Low temperature corrosion is mainly caused by sulphur.During combustion sulphur in fuel react with oxygen to form SO2 and further SO3, which react with water to form sulphuric acid vapours. Where metal temperatures are below 160 degree Celsius, sulphuric acids condenses and corrodes metal. The only defense is using load control cooling and using high TBN fuel.
Since very small needle lift is obtained in the test equipment result in an unequal pressure distribution in the cut off shaft resulting in a hard contact in a small area along with high frequency oscillations, low lubricity of test oil will increase the chance of seizure. Full lift and high lubricity of heavy oil eliminates this risk of seizure during normal operation.( Always open and clean slide type valves before testing as cold sticky heavy oil along with small clearances can cause restriction in the movement of the spindle).
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