Removing Marine Growth Using an ROV with Cavitation Technology
- Andrew Restivo (Oceaneering International, Inc.) | Michael Brune (Oceaneering International, Inc.)
- Document ID
- Offshore Technology Conference
- Offshore Technology Conference, 2-5 May, Houston, Texas, USA
- Publication Date
- Document Type
- Conference Paper
- 2016. Offshore Technology Conference
- 4.5 Offshore Facilities and Subsea Systems, 4.5.10 Remotely Operated Vehicles, 4.5 Offshore Facilities and Subsea Systems, 4.5.3 Floating Production Systems, 4.5.5 Installation Equipment and Techniques, 4 Facilities Design, Construction and Operation, 7.2.3 Decision-making Processes
- ROV Skid, Marine Growth Removal, Cavitation
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- 114 since 2007
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Marine growth on the submerged hull of a floating offshore installation can prevent the effective inspection of external hull plating, weld, and coating. Subsequently, several countries throughout the world have established regulations addressing inspection and maintenance of structures in their offshore waters. Marine growth removal using high-pressure water is very common in the industry, but high-pressure water can easily damage and strip away anti-fouling coating. This smooth, slippery, and low-friction coating is what prevents organism growth from attaching to a subsea surface.
The objective of this project was to develop the technology necessary to remove marine growth from offshore structures using an ROV-operated system employing controlled cavitation erosion without damaging the anti-fouling coating. An ROV-mounted skid fitted a custom cavitation nozzle has been developed to perform this work.
A detailed quality test plan was created to analyze the system for subsea use for an operator in Angola. The primary goals of the Cavitation Water Jet System (CWJ) test plan were threefold:
Determine, for all nozzle sets operating at their rated pressure and flow, the optimum standoff distance, attack angle, and traverse rate necessary to remove simulated marine fouling without damaging the underlying coatings.
Determine the reaction forces generated from the lance and rotary head when operating at their rated pressure and flow rate. Since the rotary head can be fitted with two nozzle types operating at 8000 PSI @ 15 GPM and 5500 PSI @ 21 GPM respectively, the rotational speed for both was measured.
Determine the performance of system at different water depths.
The system passed quality tests and inspection, and was successfully used for FPSO hull cleaning in Angola in 2014-2015.
|File Size||6 MB||Number of Pages||23|