EKG-Jan-21

Q1. Cast iron is the 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.

Q2. With respect to refrigeration gases used on-board vessels, answer the following: 

A. Explain the Ozone Depleting Potential (ODP) and Global warming potential (GWP) 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?

Q3. With reference to hydraulic steering gears, sketch and describe each of the following:

(A)Single failure concept;
(B)100% redundancy.

Q4. A. Describe the procedure to be adopted for the inspection of a safety valve fitted to an exhaust gas boiler stating, with reasons, which parts should receive particularly close attention. 

B. Describe the procedure for the setting of safety valves of exhaust gas-fired auxiliary boilers; 
C. Explain the action taken after the setting of safety valves as in (B).



Q5. A. Describe a transverse bow thrust unit using CPP, mention how it should be made to support and how the strength of thrust and reverse thrust are achieved;

B. State with reasons, a suitable prime mover for the controllable pitch propeller;
C. State whether the thrust unit delivers a relatively low-pressure head with high volume output or a high-pressure head with low volume output.

Q6.  How the ingress of seawater is prevented in an oil-lubricated stern bearing system. Should the system fail, describe the corrective action possible whilst the vessel is afloat? State the reasons for fitting two stern bearing oil header tanks in some cases?

Q7. 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.

Q8. (a) Describe the principle of coil-operated brake suitable for winches and other deck machinery. (b) Explain with suitable sketches how the windlass is relieved of strain when riding at anchor.

Q9. With regard to the 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 crankcase lube oil of a slow-speed main engine?