A good maintenance program is needed to maximize the availability of the equipment. Advance planning for maintenance is essential to reduce downtime. The parts that require the most careful attention are the combustors and the section exposed to the hot gases that are discharged from the combustors. These are known as the hot-gas-path parts. They include combustion liners, cross-fire tubes, transition pieces, turbine nozzles, turbine stationary shrouds, and turbine buckets.
The recommended maintenance of most manufacturers for heavy-duty gas turbines is oriented toward:
Minimum downtime for inspection and overhauls
On-site inspection and maintenance
Use of site workers to disassemble, inspect, and reassemble
Periodic maintenance is also required for control devices, fuel-metering equipment, and gas turbine auxiliaries.
The main contributors of downtime are normally controls and accessories, combustor, turbine, generator, and the balance of the plant. The outages caused by controls and accessories normally have a short duration; however, they are frequent. The remaining systems normally cause longer-duration outages.
The maintenance and instruction manual outlines the inspection and repair requirements. Some manufacturers also provide a system of technical information letters (TILs). These TILs update the information that is included in the maintenance and instruction manual. This ensures optimum installation, operation, and maintenance of the unit. Some TILs provide technical recommendations to resolve problems and improve operation, safety, and reliability of the machine. It is advisable to follow the recommendations provided in the TILs.
Most heavy-duty gas turbines can be maintained on-site.
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