Ballast Tanks
The lifetime of a ship is greatly influenced
by the corrosion conditions, particularly in the ballast tanks. To fulfil the
demand for a long service life, the vessel should ideally be protected with a
high-quality system already at the newbuilding stage. After delivery of the vessel a regular inspection and maintenance plan should be established where any damage, when discovered, is touched up with a suitable coating. In this way it will be possible to avoid major problems almost indefinitely.
The correct and optimum ballast tank coating system is tailormade to the specific type of vessel and its operating parameters: cargo temperature (min. and max.), trading pattern, maintenance schedule, expected service life - and also to the initial investment.
Consequently, to fulfil all requirements, Hempel offers different products and systems. Please contact your local Hempel representative for advice on optimum specifications and repair options.
The ballast tanks represent more than 50% of the entire coated area per vessel, and as large parts of the ballast tank areas are inaccessible during service, the quality of surface preparation and application is of crucial importance.
Throughout a ballast tank coating job, Hempel's coating advisers will assist in planning, offer useful and relevant advice and take care of job monitoring and quality control. They are in effect the customer's assurance that Hempel's quality ballast tank coatings are applied so as to offer the best protection and provide the most cost-effective performance.
The Committee discussed the use of toxic antifouling paints and the need for an instrument to regulate their use. Antifouling paints are used to coat the bottoms of ships to prevent sealife such as algae and molluscs attaching themselves to the hull - thereby slowing down the ship and increasing fuel consumption.
Most antifouling paints contain metallic compounds which slowly "leach" into the sea water, killing barnacles and other marine life that have attached to the ship - but studies have shown that these compounds persist in the water, killing sealife, harming the environment and possibly entering the food chain. One of the most effective antifouling paints, developed in the 1960s, contains tributyl tin (TBT), which has been proven to cause deformations in oysters and sex changes in whelks.
The Committee adopted a Resolution in 1990 which recommended that Governments adopt measures to eliminate the use of antifouling paint containing TBT on non-aluminium hulled vessels of less than 25 metres in length and eliminate the use of antifouling paints with a leaching rate of more than 4 microgrammes of TBT per day. Some countries, such as Japan, have already banned the use of TBT in antifouling paint for most ships.
A Correspondence Group set up by IMO, involving nine Member Governments, one Associate Member, and four non-governmental organizations, has been looking at how to reduce further the harmful effects on the environment of TBT antifouling paint. The use of TBT could be restricted or banned.
The Committee agreed that the Correspondence Group should continue its work with a final report to be submitted to the next session in March 1998
Committee tackles ballast water problem
The Committee discussed measures to deal with the problem of harmful aquatic organisms transported in ballast water and approved a draft Assembly Resolution on Guidelines for the Control and Management of Ship's Ballast Water to Minimize the Transfer of Harmful Aquatic Organisms and Pathogens, for submission to the 20th Assembly for adoption.
There has been increased awareness in recent years of the environmental damage caused by the introduction of unwanted aquatic organisms in ballast water, used to stabilize vessels at sea. Examples of introductions of non-indigenous organisms in new locations include the introduction of the European zebra mussel (Dreissena polymorpha) in the North American Great Lakes, resulting in expenses of billions of dollars for pollution control and cleaning of fouled underwater structures and waterpipes; and the introduction of the American comb jelly (Mnemiopsis leidyi) to the Black and Azov Seas, causing the near extinction of the anchovy and sprat fisheries.
Human health has also been badly affected, with the transportation of the bacterium vibrio cholerae (cholera) to Latin American coastal water, probably through discharges of ballast water from Asia, and the introduction of the South-East Asian dinoflagellates of the genera Gymnodinium and Alexandrium, which cause paralytic shellfish poisoning, to Australian waters.
The draft guidelines, which have been drawn up by a working group on ballast water, are aimed at minimizing the risks of introducing harmful aquatic organisms and pathogens while maintaining ship safety. Some States have already introduced mandatory management of ballast water to prevent the introduction of exotic species.
Guidelines for Preventing the Introduction of Unwanted Organisms and Pathogens from Ships' Ballast Waters and Sediment Discharges were adopted by the Committee in 1991 and subsequently as an Assembly Resolution A.774(18), but the revised version incorporates further recommendations on tackling the problem, including how to lessen the chances of taking on board harmful organisms along with ballast water.
The recommendations include informing local agents and/or ships of areas and situations where uptake of ballast water should be minimized, such as areas with known populations of harmful pathogens or areas near to sewage outlets. Ships should operate precautionary practices, through avoiding loading ballast water in very shallow water or in areas where propellers may stir up sediment. Unnecessary discharge of ballast water should also be avoided.
Procedures for dealing with ballast water include exchange of ballast water at sea and discharge to reception facilities, while the Guidelines note that in the future treatment using heat or ultraviolet light could become acceptable to port States.
IMO's Maritime Safety Committee (MSC) and the Committee have already approved guidance on safety aspects relating to the exchange of ballast water at sea, which outlines procedures for exchanging ballast water and point out safety issues which need to be considered, such as avoidance of over and under pressurization of ballast tanks and the need to be aware of weather conditions.
The Committee approved a programme of work for the ballast water working group, which includes developing draft Regulations on ballast water management to be adopted as an Annex to MARPOL at a Conference of Parties to the International Convention for the Prevention of Pollution from Ships, 1973, as modified by the Protocol of 1978 (MARPOL 73/78), the main international convention dealing with the prevention of pollution from ships. The Conference is scheduled to be held in the year 2000.
No comments:
Post a Comment