Wow, that's a name I haven't heard in over twenty years. There were two companies that I remember that used to do that sort of work. Fermanite was one and it seems like Federal Industrial was the other. I agree with you that I can't see how anybody that does that for a living could ever pass Fitness for Duty or any other thing that requires sane people.
If I'm not totally off, these are the guys you hire to stop live steam leaks and such without shutting the unit down. I watched them seal a leaking main steam valve at Palisades back in the early 80's. The thing was roaring like a jet engine at full power and had steam cut one of the bonnet bolts completely and was working on cutting the two on either side. They went in and clamped a fixture around the bonnet and pumped it full of this stuff that was like a nuclear grade hardening Permatex. All the time they were saying that the added stress of actually pumping this stuff in might break the other bolts and cause the bonnet to come off completely.
I couldn't tell if they were highly skilled and confident, crazy, stupid, or drunk but I got the impression that it was a combination of all of these. Nuttiest thing I ever saw anybody do.