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Qualitative method for antifouling

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  • 1. Biosciences, Biotechnology Research Asia Vol. 7(2), 675-688 (2010) Qualitative method for antifouling long life paint for marine facilities or system O. SULAIMAN¹, A.H. SAHARUDDIN¹, A.S.A. KADER² and W.N. WAN NIK¹ ¹Department of Maritime Technology, University Malaysia Terengganu, (Malaysia). ²Department of Marine Technology, University Teknologi Malaysia (Malaysia). (Received: August 05, 2010; Accepted: September 22, 2010) ABSTRACT Fouling is a major problem to shipping industry. Hull fouling reduces the fuel efficiency and speed of affected ships, increase in frequency of ship dry dockings, reduces propeller efficiency and accelerated corrosion rate. Antifouling paints are used to coat the underwater area of ships to prevent organisms such as algae and molluscs attaching themselves to the hull of the ship. As a result, antifouling paints which are alternatives to TBT systems such as controlled depletion systems (CDPs), tin-free self-polishing copolymers (tin-free SPCs) and foul release systems were developed in marine industry. However, most of these paints cannot last for long because misapplication. Paint is not a finished product until it has been applied and dried on an appropriate substrate at the designed performance film thickness. High performance paint systems are especially sensitive to misapplication and knowledge of the paint characteristics. Also recommended film thickness is vital to obtain optimum results to improve paints performance and reduce maintenance cost. Therefore, proper application is critical to the performance of the paint system. This paper presents the result of study made on the problems of fouling on ship hull structures and deduced a qualitative model for ship paints application in order to prolong the life span of antifouling paint. Key words: Antifouling; application; hull fouling; paint; marine system. INTRODUCTION of marine organisms that swim around until they find somewhere to settle and grow. Smooth surfaces Performance of ships depends on their are particularly attractive to many of these creatures,speed and power generated. Likewise, economic and are quickly encrusted. This slow down ships inand efficiency of ship operation is achieved at seaways, block pipes and speed up corrosion. Thisoptimum speed, power and according to frequency study focuses on the problems of ship hull foulingof dry docking of ship. Hull fouling poses a lot of which hull fouling reduces fuel efficiency and speedhindrances to design power and efficiency of ship. of affected ships, consequently increases theirFouling refers to the accumulation of unwanted operating costs due to the increase in frequency ofmaterial on solid surfaces in an aquatic environment. ship dry docking. It also reduces propeller efficiencyThe fouling material can consist of either living (Kan et al., 1958; Mosaad, 1986) and acceleratesorganisms (biofouling) or a non-living substance corrosion (Edyvean, 1982).(inorganic or organic). In order to lessen hull fouling, antifouling Marine fouling is a perennial problem for paints are used to coat the bottoms of ships tovessels, ports and anything kept in the sea for a prevent organisms such as algae and molluscsperiod of time. The sea is teeming with the tiny larvae attaching themselves to the hull, that result to the
  • 2. 676 Sulaiman et al., Biosci., Biotech. Res. Asia, Vol. 7(2), 675-688 (2010)slowing down of the ship and thus increasing fuel the surface. Paint is not a finished product until itconsumption. The new IMO convention defines has been applied and dried on an appropriate‘antifouling systems’ as ‘a coating, paint, surface substrate at the designed performance filmtreatment, surface or device that is used on a ship thickness. When the paint is applied to the exteriorto control or prevent attachment of unwanted layer to a ship hull, it is subject to a variety oforganism’. Biocidal anti-fouling paints have been parameters that can degrade the paint and reduceapplied to the bottoms of ships for decades. The its useful life-span. These parameters need to bepaints slowly leach into the water, killing anything taken into consideration during ship paintsattached to the ship hull, but leachates have been application. Thus, ship paints application proceduresfound to accumulate in harbors and the sea. are very impor tant in order to enhance the performance or quality of antifouling paints. The Among all the different solutions proposed parameters which need to be considered duringthroughout the history of navigation, tributyltin (TBT) application of the paints to the ship hull includepaints have been one of the most effective surface preparation, paint application, paintdeterrents to hull fouling organisms, but studies have materials, curing time, environmental conditions,linked TBT accumulations to deformations in oysters locations, personal quality, inspections and others.and sex changes in whelks. As a result, restrictionson