In-situ extraction of a migrating 7EA S-12 shim saves owner more than $400k

By Team-CCJ | October 26, 2020 | 0 Comments

It was only a few years ago that owner/operators of GE E- and F-class gas turbines learned technicians from Advanced Turbine Support LLC could extract or blend shims in the first three compressor stages in-situ—no case removal necessary. That was a big deal because shims found protruding into the compressor air stream during a borescope inspection could be dealt with immediately, preventing an offending shim from possibly going downstream and damaging rotating and stator blades.

Update: A week ago, Mike Hoogsteden, Advanced Turbine Support’s director of field services, called to say the company’s technicians had removed in-situ a protruding shim in the 12th stage of a 7EA, saving the owner the more than $400k it would have cost to extract the shim had case removal been required.

It was perfect timing for this industry-first accomplishment given the 7EA Users Group meeting convenes online about two weeks (October 20). Register now (users only) at no cost and come up to speed on developments and experiences in the 7B-EA fleet since the 2019 conference. The virtual venue under the Power Users umbrella is certain to push attendance to new heights and share information valuable in decision-making.


Hoogsteden added that the protruding shim was located above the right case break (photos) and that the peaking unit had recorded about 8500 service hours and nearly 700 starts when the inspection was conducted. He suggested that O&M personnel new to the GE E-class fleet become familiar with TIL-1562, “E- and F-Class Shim Migration and Loss,” issued in January 2007. To dig deeper into the subject, consult the 7EA Users Group library on the Power Users website and meeting reports available in CCJ’s searchable archives at

Advanced Turbine Support developed, patented, tested, and proved a few years ago the tooling that today allows—depending on rotor stacking—in-situ blending of compressor blades and stator vanes as far back as Stage 12 with favorable access.

The blends can be analyzed by engineering to determine any associated risks both before and after the work is done. Hoogsteden says his company recommends attempting in-situ blends on rotating blades and stationary vanes when engineering analysis confirms such repairs are preferable over immediate unit disassembly.

Concerning shim migration, he adds that once a shim has migrated to approximately 50% of its height and is protruding into the air stream, the OEM no longer considers this a low-to-medium risk condition and it should be removed or blended flush.

UPDATE: PowerUsers Combined Conference going digital (CCUG, STUG, GUG, PPCUG)

By Team-CCJ | July 12, 2020 | 0 Comments

Covid-19 has wreaked havoc on the CCGT industry’s user conferences and there is no end in sight. PowerUsers, the umbrella organization presiding over six of the industry’s most robust and influential user groups, decided early last week to forego a face-to-face meeting of their Combined Conference this year.

The conference is home to the Combined Cycle, Steam Turbine, Generator, and Powerplant Controls Users Groups. The groups are opting for an all-digital, screen-to-screen series of webinar sessions to disseminate valuable information to owner/operators all over the globe.

Once again, PowerUsers will team up with COMBINED CYCLE Journal to bring this year’s content to your desktop or mobile device, as we have already during the 7F Users Group 2020 Digital Conference, where nearly 600 users are accessing a variety of technical content critical to their operations, both live and on-demand. Presentations, contact information, forum interaction, and interactive Q&A are all at all registrants’ fingertips unlike ever before.

This 2020 Digital Combined Conference will feature many of the same opportunities for vendors to connect with users during this challenging time:

    • OEM and OOEM extended technical presentations.
    • Live special technical presentations.
    • Recorded technical presentations.
    • Virtual vendor fairs with live video feeds (all in one platform).
    • Post-session, deep-dive roundtables.
    • Access to the fastest growing customer demographic: the virtual user group conference attendee.

Details will be emerging in the coming weeks. Email conference coordinator Sheila Vashi,, for preliminary updates and to make sure you are a part of all official communications forthcoming. Be safe and see you on-screen.

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