July 13, 1995
The Bismarck Area Office recently investigated an oil drilling rig accident caused by inadequate guarding of the drawworks drum. During an oil drilling operation, the driller was in the process of raising the traveling block and the attached kelly and swivel assembly. An air-chugger winch cable was attached to the kelly pipe as a tag line to prevent it from swinging. Two of the rig hands were monitoring the kelly pipe as it was pulled out of the rat hole. The chain hand picked up the spinning chain and positioned himself near the drawworks drum as he waited for the kelly to be positioned over the hole. When he tossed the end of the spinning chain over his shoulder it became entangled in the fast line cable as the cable was spooled onto the drum. The spinning chain wrapped around the worker's wrist and pulled him into the drum as the chain's slack was drawn up. The spinning chain also struck the worker in the groin area and fractured his leg and severed his femoral artery. The driller stopped the drawworks before the worker was completely pulled into the drum encasement, but the worker was seriously injured. His leg was amputated and injuries to his hand resulted in a permanent disability.
The drawworks drum was equipped with metal casing that enclosed the drum on the lower front, top, and sides. However, there was an opening of approximately 4'x 3' to allow the fast line adequate clearances to spool back and forth onto the drum that has no barrier guard. (See figure 1)
Apparently, the drawworks drums used on oil well drilling sites were designed and constructed as described above without any barrier guard to protect workers in close proximity to the drawworks drum from the hazard of the ingoing nip point between the moving fast line and the drum. This design also exposes the workers to the potential hazard of contacting the moving fast line cable in the zone immediately above the drum casing.
To protect workers, a barrier guard or screens must be installed in front of the drawworks drum or mounted on top of the existing drum casing to effectively isolate the ingoing nip point hazard2. (See figure 2) The barrier or screen must be designed to eliminate any penetration by the worker's body parts such as hands and fingers, as well as materials such as chains or slings or any other object that could become entangled. The shield should extend at least 7 feet above the working level and effectively isolate all exposed sides. The guard should have features to allow for easy removal to provide access during servicing or inspection operations. The guard must be in place at all other times.
In addition to installing the barrier guard, all employers should inform workers of the potential hazard described and implement work practices to avoid the hazard of contacting moving parts such as hoist cables and rotating drums.
Please distribute this bulletin to all Area Offices, State Plan States, Consultation Projects and appropriate local labor and industry associations.
1 The Directorate of Technical Support issues Hazard Information Bulletins (HIB) in accordance with OSHA Instruction CPL 2.65 to provide relevant information regarding unrecognized or misunderstood health hazards, inadequacies of materials, devices, techniques, and safety engineering controls. HIBs are initiated based on information provided by the field staff, studies, and concerns expressed by safety and health professionals, employers, and the public. Information is compiled based on a thorough evaluation of available facts, and in coordination with the appropriate parties.
2 OSHA's machine guarding standard, 29 CFR 1910.212(a)(1) requires employers to ensure that "one or more methods of machine guarding shall be provided to protect the operator and other employees in the machine area from hazards such as those created by point of operation, ingoing nip points, rotating parts, flying chips and sparks."
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