Biofouling on Offshore Installations — An Impact and Monitoring Assessment
ONGC — a state owned company is engaged in exploitation of natural hydrocarbons from the east and the west coast of India, both near and far shore, from deep and shallow waters using both fixed and floating structures. The occurrence of marine fouling on fixed offshore structures has attracted interest because of its potential adverse effects on structural loading and corrosion. The biofouling is a complex biological process, their growth and attachment on offshore platforms is a universal phenomenon. The major biological growth of foulers do not differ much in tropical and other waters. An average growth of 5–10 cms. increases the structural load by about 5.5 to 11.5% necessiating the periodical mechanical removal, which appears to be the solution so far, for fixed offshore structures. This process is cost intensive and is a structural weakening process.
Almost all the known preventative methods envisage use of toxicants. Their conventional application though is effective, but have short life span. The present study deals with analysis and impact of biofouling phenomenon, recent development in preventive methods and evaluation of some prospective antifoulants.
A new concept based on continuous release of toxicants, ensuring long time protection has been attempted. Two sets of test pannels of standard dimensions of commonly used metals in offshore structures (ASTM-A-36 and API-2H) were installed at test platform for two different time intervals. The deposition on control pannels and members of structures found to be moderate yet quite significant. The slow release of copper ion was found to have considerably reduced the attachment and growth of biofoulers. The results are being evaluated for long exposure.
KeywordsSplash Zone Test Platform Offshore Structure Offshore Platform Test Coupon
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