The securing of bunkers of an acceptable quality depends on a variety of factors such as availability, demand, area, choice of suppliers etc. The problems have, to a certain degree, fluctuated with the bunker prices. The market has seen fuels contaminated with waste chemicals detrimental to the health of the crew as well as damaging to the ships engines. For many years, it has been normal in certain areas of the world to dispose of used automotive lubricants in bunkers, thus possibly adding to engine operating problems.High-density fuels which far exceed the capabilities of the onboard fuel treatment plants are being delivered to vessels.. Water in the fuels is not uncommon, resulting in emulsified fuels and fuels that cannot be treated in shipboard fuel treatment plants. Some of the problems mentioned result in damages that are insured against, but in most cases the associated costs fall below the deductible. Occasionally, blending contaminated fuel with good quality fuel may solve the problem. In other instances, the damages in the form of wear and tear of moving parts are so great that the vessel has to divert to an emergency port for major repairs.
We see mainly three problems:
Catfines, aluminium and silicon resulting from the refinery cracking processes, are very abrasive to ships machinery, unless properly removed. The end result can be machinery damage unless the Catfines are removed to an acceptable level (contact your engine manufacturer) through effective fuel treatment onboard, i.e. optimum use of the centrifuges. The mode of centrifuge operation must be discussed with the manufacturer as the type and year of manufacture of the separators is of significance.
As the global demand for premium products such as gasoline, jet fuel, heating oils and gas oils has increased sharply, the use of refinery conversion processing have markedly influenced the quality of the end product, the residual component which is the major component used for blending Intermediate Fuel Oil (IFO) for ships. The result is fuels with higher density, carbon residue, sulphur etc. Practically every parameter has increased significantly throughout the refinery processing.
Ships fitted with older centrifuges are unable to effectively treat such fuels, particularly the high density products, i.e. fuel densities of 990 Kg/m3 and above. Centrifuge manufacturers offered upgrade kits for the old separators, but few operators invested in these kits.
|3||Poor ignition quality is another problem that has arisen recently. The standard laboratory tests do not test the ignition quality, and it is not a part of the ISO 8217 Fuel Standards. The problem is normally associated with low viscosity/high density fuels. If a vessel receives this type of fuel, the ship should keep temperatures as high as possible, thus avoiding low load operation. Gard Services has seen a number of claims in the last few years where the vessel has had to be assisted to an emergency port. The use of inferior ignition quality fuels may well result in major repairs to the vessels engine(s).|
Owners should be aware that the increased demand from shore side industries for premium products has resulted in a deterioration of IFO used in marine engines. Compounding the problem is the demand from shipowners for high performance lighter engines.
IFO used as bunkers should, as a minimum, meet the requirements of the specifications set out in ISO 8217, latest issue. Bunker testing agencies such as DnV Petroleum Services (DnVPS) and Lloyds Registers FOBAS are set up to monitor that this is the case.
If the vessel has performance difficulties and poor ignition quality is suspected despite a satisfactory CCAI value, a further test for the ignition quality should be performed. Fueltech, FOBAS and DnVPS can perform these services (see Gard Services Loss Prevention Circular 04-01, Charterers Liabilities and Bunkers).
If the vessel is in the unfortunate situation of having received a high Catfines fuel, and has to use the fuel, owners should be prepared for a succession of replacements of plungers, nozzles and other moveable engine parts. A normal full set of spares may not be sufficient to see the problem through. The fuel testing service provider should also be contacted, together with your centrifuge manufacturer and fuel supplier for advice and decision-making.
Separators must be in prime conditions. Considerations should be given to replacing separators manufactured prior to 1984/1985.
If the vessel has been on extended lay-up, Catfines and other impurities may settle in the bunker tanks if a sufficient amount of bunkers remain onboard during the lay-up period. When subsequently re-commissioned, these Catfines and impurities are likely to be stirred up in heavy seas and cause damage to the engine(s). Therefore, consideration should be given to the cleaning of bunker tanks prior to bringing a vessel out of an extended lay-up to prevent the occurrence of this type of problem.
The settling of Catfines is a continuous process taking place onboard every seagoing vessel. As a rule, fuel tanks should be cleaned regularly. Settling and daily service tanks should be cleaned at least once a year. This messy, but important task would save ship operators a lot of problems.
Gard Services would like to thank and acknowledge Mr. Kjell Hauglands assistance in preparing this circular.