PIPA an independent UK based company specialising in the design, manufacture and assembly of non-evasive and revolutionary pipe inspection, leak detection and cleaning products for the water, gas and oil industries was recently contacted by a water utility client in Hong Kong and its contractor API. The utility had identified a high risk water main that supplied water to an airport, and was laid under the sea bed. The entry point on the bitumen coated steel pipeline was in a water treatment works area. The client needed a long range tethered solution, to check the pipe for leaks and potential blockages.
Challenges
The pipeline is a raw water outlet submarine main that is deeply buried under the sea bed. It is an 1,800 mm diameter pipe operating to 6 to 10 bar pressure which was installed some 35 years ago. The pipe length is 4.4 km which includes several bends.
The client required telemetry to include water temperature, pressure, acoustic leak detection and visual CCTV assessment.
The client discussed options for using alternative methods including:
- Noise correlators – no leaks identified (not accurate on large diameter metallic pipes)
- Free floating devices – Due to the pipe being sited under the sea bed, the client could not risk the system getting stuck or lost within the pipeline
- Using human divers to visually assess the pipe externally. This would have been time consuming and potentially dangerous
The client needed to risk assess the asset and to confirm there were no hidden internal defects or blockages.
PIPA uses technology that includes a pressure rated camera and hydrophone capsule called PLUTO™ tethered to a 5,000 m long cable to give the operator video and recorded audio data during an inspection. The system enters a pipeline via a 150 mm diameter riser, and is fully chlorinated during its Insertion. The system works on a live basis, with no Interruptions to the client’s services. The system can cover a distance of up to 5 km per day.
How it works
The technology requires a pipe entry point and pipe exit point. Upstream a pressure rated camera is inserted to launch a weightless cable and Hydrochute™, this is all sealed within a pressurised housing. The water flow enables the Hydrochute and cable to travel down the pipeline to the required distance. Downstream an expanding net and camera is inserted into the pipe to stop the Hydrochute travelling any further and to remove the Hydrochute and cable during live water conditions.
The PLUTO system is attached to a secondary cable, and this is pulled back through the pipeline using a motorised cable drum, pausing every metre to overlay distance meterage on to the final report. All data is captured onto an internal drive, and a detailed date report is supplied for the client.
Survey results
The results of the pipeline survey included:
- API-PIPA successfully surveyed the entire 4.4 km length in a single insertion, which is believed to be an industry first
- The tethered insertion technology system allowed for precise location of the leaks or defects to be identified and offered a low risk approach to long range pipe inspection
- The acoustic system is very sensitive and was able to pick up small and large leaks
- The operator was able to identify other points of interest, air pockets, joint and bend locations
- Pipe telemetry was successfully recorded to supply the client with acoustic, pressure and water temperature data
The conclusions from the data gained included that it would have been very difficult and expensive for the utility/contractor to confirm issues within the water main. The CCTV and acoustic capability proved indispensable for locating issues and trouble shooting.
PIPA and API completed the inspection in 1 working day which included cable installation and a nightshift to complete the long range pipe inspection survey. The contractor also resolved the ongoing issue by removing the guess work at a fraction of the cost and time that would have needed to be invested in other pipe inspection methods.
A 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 Hong Kong PLUTO project was believed to be an industry first, by delivering a 4.4 km pressurised and tethered pipe inspection survey. PIPA now offers all of its technology to water utility companies all over the World, including remote training and reporting data support. Website: www.pipa-uk.com
