Bolted Connection Failure of Explosion Proof Enclosure & Subsequent Personnel Injury




Introduction: In 2014, a contract employee was working on an oil rig during drilling operations. This particular drilling rig and operations utilized a closed loop system for the drilling mud. The mud is injected into the well bore, exits the bore with drilling tailings, enters a shaker to remove large debris, circulates through a centrifuge to separate the remaining drilling debris, discharges into a holding tank, and then recirculates back into the well bore. The drilling rig was equipped with two centrifuges for 100% redundancy. During operation, one of the centrifuges would trip on an automatic safety shutdown. The service company that owned and leased the centrifuge was contacted, and a technician would be dispatched to examine the centrifuge, address any automatic trips, and re-start the centrifuge. At one point, the contract employee working on the oil rig attempted to re-start one of the centrifuges by pressing a button on one of two enclosures for the centrifuge through use a wooden handle. An event ensued, dislodging the cover of the enclosure and resulting in the employee falling backwards a nd injuring himself.

Authors: Henry V. Mowry

Keywords: Bolted Connection Failure, Explosion Proof Enclosure, Explosion, Threaded Connection, Torque Specification, Torque, Bolt Torque

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Page Count

7 pages


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