EKG-JUN-19

Q1. 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?

Q2. Cast iron is most widely used metal after steel in Marine Engineering. Most cast irons consist of graphite in steel like matrix. Discuss the variation of properties that may arise with reference to pearlitic grey cast iron and spherical grey cast iron. Describe briefly the treatment necessary to produce these two types of Irons.

Q3. With respect to properties of fuel oil, explain the significance of the following terms; (a) Calculated Carbon Aromaticity Inbox (CCAI). 
(b) Open flash point and Closed flash point. 
(c) The importance of Sodium to Vanadium Ratio.(d) Octane Number.

Q4. With reference to Vacuum Sewage System:
(i) Sketch & Describe a Vacuum Sewage System.
(ii) State the advantages of Vacuum Sewage System.
(iii) State the different causes of dropping vacuum.

Q5. With regards to main transmission shaft flange coupling arrangements: 
A. Sketch a hollow type coupling bolt and the hydraulic head/nut and loading rod which are used to fit it; 
B. Describe how the bolt is fitted; 
C. State the advantage of the hollow coupling bolt as compared to the traditional type of coupling bolt.

Q6. With respect to refrigeration gases used on-board vessels, answer the following 
A. Explain Ozone Depleting Potential (ODP) of conventional refrigerant gases. 
B. Name the alternate refrigerant gases available and being used onboard.
C. What steps are taken to minimize the release of refrigerant gases from the plant during normal operation and maintenance activities.

Q7. As second engineer onboard a tanker, describe the procedure for presenting a Main Boiler for survey by a classification society.

Q8. Detail the desirable properties of a refrigerant. Make a table and compare following refrigerants for use in a provision cooling plant for a 50000 DWT Oil tanker: R-22, R-134a.

Q9. Sketch a sealing arrangement for an oil lubricated stern tube. Identify the common forms of seal failure; State how oil loss due to seal failure can be restricted whilst on passage? What is the material used for sealing rings and propeller shaft liner?