Unfortunately, chain knockers and sandpaper for sanding devices are consumables that wear out. How fast they wear out depends on many factors including the type of pipe you’re cleaning, how aggressive you are operating the cable, and the materials you are finding in the pipe you are cleaning.

Scale in cast iron pipe using a chain knocker without a centering axle will chew up the knockers faster than cleaning roots in a clay pipe. The centering axle keeps the chain knockers centered so that they don’t flop against the pipe wall. While you get some contact with the actual pipe, centering the chains keeps them from banging against the pipe wall to an excessive extent. An added benefit for the use of centering axles is to protect the pipe wall from the force of unrestrained chain knockers.

Sanding devices chew up sand cloth even faster. We use cloth material for the sand component to help extend its life as paper in a damp environment doesn’t last at all. Even with our best efforts to produce these materials, adding grease to scale can foul the sand cloth pretty fast. A good practice is to clean the pipe with a jetter that uses hot water as opposed to a cold-water application. This breaks up the grease before you introduce the sand cloth to finish removing the scale. Again, a centering axle can help you keep the sander centered and not slamming into the pipe wall.

If you use your devices primarily for cleaning out roots, you are most likely finding that both the sander and the chain knockers last a lot longer than cleaning scale. The most important issue for you is to make sure you account for replacement costs in every job for the consumables you are using. Whether lining or coating, you always figure out the cost of the liner and resin you need for the job. With consumables, you should determine a factor of costs for your cleaning operation as well and these two items should be part of those cost factors. If you are replacing chain knockers every couple hundred feet, add that to your per-foot costs for the job and price it accordingly.

About the Author

John Heisler is the owner of Pipe Lining Supply and Quik-Lining Systems. He has more than 20 years of experience in the CIPP lining industry and 40-plus years in the underground construction industry.