A fatal liquid nitrogen release at a poultry processing facility occurred because there was a single point of failure built into the freezer room and employees weren’t trained to identify the hazard.
The U.S. Chemical Safety and Hazard Investigation Board (CSB) found that the incident that killed six workers in 2021 at the Foundation Food Group facility in Gainesville, Georgia was also due to a lack of process safety management policies.
Workers told to take break while maintenance worked on freezer
On Jan. 28, 2021 at 8:20 a.m., Line 4 of Foundation’s product packaging department was shut down when workers noticed that the chicken products weren’t fully frozen as they were going through the flash freeze process.
The Line 4 freezer used liquid nitrogen to quickly freeze chicken products before they were packaged for shipment. It was designed and owned by Messer LLC and leased to Foundation. Messer personnel had been onsite for several days before the current failure, trying to figure out why the freezer continued to fail.
A line packaging supervisor told the Line 4 workers to take a break while Foundation maintenance employees attempted to fix the ongoing problem with the immersion freezer.
Freezer wasn’t shut down, safety switches were bypassed
The Foundation maintenance employees began working without shutting down the freezer and with the transition box door and immersion freezer lid safety switches intentionally bypassed. The safety switches were meant to shut off the liquid nitrogen supply and increase the speed of the nitrogen exhaust fans when the doors were opened to prevent accidental liquid nitrogen releases.
At some point during the maintenance process, the immersion freezer’s bubbler tube somehow became bent, preventing the liquid nitrogen level control system from working properly. This caused the liquid nitrogen level to increase and then overflow from the freezer, filling the room with vaporized nitrogen which displaced the oxygen in the air.
6 dead after entering freezer room to investigate situation
Twenty minutes later, the Line 4 employees returned from their break. Several of them noticed a white fog from the nitrogen release when they looked through a window into the freezer room, but they didn’t realize there was a problem.
One of the workers also realized that she hadn’t seen the supervisor in more than an hour and began to look for him. She crawled through an elevated opening where the line ran through the freezer room and saw the white fog as well as one of the maintenance workers who was lying unresponsive on the floor.
The worker crawled back out of the elevated opening and told her co-workers what she’d seen. They decided to inform the Line 1 packaging supervisor what happened. This led to a series of events that saw at least 14 employees, both supervisors and workers, investigating the freezer room. Six of those who entered the room died from asphyxiation injuries and four others were seriously injured.
Following the incident, Foundation sued its insurance company for damages of roughly $1.7 million while Messer reported losses of its own of roughly $245,000.
CSB investigators found that the bubbler tube – which was likely bent at some point when maintenance tried to fix the immersion freezer – was the main cause of the incident. The incident was made more severe by Foundation’s inadequate emergency preparedness.
Overall, the CSB found five key safety issues that led to the incident, including the following:
1. Bubbler tube was a ‘single point of failure’
The design of the immersion freezer included the bubbler tube, which measured liquid nitrogen levels inside the freezer.
When the device was bent it could no longer measure and control the freezer’s liquid nitrogen level, causing an overflow which filled the room with vaporized nitrogen.
The CSB said that this design was vulnerable to a single point of failure because when the bubbler tube became bent there was nothing else to prevent a liquid nitrogen release. Investigators found that Messer’s design team didn’t adequately consider the consequences of a bubbler tube failure and didn’t put appropriate safeguards in place to mitigate a failure.
Further, Messer personnel didn’t notice a manufacturing defect involving a missing clamp that increased the potential for the bubbler tube to get bent.
2. Lack of atmospheric monitoring and alarm systems
Despite “abundant industry guidance on the importance of atmospheric monitoring when the potential for hazardous atmospheres exists” Foundation used no such equipment in the freezer room.
That meant there was no equipment installed that would detect an oxygen-deficient atmosphere, shut off the liquid nitrogen supply and notify employees to evacuate the area.
3. Failure to adequately prepare workers for emergencies
Foundation’s workers and supervisors lacked knowledge regarding the hazards of nitrogen and were unable to recognize any of the signs of an oxygen-deficient atmosphere. They also weren’t equipped with, or trained how to use, PPE that would have allowed safe entry into such an atmosphere.
That’s because Foundation “did not inform, train, equip, drill or otherwise prepare its workforce for a release of liquid nitrogen,” according to the CSB. Foundation also failed to “proactively interact” with local emergency response agencies prior to the incident even though the company relied on them to handle emergencies at this facility.
All of this resulted in a chain reaction of employees discovering deceased employees in the oxygen-deficient atmosphere who in turn succumbed to the atmosphere themselves because they weren’t trained to identify the hazards. To make matters worse, when emergency responders first arrived they also weren’t fully aware of the hazards, which took time away from their response efforts.
4. No requirement to have process safety management systems
Once again, despite “robust” industry guidance on process safety management (PSM) systems, Foundation had no documented PSM policy and wasn’t required by law to implement one.
Along with not having a PSM policy, Foundation also:
- allowed the job position responsible for safety management to be vacant for more than a year prior to the incident
- didn’t evaluate process hazards associated with the freezer
- lacked written procedures and management of change processes, and
- didn’t train employees or management regarding the asphyxiation hazards of liquid nitrogen.
Because the company didn’t have PSM procedures in place, and wasn’t required to, it didn’t use systems and practices that could have either prevented or mitigated the severity of a liquid nitrogen release.
5. Inadequate product stewardship
Messer was the designer and owner of the immersion freezer and other liquid nitrogen-related equipment at the Foundation facility. CSB investigators found that the company had the knowledge, experience and policies needed for effective product stewardship but failed to apply it to all of the equipment it leased to Foundation.
Instead, Messer focused primarily on the bulk storage tanks it leased to Foundation and failed to apply stewardship practices to the Line 4 freezer process. This occurred despite the fact that Messer had identified problems with Foundation’s safety practices and non-conformance with industry guidance.
