Q1. (a) Sketch a Stress/Strain curve for a mild steel test specimen. (2)
(b) With reference to the curve sketched in part (a), explain EACH of the following:
(i) Modulus of elasticity. (2)
(ii) Percentage elongation. (2)
(iii) Ultimate tensile stress. (2)
(iv) Yield stress. (2)
Q2. With reference to pneumatically operated control valves:
(a) State FOUR the reason for fitting valve positioners. (4)
(b) Explain valve hysteresis, stating how it affects the process. (2)
(c) State the immediate action to be taken to restore control upon failure of the positioner bellows. (2)
(d) State the difference between fail safe and fail set. (2)
Q3. (a) Define propeller slip, explaining how it is calculated. (2)
(b) State, with reasons, FOUR conditions which will affect the propeller slip. (8)
Q5. With reference to centrifugal pumps
(a) Sketch double entry impeller showing directions of flow (3)
(b) Explain why double entry impellers are fitted (2)
(c) Explain, with the aid of a Head versus Flow diagram, why a two-speed pump is preferable to throttling where high and low capacities are demanded for a large sea water circulating pump. (5)
Q6. (a) State the regulations pertaining to the main and auxiliary steering gear with reference to EACH of the following:
(i) Rudder angle and time of operation. (2)
(ii) Electrical supply. (3)
(b) With reference to a hydraulic steering gear, explain EACH of the following:
(i) The factors that may contribute to the failure of a hydraulic pipe coupling; (2)
(ii) What is meant by the single failure concept. (3)
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