Two operators were sent to change valve positions and bring a pump on line. When the valve would not open, the operators decided to remove the gearbox to access the valve stem directly and open the valve with a wrench. This activity could be done without affecting the valve top cap on most valves of this type. However, this valve was a different model. When the operators removed the gearbox from this valve, the operators also removed the mounting bolts that secured the valve top cap.
When the valve was opened manually, a large vapor leak occurred, ignited, and caused serious damage.
Situational Awareness: Check Before You Act