Welding/Gluing Calibration Tube To Lining Materials

“We were at one of your training sessions and saw you weld a section of green calibration tube to the coating on your lining material and then invert it into the pipe. You used a flat iron to weld the two together, then inverted it to start liner after the turn of a combi. We attempted the same but must have missed something since our cal tube separated after the turn and we couldn’t get a calibration tube through the liner to cure it. We fished it out and tried again but the same thing happened. What did we miss?” Dave

Dave, I understand your pain. Let’s go through the basic steps and see if we can narrow down one of the reasons for the failure.

  1. Prepare the liner and the used or new calibration by making a square cut to ensure the same dimensions are even and not cut at an angle.
  2. Turn back the calibration tube approximately 1” to 2”.
  3. Using gloves, clean the turned back calibration tube surface and the 1st inch of the surface of the liner you are attaching the calibration tube to. The gloves will prevent contamination of the surfaces by oils found on your hands.
  4. Carefully turn the cuff on the calibration tube back to its normal position.
  5. Slip the calibration tube approximately 1” over the liner material. This preparation is done before wet out.
  6. Heat flat iron to 400F. Use an infrared thermometer to ensure the temperature you need.
  7. Use a heated flat iron to 400F and slide the iron over ½ of the assembly, clamping down on the flat iron and holding it for 12 to 15 seconds ensuring that you catch the lining material leading edge so the very edge of the liner is welded to the calibration tube.
  8. Upon completion of the last step move the flat iron to the other side and repeat.
  9. Let cool and inspect the weld. If you have edges not welded, you can use the flat iron to dress the edges.
  10. Feel the assembly to ensure that the leading edge of the lining material is firmly welded to the calibration tube by feeling the calibration tube to see that the edge is attached. Try tearing it by pulling it to ensure it’s secure.

Here are the 3 most common causes for the liner to separate prematurely during inverting it into the pipe.

  1. Failure to fully clean the surfaces to be welded and touching the surfaces without gloves before welding
  2. Welding the surfaces below 400F or not holding for a full 12 to 15 seconds
  3. Not welding the leading edge to the liner material to the calibration tube. This allows air to flow under the loose leading edge allowing it to be peeled off.

These steps and prevention of the 3 conditions that contribute to failure may help you in the future. One other consideration is that the green calibration tube is a PVC material and the coating on several of the lining materials we carry has a PU coating. While they will weld, the dissimilar materials won’t have as strong a bond as using the same coating and calibration material. When ordering you may want to order the coating to match the calibration tube if you intend to use this method regularly. We stock both materials.

For more information contact us at +1-888-354-6464 or email us info@pipeliningsupply.com.

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