In the post previous to this, I wrote that when the fires were lit in a naval boiler, only the two sailors actually lighting off the boiler are permitted in the firing alley.
There is a reason for that. Under the right circumstances, when the burner ignites, a rush of flame can come out of the light-off port (known as a "flareback"). It was a rare occurrence, but it did happen from time to time.
One day, back about 30 or so years ago, a young officer from the engineering staff of a destroyer squadron was observing a light-off on one of the ships in port. In order to get a really good look at the procedure, he stood right behind the Burnerman. The staffie was wearing the uniform of the day, Summer Khaki, which were made of gabardine, or what the Navy called "certified navy twill."
Those are fancy terms for "polyester."
A flareback occurred and the young officer was bathed in flame. If he had been wearing the standard shipboard working uniform for officers, known as "wash khakis", he'd have gotten away with some nasty burns, no doubt. But he wasn't and, as a result, the uniform pretty much melted onto his skin, or, as it was more crudely put, he was shrink-wrapped. He lived less than two weeks.
As a result, only cotton or fire-retardant uniforms were permitted in engineering spaces. And nobody, other than the two sailors performing the light-off, were permitted in the firing alley when lighting fires in a boiler.
Safety rules are written in blood.