About 5 months ago, Alexander was approached by the Dutch Royal Navy, asking whether Cocoon could also be applied to pressure bottles in the ballast room in a submarine. After an intensive test period, the answer turned out to be ‘yes’ and our boys were able to work in unique circumstances. We tell you everything about it.

The submarine in question is undergoing major maintenance, but has to start sailing again. The pressure bottles – with which the rise and fall are regulated – must be protected with coating. The problem with this is that the pressure bottles have already been placed in the ship, as a result of which the coating must be applied in a very narrow space. The alternative is that the outer skin of the submarine is removed, making the pressure bottles more accessible. Obstacle: this costs about 6000 to 7000 welding hours and is therefore very costly and time-consuming. The Ministry of Defense sought a solution and thus ended up with Cocoon.

Exceptionally short test period

Cocoon would not be Cocoon if we had a solution for that. Even if we had not done it before, we gladly accepted the challenge to be able to preserve the tanks within such a small space. Cocoon was tested beforehand to see how our sprayable PVC adheres in this depth and water load. Not unimportant: there was a considerable time pressure, because the ship had to sail. After an exceptionally short test period of 5 to 6 weeks, the tests were approved. Time to get started!

Conserving ballast tanks in harsh conditions

Dutch submarines consist of two parts: the inner hull in which contains the accommodations, and an outer steel shell. The ballast tanks are located in the gap. You can imagine that applying a coating in such a room is very tedious. But the advantage of the Cocoon system is that it is a sprayable product, which at the same time is seamless. Moreover, it has little overspray, which keeps the rest of the ballast space virtually all clean. The coating adapts to the environment and pulls around the tank. And that is handy, with a tank measuring a length of 2.40 meters and a diameter of 1 meter.

Meanwhile all pressure bottles have been coated and we can complete this very unique assignment. The ship will sail again at the end of January / beginning of February, with coated tanks.