the usage of TBT in vessels were imposed. The The performance of any paint coatingInternational Maritime Organization (IMO) adopted depends on the correct and thorough preparationthe Antifouling Systems (AFS) Convention in 2001. of the surface prior to coating. The most expensiveThe Convention called for a global ban on the and technologically advanced coating system willapplication of TBT-based antifouling paints by 1st fail if the surface preparation is incorrect orJanuary 2003 and the prohibition of the presence incomplete. Additionally, methods of applying theof such paints on the surface of vessels by 1st paints are by brush, roller, conventional (air) spray,January 2008 (IMO, 2005). National bans on the conventional (pressure pot) spray and airless spray.use of the TBT paint will result in an increased hull Although the application methods are veryfouling, unless environmentally friendly replacement important, the application technique or skills ofpaints are accepted by the shipping industry. personnel also play a vital role. When applying marine paints, the most important factors to The paint industry has been urged to consider are the condition of the substrate, thedevelop environmental friendly TBT-free products surface temperature, and the atmosphericable to replace the TBT-based paint that yield the conditions at the time of painting. Appropriate shipsame economic benefits and cause less harmful paint materials can effectively prevent attachmenteffects on the environment. There are controlled or accumulation of fouling on the ship hull bottom.depletion systems (CDPs) and tin-free self-polishing Furthermore, inspection by the coating inspector iscopolymers (tin-free SPCs). CDPs are upgrade of necessary to make sure the coating is properlytraditional soluble matrix technology by means of applied.modern reinforcing resins. The reaction mechanismsare assumed to be equivalent to those of This study seeks to examine the relatedconventional rosin-based AF paints. The tin-free issues of antifouling (AF) paints, ship paintsSPCs are designed for the same reaction application and aims to deduce fouling preventionmechanisms with sea water as tributyltin self- systems and enhance the performance ofpolishing (TBT-SPC) paints. antifouling paints. This includes the study of biology of the fouling process, historical development of AF There is another type of antifouling paint paints and also the proper way for ship paintsthat may replace the TBT-based antifouling paints application. The historical description leads to awhich is foul release systems. Foul release systems discussion of tributyltin (TBT)-based systems, tin-are non-toxic and made of silicone elastomers of free biocide-based and non-toxic alternativeslow surface energy. This low surface energy inhibits replacements. Proper paint application is critical tothe ability of fouling organisms to attach strongly to the performance of the paint system. This study
  • 3. Sulaiman et al., Biosci., Biotech. Res. Asia, Vol. 7(2), 675-688 (2010) 677will use historical data of antifouling paints to From the improved ship paint applicationdetermine the parameters for ship paints application. flow chart above, I have added one step from theFinally, a qualitative model for ship paint application previous flow chart in order to optimize the existingto enhance the performance of antifouling paints is procedure. This improved flow chart can make thededuced. paint application become more comprehensive, concise and efficiencyMethodology The model design is for the ship paint Vessel comes into dockapplication procedure. This is produced through Since it is a class requirement, for eachinterview carried out with the ship yard personal in vessel needs to come into dock to undergo theMMHE and M-Set. Data are collected from bottom survey inspection of its underwater areaPainting and Blasting Department, reviewed about every two and half years. Vessel will be put in theship painting process and interview with the dry dock upon arrival in the shipyard. The vesselClassification Society and Paint Maker in order will be moored into the dock and when it hadto get the further information. This is to make sure successfully sat on the keel blocks, the water in thethe procedure is compliance with the standard dock will be pumped dry.and IMO requirement. Data is analysed byconsidering the whole ship painting process and Underwater Hull Pre-cleaning Assessmenthow the ship painting procedure is carried out The step for the inspection process is toaccording to the standard. And the analysis leads conduct an underwater assessment of the foulingto deduce a qualitative model for ship paint growth that has occurred since the last inspectionapplication procedure. and evaluate the coating condition. This will be completed before any hull cleaning is performed. RESULTS AND DISCUSSION Normally, ship hull can be divided into 6 quadrants as showed in Fig.1. The six quadrants are: I - The model is produced with the intention starboard forward, II - starboard aft, III - port aft, IVof giving a guideline for all level of personnel on the - port forward, V - starboard waterline, and VI - portstandard of workmanship in the ship repair division; waterline.especially, the blasting and painting parts in orderto satisfy ship owners and classification societies. Fouling AssessmentThis model indicates the elements accuracy to be Fouling growth on each boat hull will bekept in the process of blasting and painting repairs evaluated on a 0 – 5 scale. 