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Q7. With reference to electric arc welding:

a) Draw a labeled sectional sketch of a satisfactory butt weld. (5)

b) Briefly define the following defects that may occur and how they may have been caused (6)

i) Under cut

ii) Splatter

iii) Inclusion

iv) Blow hole

v) Incomplete root penetration

vi) Lack of fusion

c) Why is alternating current generally more popular then direct current for metal arc welding? (5)

Q9. Make a diagrammatic sketch of an exhaust gas boiler. Describe its construction and explain how it is maintained in an efficient condition. (16)

Q3. Explain the following briefly with reference to a domestic refrigeration system on board a ship. (16)

(a) Ingress of air into the freon system.

(b) Loss of refrigerant from a condenser.

(c) Water in the freon system.

(d) Icing of condenser external surface.

Q4. (a) Sketch a water-tight door and frame showing manner of attachment to bulkhead and the additional reinforcement carried by the bulkhead to compensate for the aperture (8)

(b) Explain how watertightness of the door and frame mating surface is ensured with an hydrostatic pressure tending to force the laces apart. (4)

(c) Describe the means of remote closing operation of the door and state how many closing stations there are and their position. (4) DONE

Q5. Sketch and explain the construction of a feed Check Valve. Why is it known as double shut off arrangement. (16)

Q6. with reference to auxiliary boiler water impurity define the effects of the following salts: (16)

(a) Calcium carbonate,

(b) Sodium chloride,

(c) Magnesium chloride,

(d) Calcium sulphate

Explain how the quantity of each is determined and controlled.

Q7. Write short notes on the following:

(a) Ultrasonic testing (8)

(b) Shaft earthing device (8)

Q8. (a) Sketch a screw displacement pump and explain its operation (10)

(b) State the factors which affect its efficiency. (6)

Q7) With reference to main air reservoirs:

(a) Explain with line sketch the manner in which mountings are attached to the shell (6)

(b) Explain why regular internal inspection is advisable (4)

(c) What are the areas that need particular attention during the inspection and survey of a main air reservoir. (6)