Hydrogen Seal Upgrades

image credit: MD&A
Jay Eldridge's picture
Vice President Sales & Marketing, MD&A

Bachelor of Science (BS) in Mechanical Engineering with a Mathematics Minor from Union College.  28 years’ experience working in the power generation industry.  Almost 17 of those years were...

  • Member since 2013
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  • Jan 12, 2022

Mechanical Dynamics & Analysis (MD&A) upgraded a customer’s hydrogen seals for a 7FH2 generator located in Colombia.

Many units in the combined cycle setup, which can be comprised of two MS7001FA gas turbines and a D11 steam turbine, are also equipped with 7FH2 generators. Often, these machines have unbolted babbitted hydrogen seals. If there’s any contamination of the oil or improper assembly, those conditions may cause the unbolted seals to tilt, which could lead to a hydrogen leakage and oil ingress into the generator.

The OEM recommendation is to upgrade the hydrogen seals to a bolted style which involves replacing the housings. MD&A offers a more cost-effective option to modify the existing housing to accept bolted seals.


The customer requested an upgrade of their existing unbolted hydrogen seals to a bolted design for two of the two generators.

MD&A supplied the two casings with a bolted style along with the upgraded hydrogen seals and all the hardware required. We also supplied a spare set of D11 valve parts and hardware.

For upcoming maintenance, MD&A also supplied one set of 7FA refurbished third-stage hot section parts (including buckets, nozzles, and shrouds).

Our Bearings, Seals & Hydraulics division stocks a large number of hydrogen seals at our Euclid, OH facility, and we can service any size machine. If we don’t have the seals in stock, our skilled technicians can fabricate them using materials we have in the shop.

When a customer orders a set of hydrogen seals from us by part number, we don’t just manufacture the seals to the standard original size. Instead, we always have a dialogue with the customer to learn what their journal size is and what their housing cavity thickness might be. Then we custom size the seals to fit properly. Some of our craftsmen have been doing hydrogen seals for 20-plus years, so they are well-seasoned and trained in doing the work.

Since 1984, MD&A Bearings, Seals & Hydraulics Division has designed, manufactured, retrofitted, and repaired hydrogen seal rings to correct operational issues such as excessive oil flow, excessive hydrogen consumption, and electrolysis. We have also developed a level of service designed to substantially reduce the manpower traditionally associated with the field ­fitting of critical seal assemblies. Call MD&A today at +1 (518) 399-3616.

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Bob Meinetz's picture
Bob Meinetz on Jan 12, 2022

Jay, having effective and durable hydrogen seals in turbines is certainly an important consideration. In 2020, Diablo Canyon (nuclear) Power Plant was shut down for months due to leaking hydrogen from a seal. Though seal replacement would have been a relatively routine affair, after reassembly technicians discovered a warren of rabbits had occupied a chamber in the turbine, and had to take it apart again (anecdotal/unconfirmed report).

Jay Eldridge's picture
Thank Jay for the Post!
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