0 represents the optimalor modifications and the finished quality obtained. condition and 5 the worst condition. Table 1 determines the numeric ratings and provides a description of what type of fouling growth is The model is developed from several associated with each rating. The paint maker’sreferences, historical data and case study related inspector will record the fouling rating for eachto antifouling paints. The model can serves as a quadrant and provide any additional observationsguideline of the standard of workmanship for or comments, such as noting the type of foulingpainting process that mitigates fouling of ship’s hull. present on the hull surface.. The quality of the end product relies on the wholeship paint application process. Thus, we must always Coating condition assessmentkeep in mind that “Quality is built in the process, Coating condition for the entire hull neednot in the inspection”. to be evaluated based on Table 2 which identifies the rating scale of coating condition. The colour of From the existing ship paint application undercoat also need to be recorded when theabove, I found the gaps to improve the existing coating was applied to the ship hull. Ratings of 1-3procedure. The improved ship paint application flow represent antifouling painted surface appearancechart is showed in 3.2. This flow chart can make associated with normal physical wear due tothe paint application becomes more efficient underwater cleaning action or hydrodynamic effects.
  • 4. 678 Sulaiman et al., Biosci., Biotech. Res. Asia, Vol. 7(2), 675-688 (2010)Ratings 4 and 5 indicate either excessive cleaning standard procedures requirement. If contaminantsactions or blistering due to internal failure of the such as loose rusts, oil, grease, dir t, salts,paint system. chemicals, dusts, etc. are not removed completely from the surface intended for coating, the paintSurface Preparation adhesiveness as well as cohesiveness and its Good surface preparation is one of the quality would be affected. Osmotic blistering wouldmost important process of the entire coating also occur resulting in premature failure of theprocedures, as great percentage of coating failures coating in service. There is no paint system thatare usually associated with poor surface would give optimum performance result over apreparation. All paint systems will fail prematurely if poorly prepared steel surface.the surface preparation is not done according to Table 1: Fouling rating scaleRating Fouling Growth0 No silting, biofilm or fouling growth present.1 Light silting or biofilm. Little to no discoloration; Paint surface still clearly visible beneath.2 Heavy biofilm; Light to moderate silting as indicated by discoloration (a solid, discernible, physical layer); Painted surface may be slightly obscured.3 Low to medium levels of fouling present; Dark algae impregnation; Hard growth may be present (tubeworms, barnacles, bryozoans, etc.); Painted surface definitely obscured.4 Medium to high levels of fouling present; Hard growth present, such as tubeworms, barnacles, bryozoans, etc.; Macrofoulers may include mature forms that may be densely grouped; Paint surface no longer visible beneath fouling in areas.5 High levels of fouling present; Lengthy, soft algae and hard, tube worms and possibly barnacles impregnating the coatings; Macrofoulers may be densely grouped; Coral** growth can be seen to extend out from the hull; Paint surface no longer visible beneath fouling.*0 is best condition; 5 is worst condition; ** Coral is the local term used for limestone tubes of worms that grow on thecoating’s surface. Table 2: Coating condition rating scaleCoating Condition Coating DescriptionRating1 Antifouling paint intact, new or slick finish. May have a mottled pattern of light and dark portions of the original paint colour.2 Shine is gone or surface lightly etched. No physical failures.3 Physical failure on up to 20% of hull. Coating may be missing from slightly curved or flat areas to expose underlying coating. Coating has visible swirl marks within the outermost layer, not extending into any underlying layers of paint.4 Physical failure of coating on 20-50% of bottom. Coating missing from slightly curved or flat areas to expose underlying coating. Coating missing from intact blisters or blisters which have ruptured to expose underlying coating layer(s). Visible swirl marks expose dunderlying coating layer.5 Physical failure of coating on over 50% of bottom. Coating missing from intact blisters or blisters which have ruptured to expose the underlying coating layer(s). Visible swirl marks exposed underlying coating layer.
