041/17/Gen.Inf. Factors leading to off-specification

The West of England P&I Club advises practical measures to avoid off-specification bunker disputes and sets out the legal and claims handling steps that should be taken in the event of an off-specification bunker claim arising.

In a pair of latest loss prevention publications, the Club handles with Bunker Quality Disputes and Legal & Claims Handling Considerations highlighting that the consequences of burning off-specification bunkers can be severe, possibly leading to the breakdown of the vessel’s
machinery.

The Club notes that fuel specifications contain numerous parameters that need to be satisfied. Using fuel that does not meet these requirements or burning contaminated fuel may cause machinery problems. Factors that need to be considered include:

Ash – A non-combustible material that can form deposits on exhaust valves and turbocharger blades causing loss of efficiency and damage

Asphaltenes – May affect the ignition performance of engines and cause a build-up of sludge in storage tanks

Calculated Carbon Aromaticity Index (CCAI) – High CCAI fuels may have poor ignition and combustion qualities. Medium and high speed diesel engines and older diesels may be particularly affected at low or partial load

Micro carbon residue – High levels can cause carbon deposits to form on fuel injectors

Density – High density can cause poor purifier performance, increasing the carryover of abrasives and contaminants.

Low viscosity – May cause internal leakages in the fuel system and poor combustion if combined with high density.

High viscosity – May cause pumping problems and poor combustion if not heated to the correct temperature

High aluminium/silica (catalyst fines from the refinery) – Very hard and abrasive, “cat fines” can cause mechanical damage and rapid and excessive wear on an engine’s piston rings and ring grooves, cylinder liners, fuel injection pumps and injectors

Hydrogen sulphide – A highly toxic gas which can form in the head space of storage tanks, affecting personnel in the vicinity of the tank vents, when opening manholes or entering empty tanks.

Incompatibility with other bunkers on board – May result in the formation of waxes and tar-like solids.

Iron (Fe) – A non-combustible material that can form deposits on exhaust valves

Lubricity (distillate fuels only) – May lead to poor lubrication of fuel pump components and subsequent seizure of pumps. In general, the lower the sulphur content the more likely that this will be a problem.

Nickel (Ni) – A non-combustible material that can form deposits on exhaust valves and turbocharger blades causing loss of efficiency and damage.

Potassium (K) – May lead to increased post-combustion deposits and possibly deposits on and corrosion of turbocharger nozzle rings. Can also affect Selective Catalytic Reduction (SCR) units

Pour point – At lower sea water temperatures the transfer and filtration of fuels with a high pour point may be difficult without heating.

Sediment (Total Sediment Potential – TSP) – May increase the possibility of sludge forming in centrifuges and filters causing blockages

Sodium (Na) – May cause corrosion on exhaust valves, increased ash deposits in the exhaust gas system and in turbochargers, particularly when combined with vanadium

Vanadium (Va) – Similar problems to those associated with sodium, particularly if the Va/Na ratio is in the region of 3:1

Waste products – Used lubricating oil is sometimes added to fuel oil, it can contain high concentrations of wear metals which may lead to problems with ash formation

Water – High levels can cause loss of energy, sludge formation, as well as corrosion of fuel injection equipment and exhaust valves. Sea water contamination can cause corrosive compounds to form

Find out more details on how to handle Bunker Quality Disputes by reading the following guides issued by the West of England P&I Club

Find out more details on how to handle Bunker Quality Disputes by reading the following guides issued by the West of England P&I Club

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Thank you & Best Regards,

Eng. Dimitrios Nikolaos Spanos
Lead Maritime Auditor / Principal Surveyor
Member of IRCA, IIMS, ELINT, HELMEPA & Nautical Institute

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