Chain Knockers and Sand Paper

“How often should I be replacing my chain knockers and sandpaper for my sanding device?”

Unfortunately, chain knockers and sandpaper replacements are consumables that wear out. How fast they wear out depends on a lot of 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 axel will chew up the knockers faster than cleaning roots in a clay pipe. The centering axel keeps the chain knockers centered so that the chains remain somewhat centered and away from flopping 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 the extent that unrestrained chains bang against the pipe wall. An added benefit for the use of centering axels 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 cloth to help extend the life of the sanding operation 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 here is to clean the pipe with a jetter that uses hot water as opposed to cold water applications. This breaks up the grease before you introduce the sand cloth to finish removing the scale. Again, a centering axel can help you keep the sander centered and not slamming into the pipe wall.

If you use your devices are 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 add in replacement costs for every job for the consumables you are using. Whether it’s 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 your factors of costs. If you are replacing chain knockers every couple of hundred feet, add that cost to your per-foot costs for the job and price it accordingly.

For more information contact us at 888-354-6464. You can also email us at

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