How do you deal with rotten seawater pipes?
How many times has a docking superintendent inspected a large, expensive seawater pipe, with a pinhole or localized damage, and instructed the dockyard to renew the entire pipe?
Refurbishment of a DN700 Manifold Seawater Pipe
99% of the old pipe is sound, but every day docking superintendents throw away the old pipe and tell the dockyard to make a new pipe.Does this strike anyone as being wasteful?
The truth of the matter is that until Irwin Rotational lining began offering pipe refurbishment services in China dockyards, renewing the entire sea water pipe was the only option. Pipe refurbishment is a heavy industrial process that is done in Irwin Rotational Lining’s specialized workshop.
Removing old pipes’ coating
Ultrasonic thickness testing
The condition of the pipe as received was poor with the original rubber coating missing in most areas. Heavy corrosion and pitting of the steel were observed.
The old coating and paint are removed in a cleaning oven, the pipe is ultrasonically inspected, localized welding repairs performed, grit blasting conducted and then the pipe is lined with a 2-6 mm thick layer of polyethylene (PE) in our customized lining ovens. The old pipe is now better than new at a fraction of the cost of renewing the pipe. Entire cooling and ballast systems can be refurbished in less than 72 hours, meeting the tightest docking schedules.
Rotational lining in our custom built oven
The biggest advantage of refurbishing pipes is cost. Since we are re-using 95%, or more, of the old pipe, it is much cheaper to refurbish the old pipe than fabricating and coating a new pipe. You know the refurbished pipe will fit since it is the same pipe. The investment in the refurbishing process that creates a refurbished pipe that is better and longer lasting than the original pipe is Irwin’s proprietary rotational lining process. The old pipes often have pitting on the inside that creates a surface profile unsuitable for re-coating by other coating processes.
By applying a uniform 2-6 mm layer of PE to the inside of the pipe, we fill in these pits and the result is a smooth finish that reduces friction losses and inhibits marine growth. The pits even improve the performance of the lining by improving the adhesion. We are using the old steel pipe as a mold and building a new plastic pipe inside. With the money we save by recycling the old pipe, we can afford to concentrate on over engineering the coating with the result that the refurbished pipe will last longer than the original pipe.
Job completed in less than 36 hours! Beautiful results!