Browsing by Author "Joshi, Madhu"

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Analysis of antifouling paints using drum test apparatus
(RINA, 2015-12) Joshi, Madhu; Mukherjee, A.; Misra, S. C.; Ramesh, U. S.
Ship has been recognized as a major factor in introduction of non-native and harmful organisms which causes deleterious effects on the performance of the vessel. More than 70% of Invasive species worldwide have found to be due to hull fouling. To mitigate fouling, underwater parts of the vessels are coated with antifouling paints. Antifouling paints provide foul-free hulls up to a maximum of 95 % of the vessels underwater area. There are a number of types of these paints but “self-polishing coatings” are predominantly preferred by the shipping industry. In these types of coatings, a thin layer of biocide containing paint (typically 2 to 5 microns/month) is leached or “polished” away. This polishing action primarily depends on the hydrodynamic surface forces on the vessels hull. The higher the fluid velocity, the higher are the polishing rate. Certain areas of the vessel such as near the bow, stern, etc experience higher fluid velocity and therefore higher polishing rates thereby resulting in premature fouling. Conversely, areas where the flow rates are considerably smaller would experience lesser polishing rates which would result in insufficient amount of biocides being delivered which would again result in premature fouling. In order to study and estimate the polishing rates of Anti Fouling paint we have designed, fabricated a rotating drum test facility .Wall shear stress are to be calculated by CFD methods
Anifouling paint schemes to minimize the risk of transmigration of invasive species
(Sixteenth National Congress on Corrosion Control, 2012-08) Mukherjee, A.; Joshi, Madhu; Misra, S. C.; Ramesh, U. S.
Biocorrosion or biofouling on ships hull occurs to the attachment of barnacles, mollusks and Other aquatic organisms on the surface of ships which leads to increase in fuel consumption, reduction of the vessels speed, premature failure of the hull, etc. Recent developments in antifouling paints, in general, prevent fouling in about 95% percent of the vessels underwater surface, which ship operators find satisfactory as far as the routine vessel operation is concerned. However, this is not sufficient enough to prevent the transport or invasion of alien species which result in numerous environmental issues that include reduction and extinction of native species and thereby seriously disrupting the natural ecosystems. Virtually all ocean going vessels are coated with antifouling paints, predominant among them are “Self polishing coatings” and “Foul Release Coatings”. Both these coatings depend on hull shear forces caused by the motion of the vessel, by different mechanisms, to result in the hull to be essentially foul-free. Currently hulls are coated with a uniform layer of antifouling paints. However, CFD analysis conducted on various types of vessels have shown highly non-uniform wall stress distribution along the vessels hull. This results in premature paint failure for “Self polishing Coatings” and insufficient shear forces for “Foul release coatings” to release the attached fouling organisms. Both these factors contribute significantly to the transmigration of invasive species. Preliminary results of the current work indicate that certain areas of the vessel such as such as bow thrusters, sea chest, stern tube, rudder etc. are the likely areas to be heavily fouled thereby warranting special attention in such areas. Solutions to these issues include alternative paint schemes/formulations in the identified niche areas to account for non-uniform shear and polishing of paints. Such schemes would ultimately reduce the risk of transmigration of invasive species
Antifouling paint schemes for green SHIPS
(Elsevier, 2019-01-09) Joshi, Madhu ; Misra, S. C.; Ramesh, U. S.
Recent advances in antifouling (AF) paints in general prevent fouling in about 95% of the vessel's immersed surface. However the remaining area which amounts to 5% or less of the total area does get fouled. Although this level of fouling has marginal impact on the routine performance of the vessel it is a predominant vector for the transmigration of invasive species which is now a serious environmental concern. Virtually all ocean going vessels are coated with antifouling paints predominant among them are “Self polishing coatings”. CFD analysis conducted on various types of vessels have indicated that there are certain “hotspots” where the polishing rates are exceedingly high and would polish the AF paints at a much faster rate and ultimately result in the failure of the AF coating. A possible solution to this issue is to first identify these hotspots and suitable paint schemes/formulations are to be applied in such areas. An experimental procedure utilizing a “drum-test” apparatus can be used to compute the coating thicknesses based on wall shear stresses. Such painting schemes would prevent the premature failure of the AF coating in general and significantly reduce the risk of transmigration of invasive species in particular.
