Bursting Disk Fitted wrong way up
A pilot plant vessel was being evacuated and purged with nitrogen in readiness for charging with a flammable solvent. The chemist found it was impossible to hold a vacuum. He later found that pieces of the bursting disk had fallen into the vessel, the disk had been mounted upside down, and therefore below the vacuum support, Fortunately the disk failed, had the vessel been used without a vacuum test, it would have have not safeguarded the vessel and it's glass overheads in the event of a pressure rise - instead of bursting at 2-3 psig, it would have been well in excess of 15 psig before it would have vented.
The type of bursting disk used is well labeled and fitters are aware of the dangers of incorrect fitting. No one accepted responsibility.