What Does Chinese Finger Mean?
A Chinese finger is a woven wire mesh-type device that is used to pull a new cable or wire with the existing cable or wire that needs to be replaced. The Chinese finger can expand or contract to grip different or same sized cables or ropes and can be used to pull materials into a bore. It is placed over the material and when pulled, it tightens on the material and becomes even tighter, and increases its grip the more it is pulled. It is also used for the transfer of tension from lifting devices to a flexible pipe.
The Chinese finger saves time lost in the stringing process as it does not require any special tools. The swivel and swing links pass smoothly through the blocks and prevent line twisting. The ends of the grips are always seized by banding and taping. The LSG and LSG-X snake grips manufactured by Lewis Manufacturing Co. essentially perform similar functions with the exception that the LSG-X cannot be taken apart in the middle. It is permanently attached via a swivel tube that makes it difficult to be used for pulling in tight spaces.
The swivel tube assembly has a heavy-duty friction swivel and is used where the separation of the two elements of the pulling grips are not required. The size range and the working load of the snake grip are clearly stenciled on the swivel tube assembly and care should be taken to use it within permissible limits to prevent accidents and injury.
A Chinese finger is also known as snake grips or socks.
Trenchlesspedia Explains Chinese Finger
The woven steel wire or fabric sleeve called the Chinese finger or snake grip is flexible and adjustable and makes stringing quick, easy, and safe. However, the improper use of these devices can cause serious accidents resulting in injury and even death. The manufacturer provides detailed instructions in the user manual which should be strictly followed to avoid mishaps.
As per a safety warning from Lewis Manufacturing Co. snake grips used in harsh environments such as offshore drilling platforms and saltwater conditions should not be used more than once. Snakes grips that are not used in corrosive environments can be reused if maintained properly and given careful visual examination before and after each use. If any defects are detected, the Chinese finger should be discarded immediately.
Snake Grip Banding Instructions
For using Lewis Snake Grips, it is mandatory to follow banding instructions. The complete instruction can be found in the user manual. The right size-range grips should be used for the line or rope being pulled. The grip should be inspected for abrasion or brakes and should be discarded at the first sign of damage. The area to be loaded into the grip should be clean and should be completely free of oil and grease by using a high-grade degreaser and heavy-duty disposable towels. The cable should be loaded all the way into the grip and when properly loaded the tail end of the grips should be banded and taped using a banding tool and electric tape.
The Bureau of Safety and Environmental Enforcement (BSEE) recommends the following when installing them on the drill line cable.
- Assure the manufacturer’s specifications and instructions for use of a snake grip are followed completely.
- Verify the correct sized snake grip is utilized for actual drill line diameter during operations.
- Drill line cables must be thoroughly degreased before insertion into snake grip.
- Use the proper manufacturer recommended clamps and tools to secure the snake grip to the cable.
- Maintain a safe operating speed on the drill line winch to ensure safety observers have adequate time to relay any and all safety concerns during operation.
- Be assertive in personnel placement while conducting this type of operation. When possible, keep personnel clear of drop zones of all the overhead equipment and work.