Leak Detetion

A method that can be used is aerial photography in the infrared band. In our arid climate leaks show up as wet or unexpected vegetative growth. Inspections at the suspect sites will confirm or reject the suspicion.

Note satellite images can be used as well.

For urban area leaks other methods must be followed because most of the pipelines are covered.

A water balance may be used as a trigger.

Ultrasonic leak detection is now quite common here...

Any leak in a water pipe makes a noise and with fine tuning the leak can be pinpointed quite easily...

Its been used for decades and consists of a trained person walking a round with a long stick and listening to the pipe every so often...

The results are surprisingly accurate - a leak was marked on the pavement outside my house and the guy was telling me how he knew where it was etc...

Next week they dug up the pavement and found the leak, exactly where he said it was....

NOTE - I didn't say that the leak was there before they dug it up, and that the leak could have been caused by the digging - but hey hoo these workmen have to do something to earn their money...

The leak detection on pipelines is a vast subject. It also depends upon the demography of the line route and service, depending upon which you can choose a method.

There are "Software Based Systems integrated with Instrumentations" which help you to detect the line leak in cross country pipe lines. They work out the Flow and Pressure and in terms of line pressure profiling determine the leak point, however the accurace is dependent on lot of variables (leak volume rate and liquid properties included) so in cross country lines you can zero down to a range of 3-5 Kms, and further you have depend on physical survey or ultrasound survey etc.

These System are called LDS (Leak Detection System), you can brouse the net and find no. of links on this.

Pipe for conveying gaseous material there is simple method to detect leak.

Euro helicopter Aloutte 2 & 3 helicopter are assembled around interconnected welded tubular assembly. At one point of the structure a simple small device called visual pressure indicator (called Videopee) is installed after pressurizing assembly with dry nitrogen. If there is a pressure drop due to crack in the welded body structure the pressure indicator will deflate correspondingly and indicate red flag for maintenance crew to ground the helicopter for investigation and check for defect using dye penetrant crack detection NDT.

This method is extraordinarily simple, inexpensive and effective procedure for detecting pressure drop consequent to leak in a tubular structure.

If we are talking Natural Gas there are what we called sniffers out there. Simply drive a rod into the ground, pull out, place the sniffer tube into the hole. It will tell you if there is a leak and the concentration of said leak. More hole's can be made either way on the pipeline if a leak is detected. The closer you get to the leak, the stronger the signal.

As you can see from the posts already here, it matters a LOT what is in the pipe. Water? Natural gas? Crude oil or gasoline? A little more detail, please, and you'll get better responses.

You can followe by ASME B31.3

May be use Pressure reccoder for logging data after hold pressure 1.5 time of Design pressure of pipe