Characterisation and performance of environment friendly natural antifoulants
(Indian Maritime University, Chennai, 2017) Joshi, Madhu; Misra, S. C.; Mukherjee, Adithiya; Sivakholundu, K. M.
In the middle of the 19th century antifouling paints were developed to prevent marine growth on ship hulls. Due to fouling, there is an increase in fuel consumption, reduction in vessel speed, increase in greenhouse emissions, acceleration of corrosion and propagation of invasive species. Today, ships are required to be drydocked every 5 years when the bottom hull is cleaned of fouling growth and painted with fresh coats of antifouling paint. Hull fouling takes place in marine environment in varying degrees. Density of marine organisms is higher in coastal water and since run-off from the land brings a wealth of food on which plankton exists, boats moored in harbours and estuaries are heavily fouled as paint depletion is low. There is an ongoing effort to improve the antifouling paint quality which can reduce fouling growth on hull surface and increase the gap in dry-docking schedules. But with this effort towards improving paint quality, it has been observed that paint components can be toxic causing ecological harm to ocean environment. Hence extensive research is being done in Natural Product Antifoulants (NPA). Natural product derivatives such as marine organisms like corals, sponges and seaweeds protect their body surfaces with several biochemical substances. Similarly, a wide array of terrestrial plants possess several natural compounds such as terpenes, acetylenes, polycyclic compounds, steroids, phenols, isothiocyanates, nitrogen containing compounds, glycerol derivatives, higher fatty acids and enzymes that are perhaps suitable as antifouling agents. Due to their availability and physio-chemical properties, Pongamia pinnata (Karanj) seed oil and Azadirachta indica (Neem) seed oil have been studied in the work for their potential use as antifouling agents. The bioassay studies against barnacle larvae reveal that Azadirachtin (Neem bioactive) has acute toxicity against barnacle larvae, percent motility inhibition being 64.78+3.95 at 0.5 µg.ml-1, 81.24+8.23 at 1.0 µg.ml-1and 100 at 5.0 µg.ml-1 in 24 hrs. Karanjin (Karanj bioactive) which also showed positive results against barnacle larvae at higher concentration, percent motility inhibition being 29.2+5.4 at 20 µg.ml-1 , 57.3+23.9 at 50 µg.ml-1and 85+25.9 at 100 µg.ml-1 in 4 hrs. The results of Neem toxicity also agrees with what was previously reported about Neem oil toxicity against L. Fortunei (Pereyra et.al., 2011) and Karanj oil has been used indigenously with Chandrus (a plant resin from members of the family Dipterocarpaceae) and lime in wooden boats to protect against termites Santhakumaran et.al., 1982). Marine exposure trials were conducted to find out the efficacy of Neem oil and Karanj oil in marine environment and these investigations on biocidal antifouling compositions were carried out at two sites at Visakhapatnam harbour. Environmental parameters such as temperature, salinity, pH and dissolved oxygen were monitored at the two stations. The seasonal pattern didn’t vary much during the field trials. The analyses of variances followed by post hoc tests of biofoulers recruitment both in terms of their numerical abundance and quantitative spread over the metal test plates from different points of view clearly demonstrated the usefulness of treatments in controlling biofouling formations at two sites at Visakhapatnam harbour despite spatial and temporal variations in the quality and quantity of biofouling on planted coupons. Analysis of variance conducted on the recruitment of Amphibalanus amphitrite amphitrite during various months as well as treatments at Visakhapatnam Fishing Harbour divulgedno significant difference in the abundance of this fouling barnacle species among various months (p=0.06), but projected very highly significant difference among various treatments given to the test plates (p = 4.78x10-8) signifying the effect of treatments over controls in curtailing the balanid recruitment. Thus, the overall assessment of performance of the bioactives