A pore pressure cable mounted along a caissong had loosened. The cable had been mounted with too much distance between brackets, and the influence of waves and weather had made the cable loose from about 10 meters below sea level and some distance up the caisson season. The challenge that was presented was to attach the cable to the caisson season with new clamps.

CAN has long experience with jobs under the deck and in the ripple zone, and has previously worked with both divers and ROVs when work is to be performed underwater. The use of divers and ROV in this case was considered not appropriate as the movements in the ripple zone make this a challenging area to work in. In addition, we believed that other methods could give the customer great cost savings. Our engineers assumed that the job should only be performed by the use of multidisciplinary access technicians from CAN AS.

In connection with the installation of the new clamps, the riser had to be cleaned for marine fouling. The solution was therefore a combined flushing and lifting device that was to first flush the riser and then use it to lift new clamps into place. The flushing and lifting device and brackets were designed by our engineers and fabricated by our partners. An underwater camera was also mounted on the flush and lifting device to monitor and document the work.

We put together a team consisting of security manager and two operators to carry out the assignment. In connection with the flushing of the caisson season, our supplier contacted an operator who handled the high-pressure pump. In addition, our project manager, who is also a certified access technician, traveled out to participate in the execution of the job. The personnel employed on the assignment had been on a similar job for another customer and the experience gained from this job was undoubtedly useful to be part of this project.

The flushing and lifting device was crossed in position under the deck and mounted on the caisson season which was then cleaned. The staples were then lowered one by one to the correct position. Hydraulic bolt pullers with remote release mechanism were designed to mount the clips for the caisson season. These tractors were operated by our operators on deck. To prevent corrosion, CAN Technology had treated the staples with Belzona products prior to shipment. A total of 30 staples were mounted, 15 of them underwater.

The job was done at the end of August / September and although the weather was not the best, the job was done 9 days faster than estimated. Compared to the use of divers or ROV, our method gave the customer a great cost savings.

Customer Feedback:
To give the existing G-20 pore pressure cable a chance to survive future winter storms, the cable has now been clamped in the splash zone, from minus 7 meters below sea level up to below cellar deck level. I would like to highlight the excellent job done by rope access company CAN, by developing a robust clamp design, robust installation tools and procedure, and safely installing in a demanding environment. Essential assistance also from Proserv.

Thank you for your job safely done.