Note: I’m not your typical tech support. I’m a Field Service Engineer for large foundry furnaces. This equipment melts metal and is used to pour it into molds to cool for our clients specific products, such as car parts, pipes, faucets, fire hydrants, etc.

This happened in October. We were installing a new system for a client who had a fire 8 months prior. As a result they had to lay off their experienced employees and hire new operators as the foundry came up and running.

Our job was all but complete. The furnace had been installed. The power supply was working. The PLC and HMI was programmed. We just had a few minor communication errors to fix up and had to train the operators.

On our remote panels by the furnace there are a few main buttons. There’s power on/off. Hydraulics on/off. Lift/tilt. Open/close cover. And of course an emergency stop.

During training the operators were instructed to never hit the emergency stop unless it was an emergency stop. This button is hard wired into the HV breakers to turn off the power. In order to turn it back on, maintenance would have to do it. No big deal right?

Unbeknownst to myself, or their managers, the guys in charge of buying this equipment decided to request that this emergency stop should stop not only HV, but all power. Period. This includes control power.

One of our first days of operation, a green operator was going about his business. He was pouring the molten metal out of the furnace into the ladle. Being new with it he tilted the furnace a little too far. And by too far I mean he pretty much brought it to it’s 90 degree angle.

He panicked. He hit the estop button. Instead of lowering the furnace, he killed the power.

That’s fine, he can still bring the furnace back down right? Nope. Hydraulics get turned on by control power. Management wanted estop to kill all power. This killed the hydraulics.

Except no one knew.

The furnace kept pouring. The 12 metric ton ladle began to over fill (they normally only take 9 tons at a time out).

He panicked more. Hit the estop again. Got his supervisor. The ladle began overflowing. The hydraulics won’t turn on. God, why won’t the hydraulics turn on?

They called maintenance. By this time the ladle is taking in metal on one side, and spitting it right back out the other. Molten metal flying everywhere. The iron was at pouring temperature. Roughly 2800 degrees F. Or 1490 C for you non-Americans.

Maintenance couldn’t turn the hydraulics on. Where’s the shut offvalve? What? There’s no manual one? Can we get power back? Get a 40 cal suit! Get this back on!

The metal keeps flowing. Then the worst happens. Arc flash. Everyone sees it. Their holding furnaces lose power.

You see... what did they put on the wall across those furnaces? Conduit. Idiots.

The molten iron melted away the conduit and the copper wires that was the feed to the holding furnaces.

Luckily, they were able to change the feed around for those furnaces so they didn’t have a slug in there.

But all in total. They emptied 36 metric tons of molten iron into a 12 ton ladle. It took days to clean up. I’m surprised the wall is still standing.

After that event, management decided to allow us not to kill the control voltage with an eStop. And introduce a manual release valve on the hydraulic pump.

I’m just happy no one died.