Solving Cured-in-Place Pipe Problems

Knowing the next steps can save the job when cured-in-place liners fail to cure properly.

Trenchless pipe lining is an effective way to rehabilitate underground pipes, but nothing is ever 100 percent perfect, in life or in plumbing. All property renovation projects are vulnerable to error, whether it’s roofing, electrical work or pipe lining.

If you line pipes, sooner or later you’ll have a liner that doesn’t cure properly or one that gets washed away during the application process; it’s a risk in any project. When this happens, what’s important is identifying the best next steps for solving the problem.

When a liner cures incorrectly, there’s no going back and starting over, but it’s not necessarily as bad as you might first think. It’s still possible to reline the pipe without invasive — and expensive — digging. Before this can be done, however, the first step in repairing a faulty or partially cured liner is pinpointing the cause.

The cause

Generally speaking, there are two main reasons a pipe liner doesn’t fully cure. Either:

  • Water flow within the pipe disrupted the curing process and washed away lining material mid-application; or
  • The compounds in the liner resin were incorrectly mixed, resulting in an incomplete final product

Video inspection should always come first in diagnosing the cause of the problem. The same processes and technology used initially to identify damage in a pipe are also valuable in pinpointing why a liner didn’t cure correctly. Video inspection is the most reliable method of identifying a pipe problem, whether it’s a partially cured liner or a full-blown pipe collapse.

With video inspection tools, we can diagnose the problem by checking the state of the resin (or the complete lack of resin, for that matter). If there’s little or no resin remaining, it’s likely that some source of water flow washed away the resin before curing.

On the other hand, if the liner looks overly saturated and the resin will not cure with conventional methods, the resin compounds are probably mixed incorrectly. Either way, the next steps depend on how much of the liner failed to cure successfully.

Partial failure

If the lining material did not successfully cure in only a specific segment of pipe (often when lining fails due to water interference), there’s no need to reline the entire length of the pipe. Instead, you can use a sectional point repair process to reline the affected segment, which is a much more affordable solution than relining the entire pipe.

When using sectional point repair for this purpose, an inflatable bladder is used to reline the affected segment. Since the repair is confined to the specific affected area, the overall process can be completed in a few hours. Sectional point repair is also ideal for dealing with root intrusions and other pipe damage limited to a specific segment of pipe.

The full fix

If an entire liner does not cure correctly, as is often the case when resin compounds are incorrectly mixed, the first step in resolving the problem is attempting to pull the faulty liner out of the pipe with a cable. If the faulty liner can be removed this way, relining is as simple as starting the process from scratch. If the bad liner can’t be removed, however, the best option may be to simply line over the existing liner. This can take longer but will ultimately solve the problem.

In the worst-case scenario, the pipe may have to be excavated using traditional dig-and-replace methods. This is unfortunate, but also 100 percent reliable. Due to the costs of each of these methods, trenchless point repair or relining should always be tried first, with excavation saved as a last-resort option.



Discussion

Comments on this site are submitted by users and are not endorsed by nor do they reflect the views or opinions of COLE Publishing, Inc. Comments are moderated before being posted.