Cathodic Protection Network
Case Study 4
Whilst working for Shell-BP Development Corporation (Nigeria), in the position of ENGE 18 in charge of the corrosion control section Port Harcourt, Rivers State, Nigeria I was responsible for all corrosion related matters in the Eastern Division.
Using my own survey techniques I was able to correctly predict that there was active corrosion to main Swamp Pipeline passed under Bonny Creek to Bonny Export Terminal.
Following my successful prediction of a corrosion failure at the Krakama Delivery Pipeline and the successful arresting of corrosion leaks recorded at Ekulama and Agbada, I was given full finance to put into place a Cathodic Protection installation at Cawthorne Channel.
The Electrical Engineering Department and their contractors were unable to undertake the work and I was authorised to get the job done at all speed. Supervising four local contractors and working in tidal swamp conditions we constructed a 300 amp 50 vertical anode groundbed system 2miles into inaccessible mangrove swamp. We built a roller railway of wooden sleepers to hand move a 3 ton transformer rectifier for a mile and then used a rocking mechanism to raise it 2 meters above high, high tide level into position on a pipeline riser platform. At the same time I had a team of local contractors laying one mile of 70mm, armoured cable which I wired to a 3 phase electrical supply generator in Cawthorne Channel Flowstation. this whole operation was successfully carried out between tides because barges could not reach the groundbed site.
We used dug out canoes to move through the mangrove swamp and very well rehearsed local labour to achieve completion.
The following day I commisioned the system successfuly from the Cawthorn Channel Flowstation and went on by helicopter to Bonny Terminal to check the readings at that end of the pipeline. As I was being flown over Bonny Creek I inspected the pipeline markers on either side of the water. The tide was ebbing and I saw a small plume of rainbow contours some distance downstream but clearly pointing to the pipeline crossing. I reported this to head office and was told to return to base where I was joined by the Managing Director and the Head of Engineering.
They were of the same opinion as myself and immediately organised a diving crew to inspect the pipeline.
A couple of days later I was asked if I could give an accurate position of the leak as all other techniques on offer internationally had failed. I joined the diving crew headed by Malcolm Frost of Solus Schall and his diving team leader Arthur Jones. We had a barge anchored in the centre of Bonny Creek but the difficulty was that visibility from half meter down was nil. It was pitch black and lights did not help at all as Niger Delta silt was the problem.
Using one of my techniques adapted to waterbound operations I was able to drop a wieght directly onto the leak and the divers followed the line down from the marker buoy. They were able to describe the damage in detail by feel alone.
I have photographs of some of the equipment which was designed by the divers to try to repair the leak. Unfortunately this didn't work and the whole of the swamp operations were shut down for six months while a replacement crossing was constructed by McDermot International.
The cost can be imagined and had I been six months earlier the leak could have been stopped as it was at On the flowlines Ekulama 14 and Ekulama 17. During my return to Nigeria 18 years later Dwonomwi Abidiak, one of my Shell Junior Engineers, told me that these two pipelines had never leaked again and that I was known in the region as the father of cathodic protection.
Details of the techniques that I used during these investigations can be acquired during Cathodic Protection Network Training Course. Accreditation requires that you could not possibly make the mistakes that I found at this location.