NEWS ANALYSIS
The following are proposals from the co-sponsors for strengthening the “Guidelines (G8)”
“Coatings; Resolution MSC.215(82) provides details on the Performance Standard for Protec- tive Coatings (PSPC). While proposals for standard tests on the impacts of BWMS on corrosion and coatings have been put forward by GESAMP-BWWG, the current corrosion and coating impact tests undertaken by BWMS manufacturers frequently fall well short of the standards established in the PSPC. This is of concern for particular types of
BWTS. For example, coating industry specialists have observed that in situations where oxidising species are used in the BWTS there is an increased risk of corrosion within the ballast water tank and piping system. Other observations have been made with regard to the impact on epoxy coatings from the Active Substances used in the BWTS. Tests undertaken thus far have been limited in their scope. This limitation includes the doses that the coatings are subjected to, i.e. it does not take into account the probability of increases in doses due to more nutrient rich conditions, user error or dosage equipment failure. Another limitation is that of the time periods that the coatings are subjected to. Some coatings have only been subjected to the Active Substance doses over short (6 to 8 weeks) periods as opposed to a more thorough period of more than six months. The coating industry representatives, IPPIC, in
their submission MEPC 63/INF.9 also commented that the BWTS manufacturers should perform appropriate testing during the development phase of their equipment. IPPIC points out that the MEPC has only given general guidelines to the BWTS manufacturers for compatibility tests with coatings. The co-sponsors fully concur with IPPIC's view that, in order to give more clarity on potential effects, it is imperative that test protocols are standardised, described and thoroughly verified. Filters; As a pre-treatment measure some
BWTS use filters to remove larger organisms and particles. Some of the key challenges presented by the use of filters include but are not limited to: Suboptimal operation at either end of
the
pressure range. Some Type Approval Certifi- cates specify a minimum and maximum pressure. This indicates that at certain pressures the filters may not operate effectively. This is especially so at low pressures, such as during the last period of de-ballasting (tank stripping) when minimal volumes of ballast water will be pumped through
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the BWTS or simply when topping up the ballast tanks. Back flush times may be extended in high
sediment ballast uptake areas. This will result in increased back flushing being required and a consequential decrease in the capacity of the system overall. Such a variation in sediment or particle loading is rarely assessed during the type approval stage and as such actual treatment volumes in real-life situations may be greatly reduced. This will result in delaying vessels at certain ports with high sediment waters. The physical nature of certain organisms also
presents problems for filters. In areas of rich phytoplankton experience shows that plankton grasses can easily disrupt and quickly limit the flow of water through filters. Such limitations are difficult to overcome as the backflushing is not always effective in removing the flora in their entirety, unlike say sediment or mud which is particulate in nature. The co-sponsors would propose that any
review of the "Guidelines (G8)" assesses the need to ensure that the BWTS which rely on filters are tested in situations where ballast water flow may not be linear nor consistent. The results of the testing should then be provided on the Type Approval Certificates to indicate within which ranges the filters will operate effectively, which pumping rates the tests were undertaken and under what circumstances limitations in the filter's effectiveness may occur. HAZID assessment; At
least two Type
Approved systems create hydrogen gas during the treatment phase, both of which have built in systems to keep the hydrogen levels below the 4% lower explosive limit. However, there is concern that the introduction of such systems counters the ongoing efforts of the shipping industry to eliminate all such safety and environmen- tal risks. Due to space limitations on tankers with deep-well pumps, retrof itting BWTS requires the installation of the equipment on deck. SOLAS allows equipment to be installed on tanker decks only after a safety assessment has been undertaken and is approved by the Administration. Noting the above examples of increasing safety risks aboard, the co-sponsors propose that the "Guidelines (G8)" should require the BWTS manufacturers to include the submission of HAZID assessments and mitigation measures.”. NA
The Naval Architect September 2012
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