Alert 13 – 30 Failure to Torque Lift Sub Results in Dropped Monel Drill Collar
During tripping operations, the crew was in the process of making up the bottom hole assembly. The monel drill collar was brought up to the rig floor by the pipe-cat. A lifting sub was placed into the box end of the monel drill collar and screwed together with chain tongs. The drill collar was then picked up with the top drive elevators and pushed out of the way so a stabilizer could be picked up and placed in the mouse hole. The monel drill collar was then placed into the stabilizer, made up and torqued with the iron roughneck. The bottom hole assembly (BHA) was picked up out of the mouse hole with the top drive and pushed out of the way so a float sub could be brought to the rig floor. The float sub was then stood up and placed in the jaws of the iron roughneck and the monel/stabilizer assembly was stabbed into it. Chain tongs were used to make up these two sections while the iron roughneck was used as back up on the float sub. The iron roughneck was then used to make up the float sub to the stabilizer. At some point while the crew was making up the float sub to the stabilizer, the lift sub unscrewed from the monel. When the iron roughneck was removed, the BHA, which was sitting on the rig floor, fell out of the V-door and land on the pipe-cat.