Underground Pipe Leak Detection

I would check the original plans for design life and materials used, and make sure they match....then if there has been any extraordinary events that may have effected the pipes....What has sparked this concern? Was there an incident or what? If the pipe is within the design life and no other known incidents have occurred to effect them, then I would inspect the pipes at various locations, and possibly do some testing, if that seems warranted....

http://www.astm.org/Standards/E213.htm

<...What has sparked this concern?...>

In a pipe carrying flammable materials?

Dear SolarEagle,

Thanks for the respond. I should put forward the questions to the car manufacturer. In the mean time would like to understand the testing that you attached. This does not sound like conventional UT, nevertheless, doesn't the sound wave gets distracted due to the fact that the pipes are buried?

Any conventional UT will have to be performed on the un coated surface of the actual pipe. A typical T gage operates between 2.25 to 5 Mhz and is normally a dual element. You cannot read thru dirt.

If its that critical the only method is a PIG.

I presume that the pipes are metalic construction (Since they've asked a welder for advice) and of significant bore.

I'd suggest they investigate "electromagnetic pipe condition monitoring" or similar, where a sensor is sent through the pipe and using eddy current and such get a continuous image of the pipe that will enable determination of effective remaining pipe wall thickness and such.

This is a very specialist field (read very expensive contractors) and has limitations in resolution of faults, especially where there are other fittings on the line.

The sensors are usually "tethered" so that they can be recovered, but also to give accurate position detail of observations.

We investigated similar for water mains, but it's almost cheaper to renew than to run the contract each 10 years. (But obviously the risks with a water leak are VERY different to fuel or LNG.)

n the petroleum industry they do this all the time with a "pig", a small machine that travels the length of the pipe accumulating various data. so you are far from the first that wanted to inspect the interior of a pipe!

Dear Fredski,

Thanks for the respond. I have heard about this pigging method. Unfortunately these pipes doesn't have the facilities to do pigging.

A "small" correction, here... but, more often than not the technology employed for pipeline pigging (obviously, if buried, you don't want to have to excavate the whole line to inspect it) is Remote Field testing.

"Plain" eddy current has its places, just as every OTHER Method of nondestructive testing. They each have their own innate capabilities and limitations.

I await more details / specs on this piping system. Looking ahead (Post 11), I see that the 'right-track' is now engaged.

Given that these buried pipes carry "gas, oil, or other hazardous liquids", they fall under different Code than water lines. I would certainly TRUST that they are being cathodically protected, as per NACE Standard Recommended Practice RP0169 ("Control of External Corrosion on Underground or Submerged Metallic Piping Systems").

"Grab a copy" at the NACE website. "Good stuff." And best wishes for a successful interrogation!

"PS" ... Certain agencies of the federal government get "itchy" when they discover such systems to be "INC" (an Incident of NonCompliance, or In Non-Compliance).

Fines can be outrageous (like, $50k per day, so long as the situation REMAINS in noncompliance).

Our Code of Federal Regulations is online and searchable (there is NO EXCUSE for "Ignorance of the law"... ("no-one is excused").

Do a "Search" in Title 49 (which covers "Transportation", including transport via pipelines of hazardous gas/liquids) searching for references to NACE.

Lotsa people (even many who work in the industry!) do NOT realize the relationship, so-to-speak... When a "Standard" or a "Recommended Practice" is referred-to within our Codes, IT *becomes* ("By Reference") LAW.

Best wishes.....

"PPS" ... for those not "Search_Savvy" ... click the pic below to link-to (Search):

Once again, the search for NACE will bring-up literally scads of results ... including:

Do everyone a favor. Suggest that you are not the correct entity for this inspection job and refer them to a local vendor who will know how to help them, without guessing about test methods and equipment required.

You will gain two friends this way. The car manufacturer, and the testing organization that you recommend for this task.

That is the only correct response, anything else leaves you culpable, is unethical, and misleading to the client. GA

Dear Lyn,

I agree that I am not the right person for the job. I am just giving the car manufacturer the possible options that he can work with. I am also seeking advice from local NDT companies for possible inspection methods. At the same time would like to advice him who could do the work. Definitely not me. Thanks for the advice. Appreciate it.

I have heard about cam mounted on machine which goes inside water pipe line and examines the condition of the water pipe line. This machine is used by Mumbai Municipal Corporation at Mumbai, India. I do not know if this will machine will be suitable for petrol or LNG.

Ground Penetrating Radar (GPR) utilizing a 3D Modeling Software will provide you with a reasonable enough image of buried piping in order to identify damage or corrosion zones, there are several technologies available that a GPR provider should be able to advise you on. I would consult with CH2M Hill on this, they are pretty Savvy consultants and up on new technologies.

Hmmm... not to argue, per se, but, having taken a short course (with pretty good 'hands-on' stuff) in GPR technologies, I would be reluctant to suggest it as a first manner of approach.

Even here, one can assimilate that the information divulged would be 'second-best' to other nondestructive evaluation methods.

GPR *is* great for tracing-out the layout of a pipleine and displaying other utilities, etc that cross it along its path. Unfortunately, corrosion in pipelines is frequently exacerbated at the "6-o'clock" (bottom) of the line, and GPR won't "see" anything but the top-half at best.

Everyone WANTS ... "A magic bullet" for their need(s). So far, nobody has invented one.

(PS) Also see THIS...

For any GPR and Underground Scan questions you should checkout US Utility Potholing they have tons of information on this subject and offer this line of work for good cost.