Two employees were bolting round flanges into a pipeline formation. One employee was torqueing with a ratchet while the other was holding a multiplier that was attached to the ratchet with the use of an extender. There was another 2" flange (which extended further out than the flange that was being bolted) that was in the middle of the flange that they were bolting. They were torqueing the bolts on the flange in sequence/series. When they started the last round of torqueing, the employee holding the multiplier got his pinky caught between the multiplier and the center flange. This resulted in a partial amputation of the left pinky finger. The employee had removed skin form the very tip of the finger and the nail bed.