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ANTI- FOULING

ANTI- FOULING. What is marine fouling?. The growth of shell, barnacles, tubeworms, seaweed and microorganisms on sea water immersed surfaces like ship hulls. Fouling produce roughness, reduce speed and increase turbulent flow, acoustic noise, drag and fuel consumption.

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ANTI- FOULING

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  1. ANTI- FOULING

  2. What is marine fouling? The growth of shell, barnacles, tubeworms, seaweed and microorganisms on sea water immersed surfaces like ship hulls. Fouling produce roughness, reduce speed and increase turbulent flow, acoustic noise, drag and fuel consumption. 10 microns increase in hull roughness can result in 1 % increase in fuel consumption!

  3. Trading area Marine fouling is temperature related

  4. Vessel activity Type, severity and extent of marine fouling depend on vessel trading pattern, speed, activity and geographic location.

  5. History The early Phoenicians nailed copper strips to their ship’s hulls to prevent fouling. Admiral Nelson made use of copper plating on the hulls and his war ships were far more maneuverable than those used by the French (1805), a tactical advantage he used to obtain a victorious outcome. Antifoulant biocides have included DDT, phenyl-mercury, pentachlorophenol, organolead, arsenic compounds and copper mixed into binders of gum rosin, chlorinated rubber, vinyls, acrylate.

  6. Tributyltin TBT High microbiological and fungicidial activity makes TBT derivates effective biocides and very toxic to a wide range of marine organisms. Used since the early 1970’s in antifouling paints. Estimated over 70% of the world’s ocean going fleet were painted with TBT self- polishing based paints. Superior fouling prevention and fuel savings.

  7. Self-polishing SPC antifouling paint TBT biocide chemically bonded in a copolymer paint, allowing thick paint films with controlled, uniform release of the biocide to the surface. Effective prevention of fouling and reduction of frictional drag. 92% of TBT SPC- painted ships show low fouling with life- time of 5 years +

  8. TBT based antifoulings perform well! TBT acrylate after 60 months service

  9. Test facility (Raft)

  10. Static antifouling test panel

  11. Marine fouling

  12. Rotor test facility

  13. Rotor test panel

  14. Regulations Research has indicated that TBT may be responsible for the weakening of oyster and mussel shells as well as slowing the growth of various species of aquatic snails (imposex). These concerns have led to regulatory measures around the world resulting in a Ban on TBT

  15. Restrictions on the use of TBT based AF In the US, the 1988 Organotin Antifouling Paint Control Act restricted the use of TBT-based antifoulants to ships larger than 25 mtrs. in length or those with aluminium hulls. This act also restricted the release rate of TBT. Japan unilaterally banned TBT antifouling in the early 1990’s. In 1990, the International Maritime Organization (IMO) of the United Nations’ Marine Environment Protection Commitee (MEPC) adopted a resolution that recommended governments adopt measures to restrict the use and release rate of TBT-based antifoulants. The MEPC is made up of IMO member countries with shipping interests.

  16. IMO proposal “A worldwide ban on the application of TBT (tri-butyl tin) antifouling systems on ships by1st January 2003” “A ban on the presence of TBT antifouling systems on ships by1st January 2008”A sealer coat can be used to overcoat existing TBT-based antifouling Urges all parties involved to “refrain from the production, sales, marketing and application of antifouling systems containing organotin compounds acting as biocides from 01/01/2003”

  17. IMO update • 5-year dockings will require tin-free paint for 2003 • The treaty needs 25% of tonnage and 25 countries to ratify it. It becomes law 12 months after this. • EU will try to keep to the deadline of 1/1/2003 for EU flagged tonnage • USA will make legislation retroactive to 2003 • International Chamber of Shipping in London has “recommended that ship operators should observe the recommended prohibition date with effect from 1 January 2003” • So plan to use TBT-free paint from January 2003

  18. Main antifouling technology • 1. Copper based (tin-free), Biocide* type • 1st generation Self-Polishing - Hydration type • 2nd generation Self-Polishing - Hydrolysis type • 3rd generation Self-Polishing - Hydrolysis type • * Biocide – a chemical which is toxic to fouling • Note: Hydrolysis mechanism is like TBT type • 2. Copper-free, tin-free, Biocide* type • 3. Biocide* Free Type • Foul release, Silicone rubber type • Others

  19. Self-Polishing Polymer Biocide

  20. Release Controlled release of biocide ions Ionized layer of highly concentrated biocide Retention Efficient ionization of biocide Renewal Keeping biocide activity : Biocide Ion Self-Polishing

  21. Self-Polishing

  22. Self-Polishing

  23. Mechanisms for self-polishing • 1. HYDRATION type, self-polishing • Hydration – where water physically erodes the antifouling • Also called ablative, eroding, controlled depletion and 1st generation tin-free 2. HYDROLYSIS type, self-polishing • Hydrolysis – where water chemically reacts and dissolves the antifouling • 2nd and 3rd generation tin-free antifouling

  24. Mainstream copper based tin-free technology Tin-Free Hydrolysis 2nd Generation Tin-free Ablative 1st Generation Tin-free Ablative/ Fibrous type TBT Antifouling Tin-Free Hydrolysis 3rd Generation

  25. Hydrolysis gives a consistent (linear) polishing rate 2nd generation (Green line) and 3rd generation (Blue line) demonstrate the excellent polishing performance just like TBT-AF (Red line) in below chart The indoor rotor: 15 knots,25°c, natural sea water

  26. Hydrolysis gives a consistent (linear) leaching rate of biocide

  27. Lower Absorbance of Water in the Resin means higher performance - the reaction is controlled at the surface Tin-Free Hydrolysis 3rd Generation Tin-Free Hydrolysis 2nd Generation Tin-Free Hydration 1st Generation TBT Antifouling

  28. Performance of Antifouling Paints (%age of ships free from fouling) HYDROLYSIS Antifouling 3rd Generation tin-free – Organo-Silyl Acrylate 2nd Generation tin-free – Metallic Acrylate HYDRATION Antifouling 1st Generation - Eroding, ablative, gum rosin, controlled depletion 95%=TBT 90% 70 - 85% Performance

  29. Summary - Antifouling Performance The performance of an antifouling is deepen-dent on long term, consistent control of the polishing mechanism. This is best achieved with the hydrolysis mechanism. 3rd generation>2nd generation>1st generation Costs per m²: 4 : 2½ : 1

  30. Foul Release Coatings Benefits • Environmentally friendly • 5-years between dockings • Smooth surface and potential fuel savings • Easily re-coated • Self-cleaning or for slow vessels, easily cleaned Disadvantages • High cost • Masking-off of topsides • Careful application is required for silicones • Repair requires more care with preparation

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