BSEE informs of an incident where an auxiliary line’s abrading caused a rope guard to fail, and provides lessons learned.
The incident
A BSEE investigation found that chronic scraping and rubbing by an auxiliary line created enough damage to the main line idler sheave carrier side plate, pin boos, rope guard, and auxiliary line that it caused the guard of the main load line idler sheave carrier to fail.
The rope guard fell approximately 100 feet, landing near personnel working below.
This damage occurs when the auxiliary line is used at high rates of speed, causing the auxiliary line to jump onto the main line idler sheave.
This incident involved an American Aero OM 450 crane; other cranes with a similar configuration could see the same issue.
Lessons learned
- Inspect idler sheaves and wire ropes for wear indicative of friction and abrading when performing pre-use inspections described in API RP 2D.
- Replace single main load line idler sheave carriers with a double sheave idler.
