"Local Fire Chief said his team simply vacated the plant immediately...."

The Aluminium Plant Safety Blog has posted incidents where unbeknownst to company management a fire suppression system was installed and if activated that should have never been. All too often we will tour plants that have fire sprinklers above a container of molten metal, or in a storage area that contains fuel sources that should be extinguished with a Class D fire extinguisher and not water. Here is a recent incident that may have been prevent if the fire suppression system had not been able to be activated.

An explosion during an auto parts plant fire that ultimately stopped production of the Ford F-150 was so violent that it threw a worker through the air into a door jamb. Vehicles in the parking lot caught fire and were damaged by flying debris. A fire "detector did not alert occupants."

The explosion and a subsequent blast early the morning of May 2018 at a magnesium factory in the USA occurred because the fire suppression system at the plant added water to molten magnesium. Experts said that is like arming a bomb.

Firefighters called to the factory went to the maintenance room "and looked at the bottom of the scrap conveyor (where) we saw a white glow in the tunnel. We exited the plant at that time,” the local Fire Chief wrote in his official report.

The report, made public Monday, said the plant sustained an estimated $8 million in damage. It makes highly specialized auto parts used in Ford F-Series trucks and several other vehicles. General Motors, Fiat Chrysler, Mercedes and Ford were affected, with F-Series production fully shut down for eight days.

The State Occupational Health and Safety Administration is investigating the incident.

On May 2, the fire report said, “We went to the sprinkler system … and found water was flowing through the pipes … We saw the damage from the first explosion on the west side of the building. I called for an engine to come to my location to extinguish some fire in the mechanical room where no magnesium was. We started to get the engine ready, I sent a firefighter to hook to hydrant. This is when the second explosion occurred.”

It was 2:01 a.m.

“After the second explosion it was reported that there were two employees injured, one by debris that was ejected from the plant and the other employee was injured by the blast of the explosion at the south end of the plant by the scrap tunnel ... We did not try to extinguish any fires at the plant because of the molten mag in the area. The roof of the re-melt building caught fire and burned, there were three machines with two crucibles each with ten thousand pounds of molten mag in them.”

An initial cause of the fire has not been determined.

“With the destruction that the second and third explosions caused, it was impossible to find what caused the first explosion,” local fire department told the local news media. “The second and third explosions were the result of water and molten magnesium. That was observed by myself and employees of the plant after the first alarm was sounded.”

Another local Fire Capt., a team leader for the County Hazardous Materials Response Team, said firefighters would usually use Class D extinguishers on magnesium or other metal fires because the powder would smother the oxygen of a fire and eliminate a reaction.

“When you’re adding little drips of water onto a magnesium fire, it’s exploding and exploding, and all that liquid melting metal then gets onto combustible materials like wood, fabric, carpeting, walls. And then that would start on fire,” said the local fire department chief.

The worker was thrown through the room because explosion causes a shock wave.

“That’s how a bomb works,” the local fire chief said. “And this is very typical of magnesium. Once the magnesium is ignited, it explodes when water added to it. It’s going to be a very dynamic incident. A very dangerous incident for firefighters and the surrounding community. They were lucky there were no fatalities.”

  

Local Fire Chief said his team simply vacated the plant immediately.

“We didn’t fight any fire up there. Everything happened too quick," he said. “The only thing we did is set the ladder truck up and look at the top of the building. If there’s any mag fires, we don’t fight them. We let people at the shop do it. But this was beyond their control. They simply evacuated.”

We pray for the injured workers. We hope they recover fully from the injuries. The photos above show the aftermath of these explosions and fires. Luckily no one was killed. We commend all the first responders who knew what to do when a magnesium fire broke out.

It is our opinion that the company did not know that the fire sprinkler system worked in that plant. Regardless, we feel confident that when this factory is rebuilt no new fire sprinklers will be installed anywhere near molten magnesium. In the aluminium industry one sometimes will see fire sprinkler systems located above furnaces and in areas where dust accumulates. We recommend that every facility have a regular scheduled inspection for fire hazards. After identification the proper methods for extinguish those fuel sources if they ignite should be discussed and implemented.

Even though this incident involves magnesium. The use of magnesium in our industry for alloying is commonplace. The safe handling, storage, use of magnesium is very important. In terms of extinguishing a combustible metal fire here is a good reference article.

The Aluminium Times magazine had an article about this topic of combustible metal fires. That article can be found here.

Please comment.