up, I am responsible for environmental remediation. So, no. I can't open it up to put a camera down. I definitely can't pig it because I will need to cut into it to tie a pig launcher/receiver. I also can't blow or pull from it.

I am taking all precautions to make sure I don't disturb it in any way, including using a casing for my HDD so I won't hit it should something go awry.


Latexman,

Your solution may work if the liquid volume is appreciable. If there is trace liquid on the bottom, the difference in temperature may be too close to notice, even with an IR temperature gun?

"Do not worry about your problems with mathematics, I assure you mine are far greater."
Albert Einstein
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[MortenA]

Wouldnt an empty pipeline sound different that a full if you banged it with something? (A specialists company such as some leak detection companies that uses sound to locate/detect a leak may put it in more technical terms )

Best regards

Morten

 

[zdas04]

I think this thread is a testiment to the silliness of putting a pressure-containing seal on piping that is abandonded. Many jurisdictions require abandonded piping to be capped with pressure-containing seals, and many companies do it even when they don't have to.

My fear has always been that the line was unpiggable (either through lack of facilities or accumulation of scale) and had a non-trivial amount of liquid hydrocarbons that had condensed out of the flow. In this case it is difficult to predict the equilibrium temperature of any section of the pipe (since without flow convection currents will change temperature fairly slowly) so it is impossible to predict the pressure that may build up. A line filed to 1-2 psi with volitile vapors could easily kill a construction crew that hit it with a track hoe.

There is no technique that would be effective in a line of pipeline dimensions (i.e., hundreds of feet to multiple miles) since you would have to dig up the entire line to find all of the potential liquid traps. The best technique is to grind and punch the line and sample (or flare) the vapors. When I go to that point, my preference (if the local regulations allow) is to convert the punched hole to a pipeline-diameter hole, cover it with tape (the weaker the better), and backfill the hole.

The debate over acceptable techniques to abandon a pipeline has raged hotly for decades. Some people want the line filled with concrete, some want a nitrogen blanket, some just want end caps (this is the most common), and some prefer to leave the ends open (either with tape or nothing) and let natural processes return the steel to the soil over eons. Having done all but the first and having to deal with the potential of unmapped pressurized lines, my preference is to cut off all fabrications below grade and put tape over the ends to keep burrowing animals from using it for a den and being done.

Since your line is pressure-sealed, I'd do the grind-and punch technique.


David Simpson, PE
MuleShoe Engineering

http://www.muleshoe-eng.com

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