Answer EKG Question 23
Q23. With regard to care of lubricating oils on board answer the following –
A. What is microbial degradation of lubricating oil and how is it prevented?
What methods are employed to ensure correct sampling for shore based testing?
B.
What action will you take If the testing results show abnormal values
of water content and TBN for crank case lube oil of a slow speed main
engine?
Answer: A. What is microbial degradation of lubricating oil and how is it prevented?
The term microbial degradation is sometimes referred to as biodegradation. It is the name given to the process whereby micro-organisms increase in number and decompose a hydrocarbon fuel or lubricant and eventually render it unfit for its duty.
This form of decomposition requires the presence of water together with other favorable environmental conditions including temperature, acidic conditions (pH value), and nutrients. With favorable environmental conditions the increase in microbial count may take place very quickly and cause rapid breakdown of the fuel or lubricant.
In the case of lubricating oils the additives in the oil may function as the nutrients.
The indications of attack may be seen as follows.
Creation of sulphurous gases having a smell similar to bad eggs.
Build up of yellowish-coloured film on the inside of crankcases and the polished steel surfaces at the sides or unworn parts of bearings.
The colour of the oil darkening.
The oil tending to become opaque with a milky appearance.
Inability of the lubricating oil centrifuge to separate water from the oil due to the creation of stable emulsions.
Plugging of lubricating oil filters due to thick sludges.
The effect of degradation usually shows up on bearings and bearing journals as a corrosive attack in the form of pitting in both the journal and the bearing, or a breakdown of the bearing surface. This may show itself as staining and in extreme cases as a breakdown of the bearing lining alloy.
The effect of degradation usually shows up on bearings and bearing journals as a corrosive attack in the form of pitting in both the journal and the bearing, or a breakdown of the bearing surface. This may show itself as staining and in
extreme cases as a breakdown of the bearing lining alloy.
Biocides and fungicides can be used to kill and prevent the spread of organisms within a distillate fuel oil. They can also be used in lubricating oils provided their use is approved by the oil supplier. Most of the treatments available cause some deterioration in the lubricating properties of the oil and their use should be carefully followed and observed.
The known organisms causing degradation are killed by preheating the lubricating oil to a temperature of 82.5°C during continuous separation treatment and when preparing to centrifuge the whole of the system oil charge.
Note The temperature at which lubricating oils are heated prior to centrifuging should never exceed the supplier's recommendations.
Care should be exercised in preventing leakage of cooling water into the system oils in both cross-head and trunk-piston engines. Modern non-toxic anti-corrosion additives may act as a nutrient to the organisms causing degradation.
some of the older additives are toxic to the organisms, but their use is banned in cooling systems used for heating low-pressure distilling plant producing portable water.
What methods are employed to ensure correct sampling for shore based testing?
1. Sampling location must not be varied and sample to be collected from the same sampling point, preferably on the main supply line into the main engine.
2. Engine must be in running at continuous rating and in normal operating range of load and temperature.
3. Before sample collection the sampling cock must be thoroughly flushed to remove any sludge accumulation.
4. A new sample bottle provided by the Labs for the sampling purpose of lube oil only must be used every time.
5. The sample should be fully identified with date, vessel name, type/grade of oil.
B. What action will you take If the testing results show abnormal values of water content and TBN for crank case lube oil of a slow speed main engine?
1. Source of water leakage to be traced and eliminated. This can be a cooler tube leaking or a sump drain line leaking.
2. Water can be removed by settling and draining method or by centrifugal purification.
3. Cooling water connections must always be isolated prior to the stopping of lubricating oil circulation. That will prevent the water from leaking cooler tubes to enter into water side.
4. The cause for decrease in TBN value is due to the presence of water and high temperature of the oil resulting in oxidation and subsequent acidity of the oil resulting in decrease of the TBN value. The subsequent action to be taken is to continue purification of the oil with the purifier. The cooler may require cleaning of the tubes to improve the cooling of the oil. By doing these the condition of the oil can be improved.
