Servicing a Gas Turbine includes various inspections through out the machine. Preventative maintenance on Gas Turbines is the best method for avoiding catastrophic failure. When conducting Gas Path inspections a main factor to consider is:
- Can I see any defects that have the ability to cause downstream damage?
- Is there any signs of contamination indicating a lack of performance with my turbine air filtration system?
A foreign object like a loose or corroded fastener in the air intake could destroy a machine if it came free and was ingested into the Gas Turbine compressor.
Working from the front to the back of the Gas Turbine there is numerous inspections to execute during a Gas Turbine service. This service inspection is for the Air Inlet Area of the machine and what to look for.
Prior to starting service inspections of the Gas Turbine Air Inlet various equipment isolation’s should be put into place for your safety.
- Fuel gas supply
- Liquid fuel supply
- Start system
- Plant specific Fire & Gas MOS
- Fire system; Inhibit key additionally:
- Water Mist System – Nitrogen bottles closed and water outlet to drain (minimum)
- CO2 System – Discharge heads removed (minimum)
- Generators have the potential for unplanned rotation. On “Cold End Drive” machines be sure to include a generator isolation
Gain Access to Air Inlet:
- Remove air intake access panels
- Assess access method.
- Some facilities deem accessing the air intake (head only) a “confined space”. Ensure you follow local safety rules and regulations
- If entering ensure that your pockets are free of items that could be left within the space
- Conduct gas monitoring prior to entry or use of non-IS devices. This area can have residual gas present if there is leakage past gas shut off valves
- Inspect turbine front frame, inlet guide vanes and duct area for corrosion and contamination.
- This inspection gives you a good idea of filter performance
- Special mention should be made of the location of any salt, dirt deposits and corrosion
- Sometimes #1 bearing oil seals leak into the gas path. If this occurs the compressor will contaminate quickly and combustion will be poor and potential to cause burns to the combustion liner and 1st stage turbine nozzles
- Inspect FOD Screen/Mesh for corrosion or degradation
- If pieces of the screen break away this can cause damage to the engine if ingested
- Inspect rivnut/captive nut integrity
- Rivnuts can corrode and become a FOD risk
- Inspect lower duct cleanliness
- If water or contaminants is pooling in this location it is an indicator that your offline turbine intake drain system is not functioning correctly
- Inspect integrity of any flexible expansion joints between turbine inlet and package duct
- Expansion joints can degrade over time and become an entry path for unfiltered air
- Inspect removed access panel seals
- Seals can degrade over time and become an entry path for unfiltered air
Rectification of Defects:
Immediately fix any defects that are risks of foreign object ingestion into the gas turbine as these can cause catastrophic damage.
Consider fixing any seals or duct leakage that is allowing ingestion of unfiltered air. Clean air will extend time between compressor detergent washing and improve combustion performance giving your Gas Turbine hot section a longer life.
Reinstate Access Panels:
Prior to reinstating access panels it is important to ensure that your duct area is free from foreign item. Best practice is having the area peer checked by a team mate just in case you missed something.
Inspection of an air intake is a very basic task. However the Air Intake can tell you a lot about how clean the air is that is being supplied for combustion. Attention to detail during these checks followed by remedial actions if you find things will help increase the life of your Gas Turbine.
If you are not comfortable executing Gas Turbine Servicing on your own or require resources to execute the work. We are specialists at executing Gas Turbine Servicing in Western Australia.