Question

Damage has occurred to the main engine valves and the fuel supplied at a particular port is suspected. The owner's case, however, in the subsequent dispute may be weak because the fuel was ordered specifying only type and viscosity.

(a) Apart from fuel specification, describe how you, as Second Engineer, should have assisted the owner's case when receiving the suspect fuel.

(b) Describe the ISO fuel standard that is to be used when ordering fuel.

(c) Explain how the correct fuel standard is selected.

(d) Suggest, with reasons, why particular mention should be made of certain elements that might not be included in the fuel standard.

Answer 1

Part (a)

As a second engineer, I would have sent the sample of suspected fuel for laboratory analysis to receive a detailed report about the impurities present in the fuel. Impurities such as vanadium, sodium, asphaltenes in unacceptable quantity will lead to damage to the machinery parts. This detail could have assisted the surveyor's case. Listed below is the ill effects:

Vanadium combines with sodium and sulphur during combustion process to form eutectic compounds [Penta Sodium Vanadate] which lowers the melting point to about 450°C. These molten compounds are very corrosive and attack the components such as exhaust valves & piston crown.
A high asphaltene content indicates that fuel may be difficult to ignite and will burn slowly. This will contribute to deposit formation in combustion chamber and exhaust system, especially at low engine loads.

Part (b)

Recognised fuel standards ISO 8217-2017 for Marine residual fuel RMG 380

Part (c)

The correct fuel standard should be selected by considering the following:

Consult the engine maker’s manual to identify permissible fuel grades for the specific engine type. This ensures compatibility and compliance with the engine’s design and operational parameters.
Adhere to specific fuel quality regulations in areas such as Emission Control Areas (ECAs), where low-sulphur fuel may be required. Engine makers may provide specific recommendations for these regions to avoid operational issues.
Use the ISO 8217-2017 fuel quality standard, which defines limits for key parameters such as sulphur content, viscosity, water, catfines, and ash, ensuring consistent and safe fuel quality.

Part (d)

Importance of Specifying Elements Excluded from Fuel Standards:

Ash Content:

Inorganic impurities like sand, nickel, aluminium, and silicon contribute to abrasive wear and can damage fuel pumps and cylinder liners.

Vanadium:

Combines with sodium and sulphur, leading to high-temperature corrosion on exhaust valves, turbochargers, and piston crowns.

Catfines (Aluminium and Silicon):

Abrasive particles in residual fuel oils that can cause severe wear on fuel pumps, valves, and cylinder liners.

Water:

Leads to cavitation damage in fuel pumps and valves, ignition delays, and potential vapour lock during combustion.

Asphaltenes:

High levels contribute to sludge formation, leading to deposits in the combustion chamber and exhaust systems, especially under low-load conditions.

Sulphur:

Excess sulphur forms acids that cause cold corrosion, particularly in areas with low temperatures in the exhaust system.

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