VANADIUM IS A FOUND IN FUEL USED IN MAIN ENGINE. THIS VANADIUM CAUSES A SERIOUS CORROSION IN EXHAUST VALVE WHEN PRESENT WITH SODIUM IN A RATIO OF 3:1 I.E (V/Na)=(3:1). THIS CORROSION IS KNOWN AS HOT CORROSION AS IT HAPPENS AT HIGH TEMPERATURE ONLY DUE TO THE FORMATION OF V2O5 MAINLY AT A TEMPERATURE ABOVE 530°C.
PREVENTION :-
- KEEP THE EXHAUST TEMPERATURE BEFORE TURBOCHARGER BELOW 450°C.
- KEEP SCAVENGE AIR TEMPERATURE AND COOLING WATER TEMPERATURE LOW AT HIGH LOAD AND HIGH ON LOW LOAD.
- TURBOCHARGER WASHING TO BE CARRIED OUT TO WASH AWAY V2O5 DEPOSIT.
- EFFECTIVE PURIFICATION.
- EXHAUST VALVE IS COATED WITH STELLITE COATING.
- ROTATION OF EXHAUST VALVE TO CLEAR ANY V2O5 DEPOSIT ON THE VALVE AND SEAT