Section 6 Safety arrangements on engines

6.1.1 Cylinder relief valves are to be fitted to engines having cylinders over 230 mm bore. The valves are to be loaded to not more than 40 per cent above the designed maximum pressure and are to discharge safely so that no damage occurs.

6.1.2 In the case of auxiliary engines, consideration will be given to the replacement of the relief valve by an efficient warning device of overpressure in the cylinder.

6.1.3 Scavenge spaces in open connection with cylinders are to be provided with explosion relief valves.

6.2.1 An efficient governor is to be fitted to each main engine so adjusted that the speed does not exceed that for which the engine is to be classed by more than 15 per cent.

6.2.2 Oil engines coupled to electrical generators which are the source of power for main electric propulsion motors are to comply with the requirements for auxiliary engines in respect of governors and overspeed protection devices.

6.3.1 Auxiliary engines intended for driving electric generators are to be fitted with governors which, with fixed setting, are to control the speed within 10 per cent momentary variation and five per cent permanent variation when full load is suddenly taken off or, when after having run on no-load for at least 15 minutes, load is suddenly applied as follows:

1. For engines with BMEP less than 8 bar, full load, or

2. For engines with BMEP greater than 8 bar, per cent, but not less than one-third, of full load, the full load being attained in not more than two additional equal stages as rapidly as possible.

6.3.2 Emergency engines are to comply with Pt 5, Ch 2, 6.3 Auxiliary engine governors 6.3.1 except that the initial load required by Pt 5, Ch 2, 6.3 Auxiliary engine governors 6.3.1.(b) is to be not less than the total connected emergency statutory load.

6.3.3 For alternating current installations, the permanent speed variation of the machines intended for parallel operation are to be equal within a tolerance of ±0,5 per cent. Momentary speed variations with load changes in accordance with Pt 5, Ch 2, 6.3 Auxiliary engine governors 6.3.1 are to return to and remain within one per cent of the final steady state speed. This should normally be accomplished within five but in no case more than eight seconds. For quality of power supplies, see Pt 6, Ch 2, 1.4 Application 1.4.3.

6.4.1 Each main engine developing 220 kW or over which can be declutched or which drives a controllable (reversible) pitch propeller, also each auxiliary engine developing 220 kW and over for driving an electric generator, is to be fitted with an approved overspeed protective device.

6.4.2 The overspeed protective device, including its driving mechanism, is to be independent of the governor required by Pt 5, Ch 2, 6.2 Main engine governors or Pt 5, Ch 2, 6.3 Auxiliary engine governors and is to be so adjusted that the speed does not exceed that for which the engine and its driven machinery are to be classed by more than 20 per cent for main engines and 15 per cent for auxiliary engines.