Dropped Angle Iron from Drill Floor Ducting Support

A piece of angle iron weighing 7.75 kg, used to secure the draw-works exhaust ducting dropped from approximately 12m. The angle iron hit and smashed the re-enforced glass roof of the dog house, bounced 2m laterally (contacting one of the wireline team on their hard hat) and eventually landed a further 2m away on the drill floor.

Immediate Cause:

• the angle iron fell from the draw-works motor discharge duct after primary fixing bolts had either failed or worked loose.

Underlying Causes:

• Potential bi-metallic corrosion. Carbon steel bolts were used to secure the stainless steel angle iron section.

• The failed / loose bolts were not identified during inspection. The ducting inspection work order only called for a general visual inspection from drill floor level.

• Reliable securing practices were not utilised as evidenced by double nuts used on other parts of the structure.

• The draw-works exhaust duct is not captured in the weekly derrick inspection as it is owned by the platform maintenance & operations team