Breaking the Ice: NNSY and SRF-JRMC Partner for First-of-its-Kind Freeze Seal Training

In a milestone event for international collaboration and maintenance innovation, Norfolk Naval Shipyard (NNSY) recently hosted a team from the U.S. Pacific Fleet’s Ship Repair Facility and Japan Regional Maintenance Center (SRF-JRMC) for a groundbreaking training evolution.

From May 11-15, an 11-person delegation from Yokosuka, Japan—including nine Japanese contract workers—visited NNSY to observe and participate in freeze seal mock-ups. Freeze seals isolate piping system sections by freezing fluid inside and enabling needed maintenance to be performed. What started as a planned demonstration quickly evolved into a masterclass in adaptability, resulting in corporate firsts and an unforgettable moment of cross-cultural celebration.

The Roots of the Operation

The initiative began in June 2025, when SRF-JRMC’s Process Improvement Division reached out to NNSY looking for guidance. SRF-JRMC was exploring the establishment of a non-nuclear freeze seal program specifically for conventionally powered surface ships.

NNSY’s Piping Group (Code 960) along with the Reactor Engineering Division (Code 2310) stepped up, sharing years of NNSY’s research, lessons learned, and cost-estimate comparisons. This digital exchange laid the groundwork for the Japanese team to travel across the globe to learn directly from Norfolk’s deckplate experts.

Corporate Firsts & The Pivot

The original plan for the visit was to teach the Japanese group liquid carbon dioxide (LCO2) freeze seals, through both demonstrations and hands-on training opportunities, with a brief introduction to other methods like liquid nitrogen (LN2), vortex, and Freon units if time permitted.

During the first half of the week, the Norfolk team executed two highly successful LCO2 mock-ups on an eight-inch pipe completely full of seawater. Because seawater requires significantly more thermodynamic energy to freeze solid compared to freshwater, achieving this seal was a monumental success and a first-time achievement for Portfolio Acquisition Executive—Industrial Operations (PAE-IO). Once the SRF-JRMC team successfully grasped the mechanics of the LCO2 process, its members realized they had an opportunity to maximize their trip. They asked the NNSY team if they could pivot the hands-on training to perform an LN2 freeze seal instead, as LN2 was heavily being considered for large-diameter piping back in Yokosuka. An LN2 freeze seal had not been previously attempted on an eight-inch saltwater pipe by any group within the Navy’s shipyards and maintenance facilities.

Embracing the shipyard’s spirit of innovation and flexibility, NNSY agreed. The team seamlessly shifted gears and transitioned the mock-up to an LN2 evolution.

"NNSY was going to do everything possible to make their trip a success, and we were glad to make that happen," said Code 960 Superintendent Chris Gallihugh.

A Moment of Celebration The LN2 freeze seal process is highly technical and requires strict safety protocols, especially on large piping. The combined US-Japan team worked meticulously to establish an “ice plug” that acts as a barrier and allows maintenance work to be performed.

The defining moment of the week arrived during the final validation. Once the LN2 freeze was fully obtained and the hydrostatic pressure test held perfectly, the typically reserved Japanese group erupted into an outburst of cheering and high-fives.

It was a powerful reminder of how much this capability meant to the Yokosuka team, breaking through cultural barriers and language differences in a shared moment of triumph.

Strategic Return on Investment

The reason behind the cheering is tied directly to fleet readiness. While NNSY has long utilized freeze seals on the nuclear side—and recently on non-nuclear systems for aircraft carriers like USS Harry S. Truman (CVN 75) and USS George Washington (CVN 73)—the goal of this partnership was to transition that high-level expertise to the conventionally powered surface fleet.

SRF-JRMC identified Guided Missile Destroyers (DDGs), Cruisers (CGs), and Amphibious Command Ships (LCCs) as the primary beneficiaries of this new capability. Without a freeze seal option, these ships often have to live with mechanical deficiencies until a massive, system-wide drain-down can be scheduled.

"If they have the capability and can freeze it without a long lead time, they can get a lot more maintenance done during shorter in-port periods. So they don't have to live with deficiencies for so long until they can drain it," explained Senior Nuclear Engineer Jeremy Owen (NNSY) during the cross-shipyard discussion."

Owen pointed to a recent NNSY success as proof: "For the eight-inch chill water [freeze seal] we did, it was going to be three years before they had a maintenance period they could have put the work into. Plus, we are proving out we can do these freezes with flow. So that's a hurdle that doesn't have to be jumped over on a short turnaround job."

NNSY recently added a mock-up area that will be used for research and development and mock-up of potentially challenging freeze seals.

"Having a ready-to-go mock-up will typically save eight to 12 weeks in execution versus starting from scratch," Owen added.

Empowering the Deckplate

While the technical achievements were historic, the impact on the NNSY personnel who led the training was equally profound.

"This whole experience was a very humbling one," said Kimberly Barnes, an NNSY instructor who helped lead the mock-up. "When I first became an instructor, I was doubting how far I could go, but now seeing myself train others on an international level speaks volumes for me. I no longer have doubts about how far we as a shipyard can go."

"Those guys were awesome to work with," remarked Freeze Seal Instructor Stanley Bialk.

"They cheered and high-fived when the freeze seal passed hydro, that’s something you don’t see every day," said Nuclear Test Supervisor Lakil Mayes.

"This trip was a great opportunity for our Japanese [Master Labor Agreement] workforce to learn from the Norfolk Naval Shipyard team and get hands-on experience with freeze seals. Challenges with fire main isolation are endemic across the waterfront. Embracing innovative solutions like this directly aligns with the Navy’s 'Get Real, Get Better' initiative and can provide us another valuable tool to keep the fleet mission ready," said Lt. Cmdr. John Langreck, SRF-JRMC deputy project superintendent.

By taking the initiative to research, test, and share this unprecedented eight-inch saltwater freeze seal process, NNSY has not only strengthened its partnership with the U.S. Pacific Fleet but also permanently thawed weeks—and sometimes years—of potential downtime for future ship maintenance availabilities.