Mechanical Dynamics & Analysis (MD&A) can extend the service life of gas turbine components whose OEM service limit has passed or whose configuration is no longer suitable to operate. Significant savings can be realized by opting for lower-cost repaired spares instead of new parts.
Elevated temperatures take a big toll on gas turbine components. Repair enhancements can extend a part’s life by slowing its degradation and extending its usable service life.
Formerly PW Powers Systems’ IGT division, the MD&A San Antonio Texas Service Center team have years of experience evaluating the life-limiting factors for gas turbine vanes and blades. Such factors include cracks, corrosion, wall thickness, and material condition. Most crack limiting locations are found at the platform or shroud transition. Smaller percentages occur at the blade tip, the blade airfoil, or the root. Vane limiting factors are usually related to the wall thickness and material condition.
Platform degradation can be reduced in many ways: by operating in base load only ( although dispatch conditions may prevent that from being a practical solution), by pursuing a robust platform weld repair program, by improving the integrity of the platform coating, and by making platform improvements.
Thermal mechanical fatigue cracks will eventually lead to platform failure. Design modifications often are required, incorporating a robust repair procedure. The life cycle enhancement process used by our experts exceeds OEM platform properties.
Our experts at the San Antonio Service Center combine years of experience with state-of-the-art equipment to deliver exactly the right solutions to your specific set of parts!
9FA 3rd Stage Blade Extended to 120,000 FFH
Three 9FA 3rd stage blades were received by our San Antonio facility where they underwent detailed inspections, including microstructural assessment and high-temperature testing.
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.
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.
Inspections showed that the manufacturer’s 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.
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.
MD&A’s Repair heat treatment was applied to several samples from the test blades, then evaluated to determine the material’s 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.
These third-stage blades were evaluated and subsequently determined to be candidates for a Lifetime Extension (LTE) repair. The 9FA 3rd stage blades’ lives were extended to 120K FFH.
MD&A’s 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.
Call our MD&A San Antonio Service Center, or our Gas Turbine Parts Service Facility today at +1 (210) 256-5000.
Also, be sure to sign up for our MD&A Insight e-newsletter delivered quarterly. Get our turbine-generator expert’s case studies and tips! Fill in the sign-up form and SUBSCRIBE!
Proprietary Notice: WARNING – This document is the property of MD&A. You may not possess, use, copy or distribute this document or any information in it for any purpose, including without limitation to design, manufacture or repair parts, or obtain FAA or other government approval to do so, without MD&A express written permission. Neither receipt nor possession of this document alone, from any source, constitutes such permission. Possession, use, copying or disclosure by anyone without MD&A express written permission is not authorized and may result in criminal and/or civil liability. EAR commercial/Civil or Dual- Use Notice: WARNING — This document contains technical data the export of which is or may be restricted by the Export Administration Act and the Export Administration Regulations (EAR), 15 C.F.R. parts 730-774. Diversion contrary to U.S. law is prohibited. The export, re-export, transfer or re-transfer of this technical data to any other company, entity, person, or destination, or for any use or purpose other than that for which the technical data was originally provided by MD&A, is prohibited without prior written approval from MD&A and authorization under applicable export control laws. EAR Export Classification: EAR 99
© 2021 Mechanical Dynamics & Analysis LLC. All Rights Reserved
