How to Inspect, Repair, or Replace GT Inlet and Exhaust System Components

CLARIDA on inlet and exhaust systems. Clarida, president of Integrity Power Solutions LLC, is well known to CCJ subscribers for his insightful article on gas-turbine (GT) exhaust systems in the 2010 Outage Handbook and his recent webinar on the same subject, enabling you to choose between reading or listening for guidance on this important subject. Both cover virtually all of what Clarida had to say at CTOTF on exhaust systems. Not covered, however, were his comments on inlet-system inspections. Another alternative: Users registered on the CTOTF website ( will be able to access Clarida’s presentation, as well as most others from the San Diego meeting, by mid October. If you’re not yet registered, do so today.

The most common inlet-system concerns of owner/operators, Clarida said, are the following:

• Safety—inlet acoustics.

• Operations—engine compressor FOD (foreign object damage) and deposits.

• Maintenance—inlet corrosion (Figs 6, 7).

6. Inlet-silencer panel corrosion

7. Frame corrosion on evap cooler

• Performance—equipment failure, high pressure drop.

To address these potential issues, Clarida suggested checking the inlet system thoroughly before each outage. His key points were:

• Develop an inlet acoustic-performance baseline.

• Listen for internal noise so you don’t miss a possible failure in the internal insulation system.

• Inspect expansion joints for breaches that allow unfiltered ambient air to enter the compressor.

• Inspect for other avenues for air bypass, including shell-plate corrosion, improper sealing of filter elements, etc. It’s easy to find holidays in the shell of the inlet air house and associated ductwork by standing inside the darkened structure on a bright sunny day (with the engine off, of course) and looking for rays of sunlight.

• Evaluate the inlet system to see if it’s compatible with the actual operating environment. Oftentimes little real engineering is done on inlet systems during the plant design phase and the “standard” components installed may not be meeting expectations.

During the outage, he recommended checking the following:

• Integrity of internal insulation and liners.

• Internal corrosion.

• The entire filter house for proper installation of filter media and evap-cooler media or fogging nozzles, if installed.

• Integrity of the inlet trash screen.

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