of Karanj and Neem during the field exposure at the two sites in Visakhapatnam harbour in the backdrop of the performance of the Controls and Commercial antifoulant reveals that Neem bioactive is arginally better than Karanj bioactive and formulations incorporating still higher doses than the ones employed during the present investigation are required to achieve desired outcome of total prevention of biofouling on metal surfaces. Also, in order to significantly minimize fouling, antifouling (AF) painting schemes must also take into account the uneven hydrodynamic forces at the water-hull interface. If a correlation between wall shear stress at all locations on the vessels hull with rate of antifouling paint depletion is known, then the appropriate AF scheme could be applied. To obtain such a correlation the “Drum-Test” apparatus was devised, designed, manufactured and utilized. The results of paint film depletion of three self-polishing copolymer (SPC) antifouling paints versus time for various speeds of the drum indicated that Paint 3which was TBT free SPC antifouling paint with Cuprous oxide and organic biocides as active ingredients had maximum polishing rates while in Paint 1 which was TBT free SPC antifouling paint based on Copper acrylate, the polishing action was minimum. This implies that that Paint 1 could be coated for high speed high activity vessels such as ocean going vessels while Paint 3 would be an option for low speed low activity vessels such as harbour crafts, motor launch etc. This is expected to help in reducing the proportion of antifoulant in the proposed formulations paving way both for the development of eco-benign and cost-effective antifouling formulations. Key words: fouling, paint depletion, Natural product antifoulants, marine, terrestrial, bioactives, Commercial antifoulants, antifouling (AF) painting schemes, wall shear stress, Drum test apparatus, Selfpolishing Copolymer (SPC).
Control of biocorrosion to prevent the propagation of invasive species
(Indian Maritime University, Chennai, 2010-09) Joshi, Madhu; Mukherjee, A.; Ramesh, U. S.; Misra, S. C.
Biocorrosion or biofouling on ships hull occursdue to the attachment of barnacles, mollusks and other aquatic organisms on the surface of ships which leads to increase in fuel consumption, reduction of the vessels speed, premature failure of the hull, etc. Recent developments in antifouling paints, in general, prevent fouling in about 95% percent of the vessels underwater surface, which ship operators find satisfactory as far as the routine vessel operation is concerned. However, this is not sufficient to prevent the transport or invasion of alien species. In recent years the issue of invasive marine species has been receiving considerable attention due to the fact that introduction of nonidegenous species or non-native species transmigrated from other areas to coastal waters often results in the reduction and even extinction of the native species and thereby severely disrupting the natural marine ecosystems. The predominant vector for the transport of nonindigenous species in marine environments has been shipping. While ballast water receives the most attention, hull fouling is now considered to be the most significant means for translocation of these organisms. For example, 90 percent of the 343 marine alien species in Hawaii are thought to have arrived through hull fouling Certain niche areas of the vessel such as bow thrusters, sea chest, stern tube, rudder etc. are the likely areas to be heavily fouled. In addition, the other areas that are likely to be fouled are on locations where antifouling paint has been worn of due to excessive shear and bending of the hull. This paper reviews the various antifouling strategies and aims identify areas on the hull surfaces of certain classes of vessels that are prone to fouling by excessive shear and bending and identify suitable antifouling treatments to further reduce the risk of transportation of alien species.
Control of biocorrosion to prevent the propagation of invasive species
(Indian Maritime University, Chennai, 2010-09) Joshi, Madhu; Mukherjee, A.; Ramesh, U. S.; Misra, S. C.
