Wet-Out & Calibration

Best Practices – 8th in the series

This section will cover the choice of resin, measuring, mixing and “wet-out” of the calibration tube. We have three resin choices, Polyester, Vinyl Ester and Epoxy resin. While all three resins are acceptable for use according to ASTM F-1216 or ASTM F-1743, local agency codes may dictate which of the resins they approve for use. The majority of the agencies subscribe to the Uniform Plumbing Code or the International Plumbing Code and those two agencies have approved most epoxy resin systems for use on their side of the sewer lines. It contains no VOC’s and doesn’t hold the odor found in the ester family of resins. With that background follow these best practices for successful installations.

  1. The first exercise an installer must perform is to calculate the total amount of resin needed for the job. Each tube supplier will advise you the number of pounds per foot of tube needed to “wet out” the liner
    • Refer to the tube thickness and the recommended amount of resin to mix for that diameter and tube thickness.
    • Multiply the resin weight per foot of material times the number of feet of CIPP liner you intend to use for installation. (Example: if the resin needed for 3mm by 4” tube requires 0.8#’s per foot and you have 50’ of the liner to “wet out”, you would multiply 0.8 * 50’ and calculate 40#’s of resin.)
    • If your resin is a 4:1 mix, you would have a total of 5 parts. Dividing the total amount of resin needed by 5 parts will give you the amount of the 1 part. In this case, it’s hardener for the epoxy. Multiplying that number by the other 4 parts will give you the 4 part base. (Example: If 40#’s of resin needed to be divided by 5 equals 8#’s. This is the amount of resin hardener. Multiplying that by 4 gives us 32#’s of base)
    • A good practice here is to write those two values on the inside of the bucket where you intend to mix the resin. (8/32)
  2. Pinch the tube to be wetted out effectively closing the area of the tube that will line the pipe and start the vacuum pump by attaching the suction cup to the hole cut into the vacuum end of the liner.
    • Attach a funnel to the insertion end of the resin by taping it to the tube
    • Test the vacuum by pinching the tube to see that it is holding a vacuum.
  3. You should have set up a mixing area that protects the area from any spill of resin. In this area, you should have the resin base, resin hardener, scale, mixing bit in a drill and a timing device.
    • Set your mixing pail on the scale with the hardener and base numbers in your view for mixing.
    • Zero out the scale with the bucket on the scale so you weigh only the resin.
    • Pour the base resin into the pail. If the amount of resin is larger than a single pail will hold, divide the totals by the number of pails you plan to mix. (Example: for this exercise to prepare the same 40#’s of resin we’d prepare two pails with 4/16 written in each pail signifying 4#’s of hardener and 16#’s of the base in each pail.)
    • STOP. Review the work area as the timing has not started. Be sure that you have all the tools, supplies, materials, rubber bands, and cleaning materials before the next step. Once you have verified you are ready, prepare to add the hardener.
    • Set the scale of base resin in the pail to zero again. Pour in the amount of hardener (8#’s) into the base.
    • Apply the mixing bit and mix the resin.
      • Follow the recommended time. In our case, we recommend 3 minutes of mixing to completely mix the base and hardener.
      • Be sure to fully stir the resin from the bottom of the pail all around the perimeter and up to the top. Back and forth. If the resin is extremely cold you may need to add additional time. Failure to fully mix the resin here will give you poor curing results. In those areas where the resin is mixed too rich with too much hardener and not enough base may cure too quickly while those areas where it is little or no hardener, you may observe the resin never curing.
  4. Once mixed, pour the mixed resin into the tube holding the slug of resin in position to form a vacuum break.
    • Once the slug is added, remove the tube from the pinch calibration roller.
    • Move the tube with the resin slug to the calibration roller and run the inversion of the tube through the calibration roller.
    • Set the calibration roller to the recommended pinch setting (7mm for 3mm x 4” material)
    • Maintain the slug position above the pinch roller and let the vacuum pump pull the material toward the vacuum while you slowly process the tube through the pinch roller.
    • Do not pressure the tube to the point you over pinch the tube and make it weep resin through tears you’ve made by over pinching.

Next “best practice” is inverting the tube into the line. For more information call Pipe Lining Supply at +1-888-354-6464 or write to info@pipeliningsupply.com

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