#12: Pull-in-place liners… the hot water cure

Recently, one of our customers mentioned he’d had a problem with his pull-in-place liner which had failed to cure when he pulled the bladder. He was surprised when asked, if he had used hot water to cure his resin.


There were several junctions on the drain being lined, which they intended to sort out after the liner had cured. The junctions were still live and some of the branch drains were used while the liner was curing. The cold water in the branch drain built up head pressure behind the liner. The cold water delayed the cure of the resin at the junctions. When the bladder was pulled the water pushed against the back of the liner causing it to collapse.

When we explained to the contractor he could have used hot water to cure his resin he was surprised. He believed hot water and steam were only suitable for inversion. In fact, hot water curing a pull-in-place liner is actually easier than it is for inversion. The simple explanation is that hot water from our diesel boiler goes in one end and flows out the other end.


Here’s a quick how to guide, with the really important bits highlighted so you don’t miss them:

  1. Build your bladder with our larger cotton reels on both ends – they have a 3/8″ male thread with a hose barb that accepts a garden hose.
  2. In addition to installing a pulling strap into the drain, install a hose that will act as the discharge hose.
  3. Pull your liner into position and, before you fill the bladder with cold water, you must check the discharge hose with your camera to ensure that there are no kinks. A kink in the discharge hose will mean that the water can’t escape and you risk over inflating the bladder.
  4. Attach the Pipe Core pressure relief manifold to the downstream hose at ground level. The manifold is fitted with a temperature gauge, a pressure gauge, a pressure regulator and an emergency discharge ball valve.
  5. Attach your Pipe Core Power Box Diesel Boiler to a garden tap on the inlet and the outlet from the boiler feeds into the bladder.
  6. Run hot water from the boiler, through the bladder and adjust the regulator to discharge at the desired pressure. The discharge can go to a waste pipe, or onto the garden.
  7. Follow the curing chart on our website, depending on the resin that you choose.
  8. After curing time has been reached, it is important to slowly cool the resin back to ambient temperature. We recommend reducing the thermostat on the boiler in 10 degree increments every 10 minutes until you have dropped the temperature back to 20 degrees.


If you need some advice on hot water curing or would like a quote for a boilerand downstream valve give us a call, drop us a line or drop in to see us at our factory in South Melbourne.