Biocorrosion or biofouling on ships hull occursdue to the attachment of barnacles, mollusks and other aquatic organisms on the surface of ships which leads to increase in fuel consumption, reduction of the vessels speed, premature failure of the hull, etc. Recent developments in antifouling paints, in general, prevent fouling in about 95% percent of the vessels underwater surface, which ship operators find satisfactory as far as the routine vessel operation is concerned. However, this is not sufficient to prevent the transport or invasion of alien species. In recent years the issue of invasive marine species has been receiving considerable attention due to the fact that introduction of nonidegenous species or non-native species transmigrated from other areas to coastal waters often results in the reduction and even extinction of the native species and thereby severely disrupting the natural marine ecosystems. The predominant vector for the transport of nonindigenous species in marine environments has been shipping. While ballast water receives the most attention, hull fouling is now considered to be the most significant means for translocation of these organisms. For example, 90 percent of the 343 marine alien species in Hawaii are thought to have arrived through hull fouling Certain niche areas of the vessel such as bow thrusters, sea chest, stern tube, rudder etc. are the likely areas to be heavily fouled. In addition, the other areas that are likely to be fouled are on locations where antifouling paint has been worn of due to excessive shear and bending of the hull. This paper reviews the various antifouling strategies and aims identify areas on the hull surfaces of certain classes of vessels that are prone to fouling by excessive shear and bending and identify suitable antifouling treatments to further reduce the risk of transportation of alien species.
Environmentally friendly antifouling paints and painting schemes
(International Journal of Innovation Research & Development, 2012-12) Joshi, Madhu; Mukherjee, A.; Misra, S. C.; Ramesh, U. S.
Since the 1970's Tributyl tin based antifouling paints were widely used to control fouling on ships hulls. These coatings offered up to 5 years of foul-free hulls and were the most effective antifouling paints ever produced. However, due to serious environmental effects, these paints have been banned since 2008 and have been replaced by copper based antifouling paints with some success. However, the extensive use of copper based antifouling paints has led to the accumulation of cooper and its compounds in the marine environment particularly in the vicinity of ports and harbors and is beginning to pose a serious environmental problem. This paper explores the possibility of incorporating environmentally friendly biocides in antifouling paints that exhibit a low persistence in the marine environment particularly those biocides that are available in the Indian context. Another serious problem facing the marine environment is the issue of Invasive species. In recent years the issue of invasive marine species has been receiving considerable attention due to the fact that introduction of non indegenous species or non-native species transmigrated from other areas to coastal waters often results in the reduction and even extinction of the native species and thereby severely disrupts the natural marine ecosystems. The predominant vector for the transport of nonindigenous species in marine environments has been shipping. While ballast water receives the most attention, hull fouling is now considered to be the most significant means for translocation of these organisms. Certain niche areas of the vessel such as bow thrusters, sea chest, stern tube, rudder etc. are the likely areas to be heavily fouled. Although this fouling does not affect the overall performance of the vessel, would however, be a vector for the transportation of Invasive species. In addition, the other areas that are likely to be fouled are on locations where antifouling paint has been worn of due to excessive shear and bending of the hull. This paper attempts to identify such areas using CFD simulations and suggest that special paint schemes must be incorporated in these niche areas.
Failure analysis of antifouling paints on ships hull
(NISCAIR-CSIR, India, 2014-11) Joshi, Madhu; Mukherjee, A.; Misra, S. C.; Ramesh, U. S.
