Resin Run Up – Do You Know What It Is And How To Prevent It?

Resin Cutting Head

“I just got done lining a 4″ service lateral that had one 3” tie-in. When I went to reinstate the tie-in, I came from the backside to cut it out using your cutting tool. I got it out but it took over an hour of grinding to get it out of the pipe. The questions I have are: Does the cutting tool get dull? Did I operate the UHS unit incorrectly? How can I be sure I’m getting full power out of the UHS machine – could it be delivering fewer RPM’s than advertised?

Let’s start with the main issue here, reinstatements. Years ago I learned this lesson early in my CIPP mainline career. The issue is “resin run up” and it occurs when pressure from the curing process drives resin up service tie-ins. While using pre-liners in mainlines wasn’t possible for a number of reasons, our only option was to cure the liner at a lower pressure to minimize the amount of resin running up the tie-in. The higher the curing pressure, the more the resin runs up and cures in the tie-in. There is a tremendous amount of difference between curing at 5 psi as opposed to 10 psi. Trying to remove a 4″ cured slug of resin in a 6″ tie-in is a pain and time consuming. Some were bad enough that our mainline cutters couldn’t reach far enough up

Wire Brush Cutter

the tie-in to get it all out so we ended up digging a pit at the right of way and reaching it from the backside. We’d then install a clean-out at that point if one didn’t exist before this. And guess who paid for it? Yep, we did.

So here’s some options that will help with future jobs. Obviously, curing at a lower pressure will keep resin from migrating up the tie-in, but there may be other reasons to cure at a higher pressure such as ground water or turns, bends, diameter size changes, and offset joints. If these come into play, installing a pre-liner will prevent excess resin from migrating up the service tie-in. You can use an old calibration tube as a pre-liner for this purpose. Just invert it prior to shooting your liner. Regardless of the pressure you apply during the cure, the resin can’t run up the tie-in, making reinstatement much easier.

UHS Drain Cleaning

Your other questions are also good ones. Yes your cutter can get dull and lose either cutting surfaces or carbide cutting chunks placed on the tool to act as a cutting device. If using a cutting tool that has a sharpened blade(s), you can feel them with your fingers for sharpness. Filing or grinding can resharpen the cutting surface. If carbide cutting surface, send them back to us for re-surfacing. This is a much less expensive process than throwing them away and buying new ones.

Operating the UHS tool requires some patience and finesse. Jamming in the tool into the slug is like over pressing a drill bit through hardened steel. A little pressure and time gets you through but too much pressure heats and dulls your drill bit very quickly. Adding a little pressure and letting the bit do the work is the best advice here.

Finally, your drill motors are typically operational or dead. In thinking back to all of the drills I’ve used over the years I can’t think of one that got slower and slower as it aged except for battery powered drills. It usually goes from full capacity to dead unless it’s battery driven in which case it does slow down. For cleaning, battery operated drills are not the best choice.

Hopefully these thoughts will help you in the future with this issue. Planning ahead should help you from spending extra time performing tasks that don’t make you any money but still need to be done.

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