Once the ROV places weights on the tank pistons, heavy acid is injected at multiple points around the mandrel. With heavy acid having higher density than water, water is displaced and forced out via two pressure relief valves.

The system can be left in place to soak for extended periods, while other ROV operations are performed. Seals minimise the seawater dilution of the injected acid to ensure an effective clean. The cap has a simple, robust design, resistant to the corrosive effects of the saltwater and cleaning acids.