Overhauling industrial power turbines by module replacement
Overview
This standard identifies the competences you need to carry out a complete overhaul of an industrial power turbine, in accordance with approved procedures. The power turbine to be overhauled will have been isolated, disconnected and removed from its normal operating environment, and the overhauling activities may take place in a maintenance environment or manufacturer's workshop.
In carrying out the overhauling operations, you will be required to follow laid-down procedures and use specific dismantling and rebuilding techniques. The overhauling activities will involve removing any protective outer casing, removing all ancillary equipment and components and dismantling the power turbine down to the various sub- assembly/modules, such as fan case, front fan, compressor module, combustor module, turbine module and gearbox.
You will then be expected to rebuild the power turbine, which will involve fitting replacement or overhauled sub- assembly/modules and the replacement of all damaged, worn and 'lifed' components. The overhauling activities will include making all necessary checks and adjustments to ensure that components/modules are correctly replaced, positioned, aligned, adjusted, torque loaded, locked and fastened, and that the correct sealants are used.
Your responsibilities will require you to comply with organisational policy and procedures for the overhaul of the power turbine, and to report any problems with the overhauling activities or with the tools and equipment used that you cannot personally resolve, or that are outside your permitted authority, to the relevant people. You must ensure that all tools, equipment and materials used in the overhauling activities are removed from the work area on completion of the activities, and that all necessary job/task documentation is completed accurately and legibly. You will be expected to work with a minimum of supervision, taking personal responsibility for your actions and for the quality and accuracy of the work that you carry out.
Your underpinning knowledge will provide a good understanding of your work, and will provide an informed approach to applying appropriate overhauling techniques and procedures to power turbines. You will understand the dismantling and reassembly methods and procedures used, and their application. You will know how the power turbine functions, the purpose of the individual components and associated defects, in adequate depth to provide a sound basis for carrying out the overhauling activities to the required specification. In addition, you will have sufficient knowledge of these components to ensure that they are fit for purpose and meet the specifications, thus providing a sound basis for carrying out the re-assembly.
You will understand the safety precautions required when carrying out the overhauling activities associated with power turbines, especially those for lifting, handling and supporting the equipment being removed and replaced. You will be required to demonstrate safe working practices throughout, and will understand your responsibility for taking the necessary safeguards to protect yourself and others in the workplace.
Performance criteria
You must be able to:
- work safely at all times, complying with health and safety and other relevant regulations, directives and guidelines
- follow the relevant overhauling schedules to carry out the required work
- establish the components/modules to be removed and, where appropriate, mark components to aid re-assembly
- ensure that any stored energy or substances are released, safely and correctly
- ensure that all removed components/modules are correctly identified and stored in the correct location
- carry out the overhaul to the agreed level, using the correct tools and techniques
- report any instances where the overhauling activities cannot be fully met, or where there are identified defects outside the planned overhauling schedule
- complete the relevant documentation, in accordance with organisational requirements
- dispose of unwanted components, waste materials and substances, in accordance with safe working practices and approved procedures
- deal promptly and effectively with problems within your control and report those that cannot be solved
Knowledge and Understanding
You need to know and understand:
- how to work safely at all times, complying with health and safety and other relevant regulations, directives and guidelines
- the hazards associated with overhauling power turbines and how to minimise them and reduce any risks
- the importance of wearing protective clothing (PPE) and other appropriate safety equipment during the overhauling activities
- how to obtain and interpret drawings, specifications, manufacturers' manuals, history/maintenance reports, and other documents needed in the overhauling process
- how to carry out currency/issue checks on the specifications you are working with
- the quality control procedures to be followed during the overhauling operations
- the procedure for obtaining replacement parts, materials and other consumables necessary for the overhaul
- company policy on the repair/replacement of components/modules during the overhauling process
- terminology used in power turbines and turbine modules
- the basic principles of how the turbine functions, its operating sequence, the working purpose of individual units/components/modules and how they interact
- the extent to which the equipment is to be dismantled for overhaul
- the sequence to be adopted for the dismantling/reassembling of various types of turbine assemblies
- the techniques used to dismantle the power turbine without damage to the components or surrounding structure
