Calibration Tube Failure

“Your calibration tube failed. It popped when I blew it into the liner. Thankfully I had more calibration tube and shot another one that held but I am nervous about using it in the future. Can’t you make it stronger or out of a different material that won’t pop when inverting it?”

Let’s figure out what caused the problem before we redesign a proven method of inflating liners that’s been used for well over 20 years. From looking at what caused past failures we can eliminate those from the cause of this failure unless they happen to apply to your issue. There are 3 failures that we’ve identified in the past.

  • The first failure is the knot used at the end of the calibration tube. We’ve seen knots fail from clamps used coming loose or breaking and coming off the end of the tube during curing. This problem has been resolved by using our proven clamping method that you can find on the video section of the
  • The second failure comes about from sharp objects left in the host pipe after cleaning. These can be needles, shards of broken clay tile, or other objects with sharp edges. After cleaning pay particular attention to the areas where the calibration tube is exposed before entering the liner tube and after exiting the tube close to the stopping point of the liner tube. As the calibration tube passes by these sharp edges, tears and rips can occur not letting the calibration tube hold air, steam, or water. If you overlook this step be prepared to have a calibration tube fail.
  • The last failure is exceeding the pressure rating of the calibration tube. This is easy to do by letting the pressure build to invert the calibration tube quickly. The calibration tube hits the end of inverting at such a speed that the inversion pressure sees an instantaneous transient load that pops the liner. This usually occurs at the seam somewhere in the last half of the calibration tube. We see this failure more often when using hoses to invert liner.

In addressing your final question regarding installing a more durable calibration tube, you can. Using the blue discharge hose material used to drain pools and ponds can be used but you will be spending extra money to mitigate a problem you could easily solve on your own.

For more information call us at 888-354-6464 or 714-630-6311. You can also contact us at

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