F-class gas turbines are the most technologically advanced gas turbines in general commercial service throughout the world. Over the next 15 years in North America and Europe alone, approximately 180 F-class gas turbine rotors will reach the rotor-life inspection outage requiring a complete disassembly, inspection, life assessment and repair of the rotor. With its ability to repair F-class rotors, Dresser-Rand TTS (D-R TTS) is among the elite shops worldwide that are capable of dealing with these high-tech parts (see Sidebar).
“To successfully repair the high-tech designs of F-class rotors, a fully equipped world-class facility complete with engineering capability and top-notch technology are all required,” says Dan Levin, General Manager of Dresser-Rand Strategic Business Units for Gimpel® Valves, Control Systems and Turbine Technology Services. “Our expanded repair facility in Houston has the capabilities needed to help clients better manage their rotors to meet or exceed the original design lives of those components.”
The new shop adds 24,000 square feet for an additional high bay rotor facility, with a 75-ton crane and 50 feet under the hook, sufficient for F-class rotors up to Frame 9. It can service all brands of industrial gas and steam turbine rotors with blade replacement, unstacking and restacking, balancing and non-destructive testing. The site can also execute first-stage bucket and nozzle repairs specifically for F-class equipment.
The site's repair solutions are supported by machining, ultrasonic cleaning and vacuum heat-treating capabilities, braze repair, sonic nozzle and high-volume flow testing and HVOF and air plasma coating. D-R TTS also offers metallurgical evaluation, failure-analysis material engineering, ASNT Level III certified inspection, factory-trained and factory-certified tool calibration, and has more than 35 combined years of coating development experience. These in-house services aim to reduce repair cycle times and assure better quality control. The facility is ISO 9001:2008 certified, providing clients with further assurance that their utility gas and steam turbine repairs will be performed in compliance with the highest level of international quality control standards. According to the company, the operations are supported by a highly skilled workforce that brings vast capabilities with respect to quality, scheduled deliveries and cost effectiveness.
“Combined with our world-class component repair and expert engineering staff, the addition of F-class rotor repair in Houston provides an important service alternative to the OEM for North American operators,” Levin notes. “Moreover, the company’s capabilities allow it to perform an expanded risk assessment for operation beyond the rotor-life outage.”
Gas turbine rotors require a life assessment after a predetermined combination of starts and/or operating hours. Dresser-Rand TTS has a proprietary rotor-life assessment (RLA) program that helps clients evaluate their equipment based upon actual operating conditions (instead of generalized fleet limits), and thus make sound, fact-based decisions on a rotor’s suitability for continued operation.
This RLA program includes a comprehensive disassembly and inspection of the rotor, combined with a detailed engineering analysis of critical components. According to the company, it’s this proprietary engineering analysis that differentiates the D-R TTS program from others. Non-destructive inspection alone only identifies existing defects; when combined with a detailed engineering analysis, a complete picture of the true
predicated risk of continued operation is available and takes into account such factors as creep, fatigue and/or corrosion. The D-R TTS RLA program forms the basis of successful continued operation through a combination of inspections, detailed engineering analyses and repair and parts solutions that can result in considerable savings compared to the cost of replacing a unit.
In addition to upgrading its Houston facility, Dresser-Rand is expanding its industrial gas and steam turbine repair capabilities worldwide. Last year, it invested in new facilities in Europe and Asia. The Peterborough, UK, site includes 18,000 square feet (1670 square meters) dedicated to refurbishment of GE and Siemens-Westinghouse frame turbines. To better serve the Asian and Australian markets, the company upgraded its Cilegon, Indonesia, repair shop into another D-R TTS Center of Excellence by adding a dedicated IGT facility that incorporates a new rotor shop with full inspection, disassembly and repair capabilities. MT
In 2010, Dresser-Rand acquired the assets of Leading Edge Turbine Technologies, a specialist in the repair of industrial gas turbine combustion, stationary and rotating components for most major gas-turbine OEM models and frame sizes. The company’s credentials also included a large, on-site rotor repair shop that provided services for all brands of turbomachinery (from scheduled maintenance to emergency rush services). Leveraging Dresser-Rand's field-service capabilities with Leading Edge's engineered-repair strength, the new venture, now called D-R TTS, offers bundled services for all steam and industrial gas turbines. The 88,000-sq.-ft. D-R TTS “one-stop shop” in Houston includes complete welding, machining and mechanical capabilities to service or repair all types of rotating equipment.