  • 5. Sulaiman et al., Biosci., Biotech. Res. Asia, Vol. 7(2), 675-688 (2010) 679Hull cleaning the level of salt and to make sure that salt content There are various methods available for is at minimum level. Normally, salt test is carriedcleaning and preparing steel surfaces prior to out by using “Bresle kit sampler”. Fig. 2 showed thepainting. The choice and methods of surface flow chart of salt test measurement by “Bresle kitpreparation would depend on the location where sample”.the intended area of the vessel is required and theavailability of equipment to be used. Hull cleaning Condition of ship hull (side shell area) prior toincludes hard scrap and fresh water washing. Hard grit blastingscraping shall be carried out to remove slimes, Next, the Owner’s representative will markweeds, shells, barnacles, etc. Besides that, out the corroded area for blasting based on rustapproved detergents shall be used to remove any grade and shall discuss it with the Yard’s Paintingoil or grease present on the hull. executive. There are four types of rust condition using Swedish Standard which listed in Table 4.Hull cleaning standard by fresh water When all parties had agreed on the total blast area Surface preparation by using fresh water and the blasting grade, a Proposed Side Shellcan be divided into 4 levels. Table 3 is the levels or Blasting and Painting Area shall be signed andcategories for fresh water surface preparation: endorsedSalt test Shipyard shall draw up a work schedule The purpose of carrying out the salt test based on the agreed areas and instruct the blastingis to prevent coating failure due to effects of salt contractor to proceed with the blasting works. Theelements on the surface before coating. In order to blasting time of inspection is usually divided intoprevent the defect, salt test is carried out to measure two sessions, once before noon and another late in Table 3: Categories for fresh water surface preparationFresh Water Washing/Pressure Cleaning QualityLow Pressure Water WashingPressure: It can remove surface salts, dust and loose surface debris.Less than 68 bar (1000 psi)High Pressure Water Washing For 68-204 bar (1000-3000 psi)Pressure: It can remove salts, dirt, loose coatings and leached layerBetween 68-680 bar (1000-10000psi) of antifouling coatings. For 204-680 bar (3000-10000psi) It can perform selective removal of coatings and intact coatings.High Pressure Hydro-Blasting (Water- It can remove all existing old paint or heavy rust. It scalesJetting) to WJ 3 (Water jetting standards NACE 5/ SSPC-SP 12)Pressure: Between 680-1700 bar to a uniform matt finish with at least two thirds of the surface(10000-25000being free of all visible scale) and the remaining one-third containing onlyresidues (except mill psi) randomly dispersed stains of previously existing rust, coatings and foreign matter.Ultra High Pressure Hydro-Blasting It can remove all existing old paint or heavy rust. It scales (Water Jetting) to WJ 2 hydro jetting standard of uniform matt finishPressure: with at least 95% of the surface area being free of allAbove 1700 bar (25000 psi), but previously existing visible residues and the 5% normally 2000-2800 bar (30000- containing only randomly dispersed stains of rust,40000psi) coating and foreign matter.
