Diesel Leak rate through a buried pipe
Diesel Leak rate through a buried pipe
(OP)
I need to calculate the rate diesel would leak out of a 2" steel pipe buried 3' below grade. The hole was approx. 1/4" diameter and the pipe is under 20 psi pressure. I know the soil type will probably affect the rate. If it is easier, can I find the maximum leak rate assuming the pipe were not buried and then deal with how the pipe burial would affect the rate?
Thanks
Thanks





RE: Diesel Leak rate through a buried pipe
"Do not worry about your problems with mathematics, I assure you mine are far greater."
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RE: Diesel Leak rate through a buried pipe
Thanks
RE: Diesel Leak rate through a buried pipe
Also, the orientation of the hole may have an effect. Not sure how, but it may.
"Do not worry about your problems with mathematics, I assure you mine are far greater."
Albert Einstein
Have you read FAQ731-376 to make the best use of Eng-Tips Forums?
RE: Diesel Leak rate through a buried pipe
RE: Diesel Leak rate through a buried pipe
If you assume the soil conditions outside the pipe will further retard that, by let say 80% (pure guess here), then the total leakage rate is 0.3% of the original total flow rate.
That's my unqualified off the top of my head guess.
What was the other consultant's number?
"Do not worry about your problems with mathematics, I assure you mine are far greater."
Albert Einstein
Have you read FAQ731-376 to make the best use of Eng-Tips Forums?
RE: Diesel Leak rate through a buried pipe
Hopefully it will give you valid approach and better results.
See the below link for detail:
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RE: Diesel Leak rate through a buried pipe
RE: Diesel Leak rate through a buried pipe
Maybe like areas with a lot of clays?
"Do not worry about your problems with mathematics, I assure you mine are far greater."
Albert Einstein
Have you read FAQ731-376 to make the best use of Eng-Tips Forums?
RE: Diesel Leak rate through a buried pipe
Just figure your leak rate without the soil.
RE: Diesel Leak rate through a buried pipe
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: Diesel Leak rate through a buried pipe
Only reference I came up with in a little searching discusses other factors that influence leak rate besides the size of the hole-
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RE: Diesel Leak rate through a buried pipe
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: Diesel Leak rate through a buried pipe
RE: Diesel Leak rate through a buried pipe
RE: Diesel Leak rate through a buried pipe
The reference you found seems to suggest that well compacted backfill is used over pipelines, which in general is very far from the truth. While it may be true at specific constructions in city street works and rural highway undercrossings, I can assure you that it is absolutely not the case for the thousands of miles of oil pipelines making their cross-country runs as they try to avoid those areas where extra care in backfilling is demanded by public works and highway authorities.
RE: Diesel Leak rate through a buried pipe
I was going to re-emphisize that full pipeline pressure can be felt by soil near a hole. If one looks at the equation for flow across across a nozzle, valve or hole, approximated by, Q = Cv * (Pi^2 -Po^2),
Pi = pressure inside pipeline
Po = " outside
you can see that when the flow is very small, as it is when it is just starting to develop and leave the pipeline through a new hole, the pressure drop from inside to outside = apx. 0, so full pipeline pressure is there. When flow through the leak reaches sonic velocity, both flow and the pressure drop across the hole are at maximums and you have the conditions to determine maximum flowrate possible from the leak.
So, IMO its very difficult for soil to stop a pipeline leak. On one hand maximum acceleration pressure will push a grain out of the way; on the other, it must resist full momentum from a maximum flow velocity. Energy (pressure head or velocity head) cannot be created or destroyed by soil trying to resist a pipeline leak flow. The only way soil grains have to reduce the total energy head is by providing friction to the flow, which would require very high cohesion between individual grains.
<OK, now hit post button>
RE: Diesel Leak rate through a buried pipe
v= (2*dP / rho)^2
Q=A*v=9 gpm
In a short time of beginning of leakage, soil adhered to the pipe will be broken. It may be less than 1 second or so. Negligible. Once it happens, soil resistence will be zero and then only resistence will be the liquid back pressure formed by the diesel spilled. It will take long time and can't be higher than 3 ft head, so again not significant. Friction loss at the opening can be more significant, but not very big. My ball park guess is 10 to 50%.
RE: Diesel Leak rate through a buried pipe
RE: Diesel Leak rate through a buried pipe
192 bbls/day
Only some $14,000 a day if it was today's market crude oil. Price for diesel is on your local gas station pumps. Its a lot higher here I'm sure.
RE: Diesel Leak rate through a buried pipe
BigInch, your vena contracta factor 0.62 is more specific than my 10~50% friction loss.
One thing I reconsider is that resitence by liquid can be bigger than I originally thought. If ratio of compactness of the soil to leakage flow rate is high, it can be prettry significant, because liquid need to penetrate the soil.
RE: Diesel Leak rate through a buried pipe
Besides, whenever fluid is stopped in its path leading back to the hole, pipeline pressure catches up to it. Full pressure can be transmitted through the tinest hole provided that there is (effectively) no flow. Your equation predicts the same effect. What is pressure DROP when V = 0?
http://virtualpipeline.spaces.msn.com
RE: Diesel Leak rate through a buried pipe
RE: Diesel Leak rate through a buried pipe
Just remember the Donald Duck cartoon. The dam doesn't blow, until he puts his finger in the little hole.
http://virtualpipeline.spaces.msn.com