Observations indicated galling in root serrations and seal pin surfaces, as well as the presence of two distinct casting houses to produce the row of buckets.<\/p>\n
![\"gas](\"https:\/\/www.mdaturbines.com\/wp-content\/uploads\/2018\/08\/4-e1534252980655-226x300.png\" "\\"gas")
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Scope of work included a visual inspection, dimensional measurements, and an x-ray inspection. Also included were a microstructural assessment, high-temperature mechanical properties testing, assessment of material condition at multiple locations, heat treatment of specimens to demonstrate the effects of repairs, and high-temperature mechanical property testing performed post-heat treatment.<\/p>\n
Inspections showed that the manufacturer\u2019s heat treatment had not achieved full solutioning. All blades also displayed a two-phase gamma prime structure within each grain, indicating that the previous repair heat treatments were not optimized to achieve a good structure. In addition, all three blades had surface oxidation and depletion. Even so, the components all were deemed repairable.<\/p>\n
![\"9FA](\"https:\/\/www.mdaturbines.com\/wp-content\/uploads\/2018\/08\/5-300x142.png\")
Additional repair work included grit blasting and polishing the gas path surfaces to remove an oxide layer, a complete X-ray inspection, and HVOF coating and diffusion to reduce surface degradation.<\/p>\n
MD&A\u2019s Repair heat treatment was applied to several samples from the test blades, then evaluated to determine the material\u2019s response to these heat treatments. The material responded well to the heat treatments on all three blades. The gamma prime transformed to a more cuboidal morphology, which provides for improved component creep life.<\/p>\n These third-stage blades were evaluated and subsequently determined to be candidates for a Lifetime Extension (LTE) repair. The 9FA 3rd stage blades\u2019 lives were extended to 120K FFH.<\/p>\n MD&A\u2019s available Gas Turbine services range from full turnkey major inspections to rotor unstacking, gas turbine alignment, and control services. MD&A is a global full-service OEM alternative for services, parts, and repairs.<\/p>\n Call our MD&A San Antonio Service Center, or our Gas Turbine Parts Service Facility today at +1 (210) 256-5000.<\/p>\n Also, be sure to sign up for our MD&A Insight e-newsletter<\/a> delivered quarterly. Get our turbine-generator expert\u2019s case studies and tips! Fill in the sign-up form and SUBSCRIBE!<\/p>\n![\"Microstructure,](\"https:\/\/www.mdaturbines.com\/wp-content\/uploads\/2018\/08\/6-300x208.png\")