  • 6. 680 Sulaiman et al., Biosci., Biotech. Res. Asia, Vol. 7(2), 675-688 (2010)the evening. This is to allow sufficient time for the Copper grit is one of the blast media widelyblasters to produce a larger blast area so that when used for blasting in shipyard and is obtained asthe paint is mixed and applied, there will not be cooper slag waste from melting the copper metalmuch wastage for the coverage. at a very high temperature. It is a by-product and is often referred to as hard coarse-grained silicieousGrit blasting sandstone. This is the base for grit and can be found Grit blasting is the commonly used method or prepared in different sizes for different types offor preparing a surface for the application of paint. blasting known as grit blasting. It usually comes isWhen properly carried out, grit blasting can remove sizes ranging from 830cc (meshes) and 1030cc butold paint, rust, salts, fouling, etc., and provides a most shipyard prefers the former over the lattergood mechanical key (blast profile) for the new because of its coarseness and larger size in ordercoating. to achieve a higher blast profile on the steel substrate. Table 4. Rust condition using Swedish Standard Steel surface largely covered with adhering mill scale with little, if any rust.Rust Grade A Steel surface has begun to rust and from which mill scale has begun to flake.Rust Grade B Steel surface on which the mill scale has rusted away or from which it can be scraped, but with slight pitting visible under normal vision.Rust Grade C Steel surface on which the mill scale has rusted away and on which pitting isRust Grade D visible under normal vision. Table 5: Preparation grades for steel surfaces using blast cleaning Brush Off Commercial Near-White Metal White Metal SSPC SP 7 SP 6 SP 10 SP 5 NACE No. 4 No. 3 No. 2 No. 1 SWEDISH Sa. 1 Sa. 2 Sa. 2½ Sa. 3
  • 7. Sulaiman et al., Biosci., Biotech. Res. Asia, Vol. 7(2), 675-688 (2010) 681 Table 6: Ship side coating thickness range Locations/Areas Surface Preparation DFT range, µm Topside 1. High pressure fresh waterwash 200 – 400 (epoxy) Boot Top (3000 – 5000 psi) 150 – 300 (epoxy) 2. Grit blast Sa 2.0 or Sa 2.5 75 – 100 (tie coat) 150 – 200 (antifouling) Vertical Side 200 – 300 (epoxy) 75 – 100 (tie coat) 250 – 300 (antifouling) Flat Bottom 175 – 300 (epoxy) 75 – 100 (tie coat) 100 – 200 (antifouling) Propeller 375 – 400 Rudder 500 Table 7: Typical ship paints propertiesPaint Type Drying Mechanical Cosmetic Overcoat- Area of Use Mechanism Properties Properties ability Underwater Above WaterAcrylic Physical Moderate Very Good Good / (antifouling) /Alkyd Oxidative Moderate Good Good - /Bituminous Physical Poor ND A Very Good / -Chlorinated Physical Moderate Moderate Very Good / /RubberEpoxy Chemical Cure Very Good Poor Poor / /Epoxy-Ester Oxidative Moderate Moderate Good - /Epoxy-Tar Chemical Cure Good ND A Moderate / -Polyurethane Chemical Cure Very Good Very Good Moderate - /Polyurethane-Tar Chemical Cure Good ND A Moderate / -Vinyl Physical Good Good Very Good - /Vinyl-Tar Physical Moderate ND A Very Good / -Zinc Silicate Moisture Cure Very Good ND A Very Poor - / Self to Self Good with epoxiesN/A = Not applicable Table 8: Average Hull Roughness (AHR) value for antifouling paints Types of paint fouling control technology Average Hull Roughness (AHR) Controlled Depletion Polymer (CDP) 40 microns/year TBT Free Self Polishing Copolymer (SPC) 20 microns/year Hybrid TBT Free Self Polishing Technology 30 microns/year Foul Release Technology 5 microns/year
  • 8. 682 Sulaiman et al., Biosci., Biotech. Res. Asia, Vol. 7(2), 675-688 (2010) Besides that, it is important that the correct will require a profile with a greater peak to troughblast profile is achieved before the substrate is measurement than a thin coating.coated. Paint manufacturers should specify the blastprofile for each coating, in terms of the pattern Blast cleaning standardrequired for that paint. The instrument to measure The most commonly referred standardsthe blast profile is called “Blast Profile gauge” and are Steel Structure Painting Council (SSPC),the reading is in micron. In general, thicker coatings National Association of Corrosion Engineers Existing flow chart for ship paint application
  • 9. Sulaiman et al., Biosci., Biotech. Res. Asia, Vol. 7(2), 675-688 (2010) 683(NACE) and Swedish Standards or International high, an inadequate coating coverage will resultStandards Organization (ISO) (1988). Each over any high and sharp peaks and this could leadstandard is divided into four standards of to premature coating breakdown. However, gritcleanliness, broadly described as; brush off, blasting can also result in an insufficient surfacecommercial, near white metal and white metal. profile and may simply re-distribute contaminationWhilst each standard may be differ slightly in over the steel surface trapping contaminants underrequirements and ter minology. The Table 5 the surface.indicates the grades for steel surfaces using blastcleaning. Paint Application The paint application is to provide a filmBlast profile which give protection or decoration of ship hull The correct blast profile is very important being painted. The success of any application andprior to painting. If the blast profile is produced too subsequent performance depends on some Improved flow chart for ship paint application
