Once upon a time...
I once spent 6 weeks as a junior project manager assisting in the commissioning of a new aluminium smelter in Australia. An aluminium smelter is a 1km long line of reduction pots, driving 300 thousand ampere of electricity through some nasty concoction of aluminium oxide and fluorine compounds.
Each pot consists of a carbon anode bath and a carbon cathode that dips into the molten bath. However to start the system up you need to pour molten aluminium into the dry bath. The thing doesn't do a cold start. I had the privilege of watching one of these pot "chargings". Now there is something to know about molten aluminium. It doesn't like water. In fact water and molten aluminium is an explosive mixture and great lengths are gone to to keep water out of the potline. No drink bottles or any other fluids are allowed on the line. Drop a drink bottle in a pot and it would be like dropping in a kilo of TNT.
The way to proceed with a charging was to take a car sized crucible of molten aluminium and pour it down a ceramic sluice into the pot. Now on this day I was standing on the edge of the potline watching the crucible being carried over to the dry pot on a crane. Next to me was an old guy, a boiler maker by trade whose main job was as a welder. He was probably not university educated and he had a rough country accent. He'd spent a long time on the pot line and had seen it all.
He took me aside and told me to stand well back from the ceremony. He added that he'd also told the professional engineers and managers standing around and already congratulating themselves that they were a big mistake. The ceramic sluice had been left out in the night air. The boiler maker knew that this meant the sluice was damp. Damp and aluminium was a very bad thing. The engineers and managers thanked him for his information and told him to bugger off and stop interfering with their tight schedule. So there we stood, him and I, waiting for the inevitable.
As the molten alumnium was poured into the sluice it exploded and pretty little balls of very very white hot aluminium went flying into the air. Nobody was killed or injured but only by luck.
Now my boiler maker did his job and passed on information about the dangers he saw. He did his duty. If one of those engineers had got himself killed who would fault the boiler maker.