Dropped Pipe Spinner Injures Floorman

There is something to be said for following proper work procedures, including the inspection of tools and equipment.

Here is a prime example:

What Happened?
A floorman was running the pipe spinner during a trip. As he finished backing out a joint of drill pipe, he pushed the pipe spinner back to its stand. At that point the top U-bolt on the piston backed out from the piston arm. The pipe spinner dropped approximately four feet to the rig floor. The force of it pushed the floorman to one side and he fell backwards, sustaining a twisted ankle and bruised knee.

Why it Happened?
An investigation determined that several items contributed to this incident:

The pipe spinners were not inspected prior to beginning the job.
The safety cable was not properly attached to the tongs. A cable was attached, but it would only give protection in the event that the shackle (connecting the tongs to the hanging line) failed, not if the piston arm came loose.
There was no swivel installed in the hanging line to allow the tongs free movement without affecting the hanging mechanism.
There were not enough threads on the eye that screws into the cylinder shaft to allow a jam nut to be installed.

Don’t Let it Happen to You
To address this incident, the company did the following:

Instructed the personnel on rigs that pipe spinners are to be included in their inspection program.
Rerouted the safety cable to protect against any part of the hanging mechanism failing.
After checking with the manufacturer for the information on the correct swivel to use, they installed a swivel in the tong hanging line to allow free movement of the tong without affecting the hanging mechanism.
An eyebolt with longer threads was installed to allow for a jam nut to be installed.
To prevent accidental backing out, a thread-locking compound was used on eyebolts installed into the hanging cylinder.
A safety meeting was held with all crews emphasizing the importance of checking all equipment for irregularities prior to use.