- the need to protect the system integrity by ensuring that exposed components are correctly covered/protected
- how to lift and move large components/modules and assemblies; the methods and equipment used to transport, handle and lift the components during the overhauling activities
- the need to ensure that lifting and handling equipment is within its current certification dates
- methods of checking that components are fit for purpose, how to identify defects and wear characteristics, and the need to replace `lifed' and consumable items
- the uses of measuring equipment
- methods of reassembling the power turbine, using new or previously overhauled modules
- how to make adjustments to replaced components/assemblies/modules to ensure that they function correctly
- the various mechanical fasteners that are used, and their method of removal and replacement
- the various types of electrical connector that are used, methods of unlocking, orientation indicators, and locating and locking in of the connections
- the tools and equipment used in the overhauling activities, and how to check that they are in a safe and usable condition
- the importance of ensuring that all tools are used correctly and within their permitted operating range
- the importance of ensuring that all tools, equipment and components are accounted for and returned to their correct location on completion of the overhauling activities
- the procedure for the safe disposal of waste materials
- the need to complete overhaul documentation and/or reports following the overhauling activity
- the problems that can occur during the overhauling activity, and how they can be overcome
- the extent of your own authority and to whom you should report if you have a problem that you cannot resolve
Scope/range
Scope Performance
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- Carry out all of the following during the overhaul of the power turbine:
- obtain and use the appropriate dismantling documentation
- adhere to procedures or systems in place for risk assessment, personal protective equipment and other relevant safety regulations and procedures to realise a safe system of work
- provide and maintain safe access and working arrangements for the work area
- ensure that any remaining oil, fluids and fuel have been drained/removed before breaking into the system
- ensure that the power turbine is suitably supported, and that appropriate lifting and handling equipment is available
- carry out the overhauling activities, following good practice/approved procedures
- ensure that components and surrounding structures are maintained free from damage and foreign objects
- return all tools and equipment to the correct location on completion of the activities
- leave the work area in a clean and safe condition on completion of the activities
- leave the power turbine in a condition ready for testing
- Dismantle a power turbine, to include removing four of the following sub-assemblies/modules:
- outer casings
- exhaust/reheat assembly
- combustor module
- turbine
- front fan and fan case
- compressor module
- air intake ducts
- gearbox
- Carry out all of the following activities on the power turbine being overhauled:
- cleaning parts prior to dismantling
- carrying out pre-disassembly checks
- proof-marking/labelling of components to aid reassembly
- removing turbine covers/casing
- disconnecting and removing wires/cables, and attaching suitable cable identification markers
- removing all ancillary components
- disconnecting and removing pipework
- dismantling equipment to unit/sub-assembly level
- dismantling units to component level
- checking components for wear and serviceability
- replacing all damaged or defective sub-assemblies and components
- replacing all 'lifed' and consumable items (such as seals, bearings, gaskets)
- removing and replacing components having interference fits (such as by expansion, contraction, pressure)
- applying gaskets and sealant/adhesives
- re-assembling components to sub-assembly level
- re-assembling sub-assemblies to unit level
- setting and adjusting replaced components
- refitting all ancillary components
- reconnecting all pipework
- refitting cable harnesses
- refitting electrical units and connecting to cable
- electrical bonding of components
- securing components using mechanical fasteners and threaded devices (such as nuts, bolts, circlips, pins)
- tightening fastenings to the required torque
- applying bolt locking methods (such as split pins, wire locking, lock nuts, stiff nuts, swage nuts)
- Replace/refit a range of power turbine components and sub-assemblies, to include: four of the following engine modules:
- front fan and fan case
- turbine
- compressor module
- gearbox
- exhaust/reheat assembly
- air intake ducts
- combustor module
- outer casings
Plus eight of the following types of component:
9. curvic couplings
10. wire thread inserts
11. bearings
12. pipes and unions
13. static seals/gaskets
14. mechanical controls (such as plungers, springs, rollers)
15. dynamic seals
16. shims and packing
17. electrical units and controls (such as solenoids, motors, switches)
18. mechanical securing devices
19. locking devices
20. other specific components
- Carry out checks and tests on the overhauled power turbine, to include all of the following:
- visual inspection for completeness of all operations
- visual inspection for freedom from damage or foreign objects
- applying protection to openings to prevent entry of contaminating debris
- carrying out any `special-to-type' test rig checks
- Overhaul a power turbine in compliance with one of the following:
- BS, ISO or BSEN standards and procedures
- customer standards and requirements
- company standards and procedures
- turbine manufacturer's requirements