ARE WE "SEMPER PARATUS?"

By Louis Lemos


Much has been said and written about atmospheric contamination by exhaust emissions from ships, of all types and sizes and all flags. It has in fact become a world-wide problem requiring commensurate solutions. Fortunately, the International Maritime Organization (I.M.O.), has stepped up to the plate, devised and implemented appropriate legislation in attempting to minimize the discharge of Nitrogen Oxides (NO2), Sulfur Dioxides (SO2), Carbon Dioxide (CO2), Particulate Matter (PM), and related by-products within the above-mentioned effluence. Currently, such legislation is being enforced in seaports and within those areas designated as “Sulfur Emission Control Areas” (SECAs), adjacent to the continental coastline in various parts of the world. However, the contemporary solution to such outlawed exhaust emissions, which involves switching from conventional heavy fuel (380 centistokes), or from No. 2 Diesel fuel, to a distillate fuel with very low sulfur content, known as Ultra-Low Sulfur Fuel (ULSF), has caused problems of its own.

Typically, related incidents involving ULSF have adversely affected cylinder liner lubrication of large-bore, slow-speed main propulsion Diesel engines; and the diminished lubricity of ULSF has also been determined to be the cause of fuel injection pump binding of generator engines, resulting in loss of power. In one such incident, the generator failure resulted in a loss of steering power aboard a vessel heading into port. Further, It has been found that bio-fuel blends (also used as substitutes for conventional heavy fuel), are detrimental to elastomer sealing materials (a form of polymerized compounds), used in certain fuel transfer pumps oil seals, apparently due to acidity of the bio-fuel due to oxidation.

Since most ships are now powered by oil-burning Diesel engines, either direct-drive, geared-drive or Diesel-electric drive, the number of steam ships still in operation has diminished considerably. However, in the case of heavy oil tankers, such as VLCCs, (Very Large Crude Carriers), despite their large main propulsion Diesel engines, of 50,000 bhp or more, steam boilers play a prominent role in providing steam to sustain the cargo tank heating coils.

This is due to the fact that in cold climates such as found in Northern European seaports, the relatively low sea water temperature has chilled the heavy black crude oil to a such a high viscosity that the cargo can not be pumped out without being pre-heated by the steam-heated tank coils. In such instances, the critical factors become (a) the oil seals of the fuel oil transfer pumps and boiler service pumps and (b) the steam boiler burner tips. Are they currently designed for use with ULSF? Or do they also need to be replaced with ULSF-compatible components? The inevitable conclusion to all this is that solutions to certain problems that in turn, create problems of their own, are unacceptable and must be carefully evaluated before allowing one problem to being replaced by another potentially worse. Hence, responsible ship-owners can not afford to ignore the above-mentioned factors and should alert their crews to such potential problems and take appropriate corrective measures to ensure the required level of “readiness” to ensure in turn, the appropriate level of sea-worthiness.