Gas turbines are critical components in power generation and industrial applications, where efficiency and reliability are paramount. One essential maintenance technique used to assess turbine health without requiring disassembly is borescope inspection. This article explores the importance, process, and benefits of borescope inspections inside gas turbines, accompanied by visual documentation.
Why is Borescope Inspection Important?
Borescope inspections are essential for identifying issues such as:
- Cracks or fractures in turbine blades
- Foreign object damage (FOD)
- Corrosion and oxidation
- Excessive wear and tear
- Blockages or contamination
- Thermal fatigue and coating degradation
During scheduled overhauls of gas turbines, in addition to the visual surface inspections mentioned above, the entire set of high-pressure turbine (HPT) blades is typically removed. At this stage, engineers use a borescope to inspect the air passages at the base of the blades in greater detail. This allows for a thorough examination of blades suspected of having surface damage and an individual assessment of blockage, oxidation, and corrosion conditions. These internal airways directly affect cooling efficiency and overall turbine vortex performance. If a single blade fractures during operation, the costs and effort required for shutdown and repairs can be immense. Therefore, the more detailed the inspection, the better preventive repairs or replacement measures can be implemented.
Early detection of these problems helps prevent catastrophic failures, reduce maintenance costs, and optimize turbine performance.
The Borescope Inspection Process
- Preparation: Before the inspection, each stage of the blade assembly is sequentially marked, removed, and arranged. Technicians determine the precise inspection port for borescope insertion.
- Insertion and Navigation: The engineer carefully inserts the Mitcorp X2000 endoscope with a 2.8 mm probe into the blades, maneuvering through the complex internal structure.
- Visual Inspection and Documentation: The X2000’s ample brightness and 120-degree low-distortion wide-angle lens capture high-resolution images, providing crucial references for evaluating key components.
- Analysis and Reporting: The collected data is analyzed, and a report is generated to recommend necessary maintenance actions.
Below are images captured during borescope inspections of gas turbines, showcasing real-life examples of internal component assessments.
Conclusion
Borescope inspections are a vital part of gas turbine maintenance, providing a reliable and non-invasive way to assess internal components. With advancements in imaging technology, these inspections have become even more effective in preventing failures and ensuring the longevity of turbines.