Section 4 Design
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 4 Design

Section 4 Design

Parent topic: Chapter 2 Gas Turbines

4.1 General

4.1.1 All parts of turbines, compressors, etc. are to have clearances and fits consistent with adequate provision for the relative thermal expansion of the various components. Special attention is to be given to minimising casing and rotor distortion under all operating conditions.

4.1.2 Turbine bearings are to be so disposed and supported that lubrication is not adversely affected by heat flow from adjacent hot parts. Effective means are to be provided for intercepting oil leakage and preventing oil from reaching high temperature glands and casings.

4.2 Vibration

4.2.1 Care is to be taken in the design and manufacture of turbine and compressor rotors, rotor discs and rotor blades to ensure freedom from undue vibration within the operating speed range. Where critical speeds are found by calculation to occur within the operating speed range, vibration measurements may be requested in order to verify the calculations, see Pt 13 Shaft Vibration and Alignment.

4.3 Containment

4.3.1 Gas turbines are to be designed and installed so as to contain debris in the event of an internal failure.

4.3.2 The gas turbine is to be located such that any flying debris resulting from a failure will not endanger the craft, other machinery, occupants of the craft or any other persons.

4.3.3 Where an acoustic enclosure is fitted which completely surrounds the gas generator and the high pressure oil pipes, a fire detection and extinguishing system is to be provided for the acoustic enclosure.

4.4 External influences

4.4.1 Pipes and ducting connected to casings are to be so designed that no excessive thrust loads or moments are applied by them to the compressors and turbines.

4.4.2 Platform gratings and fittings in way of the supports are to be so arranged that casing expansion is not restricted.

4.4.3 Where main turbine seatings incorporating a tank structure are proposed, consideration is to be given to the temperature variation of the tank in service to ensure that turbine alignment will not be adversely affected.

4.4.4 For securing arrangements, including resilient mounting, see Pt 9, Ch 1 General Requirements for Machinery.

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