  • 10. 684 Sulaiman et al., Biosci., Biotech. Res. Asia, Vol. 7(2), 675-688 (2010) Fig. 1: Hull quadrants (IRTA, 2009) Fig. 2: Flow chart of salt test measurement by “Bresle kit sample”
  • 11. Sulaiman et al., Biosci., Biotech. Res. Asia, Vol. 7(2), 675-688 (2010) 685variables such as surface preparation, film Method of paint applicationthickness of the paint system, methods of Airless spray is now almost a universalapplication and conditions during application. method for ship side paint application. This is by far the most important and efficient method for theFilm thickness measurement application of heavy-duty marine coatings, which The wet film thickness (WFT) of the coating allows the rapid application of large volumes of paintis measured and can be converted to a dry film as well as the application of high build coatingsthickness (DFT) following the paint maker’s without thinning. Airless spray method can reduceguidelines for that product. The wet film thickness the overspray and bounce back problems. Moreover,measurement can be determined by how much it follows that ships paints must be formulated andcoating should be applied to reach the specified manufactured to be suitable for application by airlessDFT. The dry film or wet film ratio is based on spraying.percentage of solids by volume of the coating beingused. The basic formula to measure the WFT is: Airless spray is a technique of spray application which does not rely on the mixing of paint with air to provide atomization. Atomization is achieved by forcing the paint through a special and precise constructed nozzle or ‘tip’ by hydraulicShip side coating thickness range pressure. The choice of tip determines the film Different ship side area has different Dry thickness applied per pass of the spray gun andFilm Thickness (DFT). Table 6 shows ship side should be selected in accordance with the coatingcoating thickness range. manufacturer’s guidelines. The speed of each pass Fig. 3: Flow chart of blast profile measurement by testex profile tape
  • 12. 686 Sulaiman et al., Biosci., Biotech. Res. Asia, Vol. 7(2), 675-688 (2010)and volume solids of the paint will influence film Toxic antifouling means that prevention of foulingthickness. Airless spray equipment normally by a surface coating requires the maintenance, inoperates at fluid line pressure up to 5000 psi (352 the water in contact with the coating, of akg/cm2) and care should be taken periodically. concentration of toxin that is lethal to all of the target organisms. Meanwhile foul release coating has a Modern products are most commonly surface with very low surface energy which reducesapplied by airless spray. One airless spray gun is the efficiency of the attachment processcapable of spraying between 50 and 80 litres dramatically, i.e. a “non-stick” surface is presentedof paint per hour, i.e. covering 150 – 400 m 2/hr to the organism.at the required film thickness. Moreover, airlessspray application produces less overspray than Typical ship paints propertiesconventional air-assisted spraying, but there is Ship paints properties are very importantsome risk of painters inhaling spray droplets. for us to understand because this is important onAntifouling compositions offer special problems choosing the correct and proper types of ship paints.because of the poisons they contain, this The Table 7 shows the properties of the ship hullapplies both to the older copper poison types painting systems most commonly used in theand more particularly to the organometallic marine industry.poisons. Thus, suitable protective equipment mustbe used. Coating compatibility Coating compatibility is important when the Commonly, painting must be inspected maintenance or repair work is carried out, to ensureregularly to ensure that specifications regarding that the repair coat will adhere to the original paint,surface preparation, wet and dry film thickness, otherwise failures will occur between the individualdrying times, mixing of two-pack materials, layers (inter-coat adhesion failure). Incompatibilityovercoating intervals, quality of workmanship and between coating types, such as epoxy anticorrosiveothers are met. coatings with some types of antifouling paints, can be overcomed by the use of a tie coat, which hasCondition during application good adhesion to both paint types and is therefore There are some factors which must be applied onto the anti-corrosive layer before theconsidered during