Just having a safety procedure in place is not enough. Procedures must be followed to be effective; failing to do so can result in fatal consequences, as a recent Mine Safety and Health (MSHA) investigation illustrates.

MSHA investigators were called to the Freeport-McMoRan Morenci mine in Greenlee County, Arizona, this past September to investigate a fatality involving a contract welder who died while working with argon gas in a confined space.

The contract company, PVB Fabrications, had a confined space safety procedure created jointly with the mine operator, but much of it had been ignored, leading to the welder’s death.

Argon Gas Used to Purge Ambient Air

On the day of the incident, two welders began work on a 30-inch pipe by placing a dam inside the pipe on each side of the joint and then filling that space with argon gas to purge the ambient air.

During the welding process, the two welders noticed “sugar” on the weld, indicating that the argon gas didn’t fully purge the ambient air, resulting in contamination. One welder exchanged the argon gas bottle with a new one, meaning they had to wait for the purge to finish before work could continue.

Asphyxiated after Entering Pipe

At one point, the welder noticed his partner’s hard hat at the end of the pipe and went to check on him. The welder called out with no response. Using a flashlight, he saw his coworker about 40 feet inside the pipe. After no response from the downed worker, they called the mine’s emergency response team.

The emergency response team arrived on the scene and began their rescue efforts. Once pulled from the pipe, the welder was found to have no pulse, and emergency responders couldn’t resuscitate him. He was pronounced dead at a local hospital an hour later.

MSHA investigators found that the welder likely entered the pipe to check on or reposition the argon gas dam, which led to his asphyxiation due to the argon gas, which displaced the oxygen in the confined space. No warning signs were posted regarding the confined space and its oxygen-deficient atmosphere, and no physical barriers to prevent workers from entering the pipe.

Entry Procedure in Place, Wasn’t Followed

PVB welders didn’t enter pipes regularly, but when they did, there was a confined space entry procedure established jointly by the mine and the contract company, which stated the:

  • PVB welder must notify their supervisor,
  • Supervisor must obtain a confined space entry permit,
  • Supervisor must request and obtain ambient gas detection equipment from the mine operator, and
  • Welder must wear safety belts and lines, which an additional worker could monitor and adjust as necessary.

In this case, there was no permit and no request for ambient gas detection equipment.

Company Updated Training on Procedure

MSHA investigators found that PVB’s Hazard Communication program didn’t include argon gas and that the company failed to adequately train its welding crews and supervisors on the safe use of argon gas in confined spaces.

PVB has since updated its program to include argon gas. The company also developed more thorough programs and training to:

  • Provide warning signs and barricades for workers entering confined spaces,
  • Verify a respirable atmosphere before entering confined spaces, and
  • Ensure workers knew and practiced the safety procedures for entering a confined space, including wearing safety belts and lines and having an additional worker to monitor and adjust lines as needed.

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About the Author

Jon Knight

Jon Knight leads the NASP Team’s media creation department. He has been involved with workplace safety training since 2017 with a focus on course creation. He also provides video production and voiceovers for NASP content.
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