Don't be too embarassed guys, it's not only the EE's - even us poor chemists slip up now and again....
Mine, I spent most of my working life with air & moisture sensitive materials, so was used to vacuum systems, Nitrogen or Argon padding, dried reactants, etc., until one day I was in charge of a new Acrylate modified Polyurethane product, and specifically the production scale-up after R&D.
Anyway, I wrote all the relevant production protocols, and sent one of the guys over to Germany for the first developmental production run, thinking no more of it. A day or so later when the first run started, I suddenly had an urgent call from Germany.... "the torque on the reactor agitator's going up... and the circulation pump keeps tripping out... what do we do ?" - Errr... shut it all down, full cooling, etc. etc... and cross your fingers ?! Net result, within minutes, one reactor of solid gelled polymer. Fortunately, it was a development scale reactor, so there was only about 6MT in a 10MT vessel at that point.
My mistake - being so used to air sensitive materials, I'd simply forgotten to add an air (Oxygen) feed & purge of the reactor, to stabilise the acrylate. Without it, the reactor contents had gone into free-radical polymerisation, and effectively set solid. In the end, it took 3 contractors several days, working with water-jet cutters & breathing gear inside the reactor, to cut the polymer out.
What do they say ? **** happens