5. A high TBN value is the indication of leaking Cylinder oil into the sump. The leakage can be traced and rectified.
The term microbial degradation is sometimes referred to as biodegradation. It is the name given to the process whereby micro-organisms increase in number and decompose a hydrocarbon fuel or lubricant and eventually render it unfit for its duty.
This form of decomposition requires the presence of water together with other favorable environmental conditions including temperature, acidic conditions (pH value), and nutrients. With favorable environmental conditions the increase in microbial count may take place very quickly and cause rapid breakdown of the fuel or lubricant.
In the case of lubricating oils the additives in the oil may function as the nutrients.
The indications of attack may be seen as follows.
Creation of sulphurous gases having a smell similar to bad eggs.
Build up of yellowish-coloured film on the inside of crankcases and the polished steel surfaces at the sides or unworn parts of bearings.
The colour of the oil darkening.
The oil tending to become opaque with a milky appearance.
Inability of the lubricating oil centrifuge to separate water from the oil due to the creation of stable emulsions.
Plugging of lubricating oil filters due to thick sludges.
The effect of degradation usually shows up on bearings and bearing journals as a corrosive attack in the form of pitting in both the journal and the bearing, or a breakdown of the bearing surface. This may show itself as staining and in extreme cases as a breakdown of the bearing lining alloy.
The effect of degradation usually shows up on bearings and bearing journals as a corrosive attack in the form of pitting in both the journal and the bearing, or a breakdown of the bearing surface. This may show itself as staining and in
extreme cases as a breakdown of the bearing lining alloy.
Biocides and fungicides can be used to kill and prevent the spread of organisms within a distillate fuel oil. They can also be used in lubricating oils provided their use is approved by the oil supplier. Most of the treatments available cause some deterioration in the lubricating properties of the oil and their use should be carefully followed and observed.
The known organisms causing degradation are killed by preheating the lubricating oil to a temperature of 82.5°C during continuous separation treatment and when preparing to centrifuge the whole of the system oil charge.
Note The temperature at which lubricating oils are heated prior to centrifuging should never exceed the supplier's recommendations.
Care should be exercised in preventing leakage of cooling water into the system oils in both cross-head and trunk-piston engines. Modern non-toxic anti-corrosion additives may act as a nutrient to the organisms causing degradation.
some of the older additives are toxic to the organisms, but their use is banned in cooling systems used for heating low-pressure distilling plant producing portable water.
What methods are employed to ensure correct sampling for shore based testing?
1. Sampling location must not be varied and sample to be collected from the same sampling point, preferably on the main supply line into the main engine.
2. Engine must be in running at continuous rating and in normal operating range of load and temperature.
3. Before sample collection the sampling cock must be thoroughly flushed to remove any sludge accumulation.
4. A new sample bottle provided by the Labs for the sampling purpose of lube oil only must be used every time.
5. The sample should be fully identified with date, vessel name, type/grade of oil.
B. What action will you take If the testing results show abnormal values of water content and TBN for crank case lube oil of a slow speed main engine?
1. Source of water leakage to be traced and eliminated. This can be a cooler tube leaking or a sump drain line leaking.
2. Water can be removed by settling and draining method or by centrifugal purification.
3. Cooling water connections must always be isolated prior to the stopping of lubricating oil circulation. That will prevent the water from leaking cooler tubes to enter into water side.
4. The cause for decrease in TBN value is due to the presence of water and high temperature of the oil resulting in oxidation and subsequent acidity of the oil resulting in decrease of the TBN value. The subsequent action to be taken is to continue purification of the oil with the purifier. The cooler may require cleaning of the tubes to improve the cooling of the oil. By doing these the condition of the oil can be improved.
5. A high TBN value is the indication of leaking Cylinder oil into the sump. The leakage can be traced and rectified.
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