New player for servicing, upgrading Siemens gas turbines packs punch

A defining moment for gas-turbine users occurred during the Siemens F-class roundtable at the recent CTOTF Fall Turbine Forum in Rancho Mirage, Calif, when Rich Wallen of Oglethorpe Power Corp, who chairs the session, introduced a company new to the market of services, parts, mods, and upgrades for Siemens units: GE Power. Readers may recall that the GE acquisition of Alstom included PSM which was then sold to Ansaldo Energia to satisfy regulatory requirements. In the process, GE retained intellectual property from PSM on non-GE technology, which brings us to this point.

Jim Masso, GE’s engineering leader for non-OEM GTs, stressed two goals for this business unit:

      • Operating intervals of more than 32,000 hours for F-class units.

      • Total combined-cycle plant support for equipment and remote monitoring.

Is GE serious? Absolutely: The company was said to be investing significantly in non-OEM products and services—one of the company’s largest investment areas over the next several years. Today, GE has over 300 engineers dedicated to non-OEM engines. It is now monitoring remotely six 501F units and will add eight more in 2017.

Looking ahead, GE plans to offer in 2018 a 501F Advanced Gas Path (AGP) upgrade solution similar to the one it has for the 7FA. The company already has nailed down casting slots to ensure a well-established supply chain. New parts for the 501F hot gas path (HGP) will be available next year.

Beyond 32k. For first-stage 501FD3 turbine blades, GE believes in equiaxed GTD 141+, a proven and improved alloy over conventionally cast Inconel 738. It is a more capable and easier-to-repair alloy than most directionally solidified (DS) and single-crystal materials, one of the company’s experts told the editors. Plus, it doubles the creep life of the part. Additionally, improved cooling geometry will help extend intervals beyond 32,000 hours.

The speaker said the company is moving away from DS to equiaxed metallurgy even on H machines. This is sure to impact the casting supply chain.

Getting to 32k intervals with HGP hardware is not really the challenge, attendees were told. The proverbial fly-in-the-ointment comes from an auxiliaries’ perspective. According to Masso, with the equipment currently installed in the fleet, the 32k interval is not likely achievable. Upgrades are necessary to make gas control valves, compressor bleed valves, etc, more robust.

Parts health management. LifeSight, a wire-free strain/creep sensor permanently affixed to the surfaces of parts, such as compressor blades, indicates strain beneath the sensor. Data are retained for trending. Attendees were urged to investigate this new offering given increasing emphasis on the digital transformation of electricity and the need for viable diagnostics/prognostics solutions.

Generators. GE’s Ron Cox discussed two options for Aeropac spark-erosion inspections: alpha coefficient with visual inspection and PD measurement. Erosion in the slot causing increased vibration is an issue in this fleet. GE does not use conductive shims for rewinds, it removes them, and employs a patented conductive taping solution that has been successful in eliminating vibration problems.

How to learn more. Masso and his team are on the agenda for their first 501F User Group meeting, Feb 19-23, 2017, at the Peppermill in Reno, Nev. Presentation topics include hardware upgrades, parts health management, rotor life extension, and Aeropac rewinds.

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