During recent reeving drilling line operation using the Lewis Snake Grip the snake grip slipped (when the snake was 75 ft away fr the drum) causing the 1 5/8"
drilling line pulled backwards over the Fast line sheave and falling (from approx 160 ft) on the drill floor shattering the drillers doghouse window. Despite following the OEM procedure and with the tension on the snake grip 1/4 of the rating it still slipped. Checking IADC data for similar incidents (there were 2 reported) most of them were due to not following the recommended procedure.
Question to the community: what type of grip do your respective rig contractor use when reeving drilling line on the rig.
The Lewis snake grip is a safe method of changing both drill line and tugger wire as they can be run through sheave's with care. Most other solutions tend to hang up. It is important to follow the manufacturers guidance. The critical points being to clean the wire of all lubricant and have a clean cut at the wire ends. Seize the end of the bare wire or even weld it if possible. Use the smallest snake you can slip over the wire. It is better to struggle on a smaller snake than risk a loose fit with the next size up. Use a metal binding clamp at least around the base of the snake grip (open end). I recall the manufacturer's literature recommending a few clamps but I always figured this may prevent the grip from getting a proper grip.......Regardless, have the contractor use a few lengths of old wire as a trial (chain pull between the base of some Samson posts) and see how they get on. Preparation and care is everything on this job.