paints application. The major antifouling layer is applied. Thus, paint compatibilityfactors are condition of substrate, temperature, is a factor which must be takes as consideration.relative humidity, weather conditions andcondensation. Performance of antifouling paints determined by hull roughness The proper ambient temperature for steel Ship’s underwater hull is painted to protecthull painting process should be 3°C above dew point. the substrate and also prevent undue roughness.Most paints can tolerate high humidity but The most significant cause of hull roughness iscondensation must not form on the surface being fouling. Normally, paint fouling control technologypainted. During the painting process for the ship can be characterized into 4 types: Controlledhull, the relative humidity must below 85%. Depletion Polymer (CDP), TBT Free Self PolishingFurthermore, paint should not be applied during fog, Copolymer (SPC), Hybrid TBT Free Self Polishingmist or raining. Generally, under these conditions, Technology and Foul Release Technology. Each typeit is difficult to maintain the steel temperature above of paint fouling control technology has differentthe dew point. Besides that, condensation is Average Hull Roughness (AHR) value. Table 8forbidden during hull painting process. shows the AHR value for these 4 types of AF paints.Antifouling Paints for the Ship Hull Area The paint fouling control which has Generally, there are two basic mechanisms smallest AHR value has lower percentage increaseemployed in coatings to prevent fouling settlement in power needed or fuel used. Thus, foul releasewhich are toxic antifouling and foul release coating. technology can save more power and fuel used.
  • 13. Sulaiman et al., Biosci., Biotech. Res. Asia, Vol. 7(2), 675-688 (2010) 687Antifouling Systems Regulations and Convention include Yard’s Painting executive, Shipowner’s Generally, antifouling system has their representative, suppliers, Paint Manufacturer andregulation to control the harmful antifouling systems Surveyors. The responsibility of Yard’s Paintingon ships. This is very important for us to understand executive is to use checklists and inspection recordsin order to enable the ship become compliant. In to ensure the standards are followed. Besides that,this research, I include Antifouling System (AFS) they will conduct audit by QA department on arequirement and the Convention and Best monthly basis. If t sign of any incompliance is found,Management Practices on marine pollution by yard person such as Project Manager will issueremoval of antifouling coatings from ships. From the Quality Assurance Note (QAN) or NonAFS requirement, there is a prohibition on the Conformance Report (NCR) towards suppliers. QANapplication or re-application of organotin is only for light or small incompliant, but NCR is forcompounds which acts as biocides in antifouling heavy incompliant.systems. When existing vessels replaced theantifouling after 1 January 2003, they complied with Fur thermore, Paint Manufacturer’sthis requirement or provided sealer to avoid a non- inspector must have a widely experience and goodcompliant antifouling to avoid leaching. All vessels judgement in order to make sure the paint job wasafter 1 January 2008 shall either not bear such completed as specified. They need to take concerncompounds on their hulls or external parts or on many aspects throughout the painting process.surfaces; or apply coating that forms a barrier Adhesion test or “dolly test” which is commonly(sealers) to such compounds such as leaching from known among the paint inspectors, would have tothe underlying non-compliant antifouling systems. be carried out when the external hull of the ship is being grit blasted and applied fresh coatings. This Fur thermore, Convention and Best is to ensure the paint adhesion onto the substrateManagement Practices is to prevent marine pollution hull can withstand a pull-out pressure of not lessby the removal of ship antifouling coatings. Thus, than 300 psi. The higher the pressure of the “pull-management for AFS waste collection is very out” test, the stronger the adhesion of the paint ontoimportant throughout the process. The adoption of the steel substrate is. All parties must take concernmanagement practices for the application and on their responsibilities to ensure the qualityremoval of antifouling systems can reduce of obtained is in compliance. Every daily log, testsbiocides into the natural environment. The aspects and inspections work must be recorded for futureinclude choice of antifouling system, and collection, evaluations of the painting. There is no any by-passtreatment, and disposal of spent coatings which steps that can be skipped. Throughout the processhave an impact on the release of biocides into the above, the quality of the paint is assured.environment. If not managed properly, it may resultin high concentrations