Two technicians working with a subcontractor died from anoxia in a refinery while carrying out maintenance work on a down reactor that was part of a hydrocracking unit.
One of the technicians descended (or perhaps fell?) into a reactor filled with a nitrogen atmosphere in order to recover a roll of adhesive tape left inside and lost consciousness. The second employee on the exterior platform climbed down into the reactor to rescue his colleague and became unconscious as well. A third technician on the scene sounded the alarm. The emergency response team arrived in approx. 10 minutes, each wearing a self-contained breathing apparatus, and evacuated the two victims who could not be resuscitated. The oxygen content inside the reactor, as measured by rescue personnel, was less than 1%.
The follow-up investigation pointed to inadequate warning signage (absence of any signs indicating “risk of asphyxiation due to a nitrogen atmosphere” or barriers blocking access to the opening leading inside the reactor), an erroneous work permit with no mention of the presence of nitrogen in the reactor and a lack of information and training provided to personnel on the inherent hazards associated with oxygen-deficient spaces.