API was recently contacted by a water utility client in the UK. The utility had identified a leak on a 1,200 m section of 1,000 mm diameter pipeline. The pipeline had been tested over a period of 18 months and would not hold pressure above 10 bar.
The pipeline was installed in wet ground conditions and the pipe was located close to marshland in a water treatment work area. Due to the pipeline bury depth and location, the client tried using traditional techniques using several specialist leak detection companies; however no company could pinpoint the leaks location, which created several dry dig excavations, along with a very expensive delay to the project.
Challenges
Challenges posed by the leakage problem included:
• The pipeline is a water treatment outlet main and deeply buried.
• The pipeline is a 1,000 mm diameter pipe with 16 bar pressure test required, and was installed over 18 months ago.
• The client utilised several ‘specialist’ leakage teams and searched for leaks over several months with the following methods:
- Noise correlators – no leaks identified (not accurate on large diameter metallic pipes)
- Listening stick- Pipeline was deeply sited below ground so this technique not feasible
- Tracer gas – ground structure and conditions resulted without any results
- Temporary bypass and flowmeter- this identified a leak, however did not pinpoint its location
This had a major knock-on effect, as the client cannot proceed with a localised repair solution, and also may require a road closure at the treatment works entrance.
PIPA uses technology that includes a pressure rated camera (CommissioncamTM) and hydrophone capsule (PipepodTM) tethered to a 2,000 m cable to give the operator video and recorded audio data during an inspection. The system enters a pipeline via an 80 mm to 150 mm diameter riser; the system works on a live or pressurised basis, and can cover a distance of up to 2 km per day.
The cable is installed using a tethered swab; once the cable is installed the sensors are rated to 20 bar and offer pipe installation companies a fail-safe when pipe issues occur:
- The Pipepod sensor accurately detects leak location in all pipe materials including plastics
- The HD camera sensor inspects pipe condition to offer a quality control system to check the pipe has been correctly cleaned
- The pipe is free of air pockets
- Check gasket and joint alignment
The technology is the only long range new main inspection system on the market being fully battery powered and only requires a 2-man team for its implementation.
Survey results
PIPA successfully identified the leak at 413 m into the pipe. The tethered insertion technology system allowed for precise location of the leaks to be identified with the acoustic system being very sensitive and able to pick up small and large leaks. The operator was able to identify no other leaks with joints identified in close proximately to each other and the camera system was used post pipe repair to validate the pipe was clean and free of debris
It would have been very difficult and expensive for contractor to find the remaining issues within the water main. The CCTV and acoustic capability proved indispensable for locating issues and trouble shooting. PIPA completed the inspection in 1 working day, and in total successfully identified and located 1 now verified leak. The contractor resolved the ongoing issue by removing the guess work at a fraction of the cost and time that had been invested in other methods in previous months. The client estimated a capital spend of £250,000 was invested in the project prior to the Pipepod Hydrostatic and Commissioncam being used.
An API-PIPA representative said: “The project was a great success. Ideal due to pipe location and material and also a great case study for our company. The contractor had exhausted all other pipeline inspection avenues, and was more than relieved when we offered a solution. The Pipepod and Commissioncam system removes any delays on all new pipe installation projects, installing our unique cable as part of the swabbing procedure is a game changer for the industry!”