Fouling on ships hull occurs due to the attachment of barnacles, mollusks and other aquatic organisms on the underwater area of the hull. This leads to increased drag, fuel consumption, resulting in unscheduled dry-docking. Recent advances in antifouling (AF) paints, in general, offer protection against fouling in about 95 % of the vessels immersed surface. However, the remaining area which amounts to 5% or less of the total area does get fouled. Although this level of fouling has marginal impact on the routine performance of the vessel, it is a predominant vector for the transmigration of invasive species which is a serious environmental concern. Virtually all ocean going vessels are coated with antifouling paints, predominant among them are “Self polishing coatings”. These coatings depend on the shear forces on the hull surface caused by the motion of the vessel for the paint to “polish” away and release a biocide at a predetermined rate that results in the hull to be essentially fouling free. Currently hulls are coated with a uniform layer of antifouling paints. However, computational fluid dynamics (CFD) analysis conducted on various types of vessels have indicated that there are certain “hotspots” where shear stresses and therefore the polishing rates are exceedingly high which would polish the AF paints at a much faster rate and ultimately result in the failure of the AF coating. The analysis also indicates that these hotspots primarily depend on the profile of the vessels, its speed and its draft. The current practice of a uniform coat of AF paint does not take into account the fact that there are certain areas of the vessel where the polishing rates are excessive. A possible solution to this issue is to first identify these hotspots and suitable paint schemes/formulations are to be applied in these areas. Such painting schemes would prevent the premature failure of the AF coating in general and significantly reduce the risk of transmigration of invasive species.
Natural biocides in antifouling paints
(International Conference on Ship and Offshore Technology : Technological Innovations in Ship Building, 2013-12) Joshi, Madhu; Mukherjee, A.; Misra, S. C.; Ramesh, U. S.
Since the 1970’s Tributy tin based antifouling (AF) paints were widely used to control fouling on ships hulls. These coatings offered up to 5 years of foul-free hulls and were the most effective antifouling paints ever produced. However, due to serious environmental effects, these paints have been banned since 2008 and have been replaced by copper based antifouling paints with some success. However, the extensive use of copper based antifouling paints has led to the accumulation of copper and its compounds in the marine environment particularly in the vicinity of ports and harbors and is beginning to pose a serious environmental problem. Restrictions on the use of copper based AF paints have been initiated by many western countries and it is expected that these restrictions would only grow in the years to come. In addition, these coatings are usually incorporated with “booster biocides” such as Diuron, Irgarol, Seanine, etc to improve their efficacy. The booster biocides also significantly contribute to the existing environmental concerns. The search is therefore on for a “benign AF product” that affects target organisms only and exhibits low persistence in the aquatic environment. A few natural produces fill in to these requirements. In the Indian context, Neem and Karanjin exhibit biocidal properties which could be tapped as effective AF agents. This paper reviews the various natural products that show promise as AF agents and explores the possibility of incorporating these products in AF paint formulation.
Need of natural biocides in antifouling paints for prevention of marine pollution
(International Journal of Innovation Research & Development, 2015-07) Joshi, Madhu; Mukherjee, A.; Misra, S. C.; Ramesh, U. S.
"Antifouling paints were developed to prevent marine growth on ship hulls in the middle of the 19th century. As they were designed to continuously leach biocides at the paint/seawater interface which were the predominant means of controlling fouling for a vast majority of the vessels, over a period of years in the latter part of the last century there has been a marked improvement in the effective life of antifouling paints. Different types of antifouling paints came into being but after a particular breakthrough when self- polishing paints were developed in 1960s. Due to its controlled leaching rate, the self -polishing paints containing TBT was a huge success. However, due to serious environmental effects, these paints have been banned since 2008 and have been replaced by copper based antifouling paints with some success. It was observed that the extensive use of copper based antifouling paints has led to the accumulation of copper and its compounds in the marine environment particularly in the vicinity of ports and harbors and is beginning to pose a serious environmental problem. Foul release coatings are biocide-free –works on a foul release basis by providing a very smooth, low-friction surface which reduce the strength of adhesion of fouling. However, they are applicable only to high- speed, high-activity vessels, in addition to other issues such as high cost, difficult, application procedure and are easily prone to mechanical damage. Biocides from natural products appear to be the only viable alternative in the foreseeable future to protect ship hulls from fouling. This paper reviews the possible natural products that have the potential to be incorporated in to commercial antifouling paints and explores their range of activity"