of biocides in the marine CONCLUSIONsediments in areas close to where application andremoval activities are conducted. Conclusion and recommendation Fouling is unwanted accumulation materialQuality Assurance on solid surface. There is either living organism Each model has their own standards in (biofouling) or non living substance. Antifoulingorder to make sure the standard is controlled and paints are used to prevent the biofouling. There arecomplied with the rules and requirements. To ensure two types of antifouling paints which are toxic andthe model is controlled efficiently, quality assurance non-toxic alternatives to TBT systems. Nowadays,plays an important role. The purpose of a quality there is a trend to use the foul release technologyassurance system is to prevent problems from which is also known as non-toxic alternatives tooccurring, detect them when they do, identify the TBT systems such as silicon-type foul release AFcause, remedy the cause and prevent recurrence. paint. This product is expensive and requires longerQuality Assurance mechanism in this model is to working period to accomplish but the long termensure that accuracy and precision throughout a benefits can be seen from the smooth and fasterprocedure. The parties involved in this procedure speed of the vessel reaching its destination and it’s
  • 14. 688 Sulaiman et al., Biosci., Biotech. Res. Asia, Vol. 7(2), 675-688 (2010)cost effective saving which is believed to be about assurance that a paint job was completed as40%. According to LNG Carrier Owners’ Manual, specified. There are many failure cases due to poorfoul release coatings are proving themselves to be workmanship occurred after the work has beenthe ideal solution for LNG hull and propeller fouling completed and has been paid for. Beside that,control. Not only can they keep hulls and propellers quality assurance is part of quality managementsmooth and free of macro-fouling for extended focusing on increasing the ability to fulfillservice period of up to 60 months, but in addition, requirements of the process. As a conclusion, thesince they do not use biocides to control fouling, model results are complied with the standardthey can be an integral par t of an LNG requirements.environmental management plan. Recommendation Furthermore, ship paint application is the There are many aspects in this researchmost important part to control the performance or which could be investigated in the future. Somequality of antifouling paints. High performance paint suggestion and recommendations on future studysystems are especially sensitive to misapplication are as follow:and knowledge of the application characteristics and i. The practical way to measure hull fouling isrecommended film thickness is vital to obtain to use a professional diver to not onlyoptimum results. For optimum service life, the measure but to survey or inspect the generalsurface must be completely free of all contaminants condition of the hull as a whole and recordthat might impair performance and should be treated with video camera or CCTV. This is becauseas such to assure good and permanent adhesion hull fouling varies along the hull.of the paint system. The quality of surface ii. There are many ship paints applicationpreparation has a direct relation with the lifetime of methods discussed in this paper Therefore,a system. Nowadays, the paint application method it is suggested that investigation for eachcommonly used airless spray. The degree of skill of methods in much more details.the personnel can affect the performance of paints. iii. The performance of AF paints can beBesides that, paints materials, coating compatibility determined by many factors. Thus, it isand environmental conditions also need to be suggested that investigation for performanceconcidered. Different paints materials have different or quality of AF paints to be done in muchproperties, thus have different effects on the paints more detail.performance. AKNOWLDGEMENTS Throughout the whole ship paintingprocess, it is necessary to inspect the work as it The author greatly aknowledge, Chin Meiprogresses if there is to be any reasonable Sam for direct contribution in this study. REFERENCES1. Edyvean, R.G.J., Fouling and Corrosion by 4. Kan, S., Shiba, H., Tsuchida, K. and Yokoo, Microalgae, PhD Thesis, University of K., Effect of fouling of a ship’s hull and Newcastle-upon-Tyne, Newcastle-upon- propeller upon propulsive performance. Tyne (1982). International Shipbuilding Progress, 5: 15-2. IMO., Antifouling Systems. International 34 (1958). Convention on the Control of Harmful Anti- 5. Mosaad, M.A., Marine Propeller Roughness fouling Systems on Ships. International Penalties, PHD Thesis. Department of Marine Maritime Organization. London (2005). Technology. University of Newcastle-upon-3. IRTA., Safer Alter natives to Copper Tyne (1986). Antifouling Paints. San Diego (2009).