Section 8 Control and monitoring
Clasification Society 2024 - Version 9.40
Clasifications Register Rules and Regulations - Rules and Regulations for the Classification of Special Service Craft, July 2022 - Part 10 Prime Movers - Chapter 2 Gas Turbines - Section 8 Control and monitoring

Section 8 Control and monitoring

Parent topic: Chapter 2 Gas Turbines

8.1 General

8.1.1 Control engineering systems are to comply with the requirements of Pt 16 Control and Electrical Engineering.

8.2 Overspeed protective devices

8.2.1 An overspeed protective device is to be provided for each shaft of main and auxiliary turbines to automatically shut off the fuel, near the burners, to prevent a dangerous overspeed condition of the shaft, unless it can be established that such a condition cannot arise.

8.2.2 The overspeed device is to be set to operate before the speed of the line exceeds the rated maximum speed by 10 per cent. For auxiliary turbines driving electric generators this setting may be increased to 15 per cent.

8.3 Speed governors

8.3.1 Where a main propulsion installation incorporates a reverse gear, electric transmission or controllable (reversible) pitch propeller, a speed governor, independent of the overspeed protective device, is to be fitted and is to be capable of controlling the speed of the unloaded power turbine without bringing the overspeed protective device into action.

8.3.2 Where an auxiliary turbine is intended for driving an electric generator, a speed governor, independent of the overspeed protective device, is to be fitted which, with fixed setting, is to control the speed within 10 per cent momentary variation and five per cent permanent variation when full load is suddenly taken off or put on. The permanent speed variations of a.c. machines intended for parallel operations are to be equal within a tolerance of ±0,5 per cent.

8.4 Lubricating oil failure

8.4.1 Main turbines are to have an arrangement whereby fuel is automatically shut off, near the burners, in the event of failure of the lubrication system.

8.5 Indication of temperature

8.5.1 Means are to be provided for indicating the temperature of power turbine exhaust gases.

8.6 Automatic and remote controls

8.6.1 Where gas turbines are fitted with automatic or remote controls so that under normal operating conditions they do not require any manual intervention by the operators, they are to be provided with the alarm and safety arrangements required by Pt 10, Ch 2, 8.6 Automatic and remote controls 8.6.2 and Table 2.8.1 Alarms and safeguards as appropriate. Alternative arrangements which provide equivalent safeguards will be considered.

8.6.2 The following turbine services are to be fitted with automatic temperature controls so as to maintain steady state conditions throughout the normal operating range of the turbine:

  1. Lubricating oil supply.

  2. Fuel oil supply, see also Pt 10, Ch 2, 8.6 Automatic and remote controls 8.6.3.

  3. Exhaust gas.

8.6.3 The fuel oil supply may be fitted with an automatic control for viscosity instead of the temperature control required by Pt 10, Ch 2, 8.6 Automatic and remote controls 8.6.2.

8.6.4 A means of manually shutting off the fuel in an emergency is to be provided at the manoeuvring station.

Table 2.8.1 Alarms and safeguards

Item Alarm Note
Overspeed High Automatic shutdown
Lubricating oil pressure for turbine and gearing 1st stage low Automatic shutdown
2nd stage low
Lubricating oil temperature High  
Lubricating oil filter differential pressure High  
Fuel oil supply pressure Low  
Fuel oil supply temperature High  
Bearing temperature High  
Exhaust gas temperature 1st stage high  
2nd stage high Automatic shutdown
Turbine vibration 1st stage high  
2nd stage high Automatic shutdown
Rotor axial displacement High Automatic shutdown, see Note 2
Flame and ignition Failure Automatic shutdown
Automatic starting Failure Automatic shutdown
Compressor inlet vacuum 1st stage high  
  2nd stage high Automatic shutdown
Control system Failure  

Note 1. Automatic or interlocked means are to be provided for clearing all parts of the main gas turbine of the accumulation of liquid fuel or for purging gaseous fuel, before ignition commences on starting or recommences after failure to start.

Note 2. Except for gas turbines with rolling element bearings.

Note 3.The Table contains the minimum list of alarms and shutdowns for a gas turbine. Additional alarms and shutdowns may be necessary as determined through risk-mitigating activities in response to the completed Risk-Based Analysis (e.g. FMEA) for the gas turbine.
Note 4.If specific alarms and shutdowns are not applicable for the gas turbine, sufficient evidence shall be produced to support such claims (e.g. Risk-Based Analysis such as FMEA).
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