What it involves

Cured in place pipe (CIPP) lining, is the rehabilitation or reinforcement of pipes without excavation. It has become the method of choice for rehabilitation of deteriorated underground sewers and pipes due to its low installation cost, ease and speed of installation and minimisation of ancillary requirements such as traffic re-routing and security. Cured in Place Pipe (CIPP) Lining is a method of repairing a pipe using a flexible tube impregnated with a resin, which forms a new pipe within the original host pipe once the resin cures.

Heat cured, or ambient temperature curing CIPP lining differs from UV CIPP lining in numerous ways. The basis of all CIPP lining techniques is the resin matrix. The host material of the pipe is impregnated with this resin. Until curing, in this case by heat (hot water or steam) or by a time delay mixing catalyst, it remains liquid.

Unlike UV CIPP liners, heat and ambient cured CIPP liners can be manufactured or impregnated with resin on site and have a short shelf-life.

Preparing the product

  • A polyester fibre sheet is prepared. It is then cut and then formed into a tube that is the correct size for the host pipe. This material referred to as carrier material, liner, tube, sock. It’s typically purchased ready formed.
  • Lining sleeves have a thin coating on the outside, usually polyethylene (PE) or polyvinyl chloride (PVC-U).
  • Resins mixes, typically made of two or more components, and impregnated into and onto the woven liner.

The Process

  • Attach resin impregnated liner to one end of the host pipe and invert via water or air pressure through the host pipe. The inverted liner has the coating on the inside and the resin impregnated lining in contact with the host pipe.
  • Ambient cure resins require no input of heat or light to trigger the cure process. Once all the components of the resin mix have been combined the cure process will start and there will be a limited ‘pot-life’ to complete the installation.
  • For a hot water cure, the liner sleeve is installed by water inversion and once installed, the water in the hose is heated to 60-80ºC and circulated throughout the cure period (typically 6 – 8 hours).
  • For a steam cure the liner is inverted by compressed air and steam is then circulated to cure the lining.

Requirements

  • 4-6 hours site access (ambient cure)
  • 6-8 hours site access (steam cure)
  • 8-10 hours site access (hot water cure)
  • Over-pumping / tankering for high flows
  • 100mm – 300mm diameter (ambient)
  • 100mm – 1200mm diameter (hot water/steam)
  • For hot water cure: Tanker/Bowser for hot water supply and removal of resin contaminated water

When to use Ambient / Heat Cured CIPP and its benefits

  • Ambient and heat cured CIPP solutions are generally chosen in straight forward, low load situations.
  • Ambient cured liners have a very small site footprint and are consequently well suited to access difficult, smaller diameter pipes. Some variants such as Brawoliner use an epoxy resin mix and the host felt is expansive, allowing bends and diameter changes to be accommodated. The relatively fast cure times allow multiple installations in a working day.
  • Hot Water and Steam cured systems are generally factory impregnated and delivered to site in refrigerated lorries. The site footprint can be relatively large and cure times are longer.

How do we help?

Our staff including senior management have direct experience of installing ambient and heat cured liners for decades and have all received manufacturer training (Epros and Brawoliner in particular). We enjoy close working relationships with our liner and plant suppliers equating to an unrivalled technical support for our customers.

The long and strong relationships we have forged with manufacturers, coupled with high volume consumption, enables us to provide and install high quality liners at competitive prices

These systems are effectively installed blind, as they do not allow the pre-cure inspection afforded by UV cured for example. This makes it critical that protocols are closely followed and site-specific issues. These include sudden temperature changes, unusual ground water levels among others. These are observed with appropriate action taken. When things do go wrong, experience is vital to enable a practical, insightful and cost-effective solution. In these instances, the McAllister Group has the experience to correct these situations and deliver for customers.