Safety Incident Topic: Screen From Shroud On Roof Ventilation Fan Falls
Location Of Incident: Canada
Date Of Incident: 21th June 2003
Brief Account Of Incident
While using the overhead crane to move a barrel of lube oil, the screen from a fan shroud on one of the roof ventilation fans became dislodged possibly by the passing crane and fell approximately 40 ft. to the compressor deck below. The screen, measuring approx. 5 ft in diameter and weighing 40 lbs (see Photo #1 below) missed the person operating the crane by a distance of 15 to 20 ft. Fortunately; he was the only person in the Compressor Building at the time.
What Went Wrong
A self-taping screw and tab holding the screen in place failed (possibly due to fatigue caused by vibration) allowing the screen to hang lower, and into the path of the overhead crane where it was caught and pulled loose.
What Went Well
- No injuries or property damage occurred as a result of this incident
- The fan was immediately locked out and tagged to prevent further use until inspected.
- An investigation was conducted and follow-up action promptly implemented.
System Root Causes
Inadequate technical design: The screens are held in place by only 4 small tabs welded to the screen material and secured to the fan shroud with self-taping screws. This design for securing the screens is evidently prone to failure, as other broken tabs and screws were also found on other fan screens.
- A Management of Change was initiated and the remaining screens have been temporarily removed.
- The manufacturer of the fan assembly has been made aware of problem and asked to design a better means of securing the fan screens to the shrouds. All screens will then be reinstalled