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Steam Cure Liner Installation Process has become common place for installing 6″ to 15″ diameter CIPP liners. Steam is used in conjunction with pressurized air that inflates the liner against the host pipe and distributes the steam from one end of the liner to other. When using a steam cure, the liner can be positioned within the hose pipe by the water inversion method or with the use of an air inverter (shooter). If the winch in place method is used, a double coated liner is required.
Most CIPP liners use thermosetting or heat activated resins. Heat, through water or steam must be transferred evenly throughout the liner to properly cure the resin. Heat transfer must be monitored to prevent over heating the resin (called resin boil) which can weaken the finished liner.
Use of steam cure is normally faster than hot water cure, as steam heat transfer is quicker. Steam cans are attached at both ends of the liner with pressurized steam-air mixture introduced at one end and allowed to discharge at the other end. Once the cure has completed, pressurized air is allowed to flow through the liner to cool the liner. Set up of a steam cure system is quicker than a hot water cure system.
Mobile high volume steam generators or steam boilers are used to produce steam that is introduced into the pressurized air stream. The pressurized stream-air mixture is connected to one end of the CIPP liner through a steam can. At the opposite end of the CIPP liner, a steam control station (“B” Station), and a steam discharge muffler is attached. The “B” Station is used to regulate the internal air pressure within the CIPP liner and the flow of the steam-air mixture through the CIPP liner. The steam discharge muffler is used to suppress noise and safely disperse steam to the environment. Upon completion of the resin cure or exotherm, the steam source is shut off but the pressurized air flow is maintained through the CIPP liner. Air flow is used to gradually cool the liner as per the resin to prevent shrinkage.
The advantages of using steam curing are the installation and cure time are a lot quicker than traditional methods, the site footprint is largely reduced and we have the option to get equipment in and out of difficult locations with ease.