Surface & Underwater Cleaning

1. To remove excessive marinegrowth
2. To prepare a surface for close visual and critical (NDT) inspection
3. To unblock seawater intake.

Removal of the marinegrowth alone is normally adequate for close visual inspection.
Critical NDT inspection, however, requires the removal from the metal surface of everything including paint, coatings, scale, etc. so as to leave a bright shiny metal surface.

High pressure water jets provide the most effective underwater cleaning technique. The operation is commonly called 'jetting'.

Safety

The high pressure water jetting gun is a potentially dangerous tool and needs handling with great care. All divers using such equipment must be trained in its use.
The following precautions should be observed by divers:

1. At no time should there more tha one diver working in an area where jetting is taking place
2. The signal to start the high pressure water supply should only be given by the diver when he is ready to start jetting
3. Under no circumstances should the diver adjust the operating trigger in order to maintain an open position
4. A strong guard should be fitted around the trigger to prevent inadvertent operation
5. The diving supervisor should always be in direct contact with the technician running the pumps who should be standing by his pump whilst it is running. It is imperative that clear communications exist at all times between the supervisor, the pump and the diver.

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