Masahiko Onda

OEM’s Approach to Maintain High Reliability of Hot Gas Path Parts

The reliability of gas turbine (GT) Hot Gas Path components requires both design and metallurgical expertise. There are numerous repair facilities around the world with general metallurgical expertise. However, the maintenance process can be noticeably improved through a feedback approach that incorporates the original part design know-how and the fleet wide experience gathered from operational data. A lot of users apply daily start-stop cycles so these peaking operations will impose more severe duties on the hot gas path parts (HGPPs). For this reason, we have achieved high GT reliability, low fall out rate, and improved repair processes utilizing our in-house verification plant (combined power plant of G class GT). For service units, the Remote Monitoring concept [1] was developed to provide an extra level of protection and diagnostics for power generation equipment and it has also facilitated correlation between HGPPs distress and operational profiles. The use of historical operating data, including number of cycles, trips, and rapid load changes can reveal valuable information on the HGPPs distress and assist repair process improvement. Fleet database can give lots of feedback on the reliability and durability of the repaired components. This paper describes our own process of improving HGPP design and feedback to the maintenance. This process includes analysis of thermal barrier coating (TBC) degradation, careful application of life assessment techniques on substrate metallurgy, and analysis of operational data to improve design and repair techniques for increasing fleet availability.Copyright