Be present in the rehabilitation of the underground without disrupting the surface activity.
Epoxy & Polyurethane Linings
Epoxy and polyurethane (PU) liners are used in small diameter metallic pipelines to provide corrosion protection and semi-structural rehabilitation; Alterantively they are used in man-entry pipes, tunnels and manholes for leak protection. As with cement mortar liners, epoxy and polyurethane coatings require the host pipe to be thoroughly cleaned of hard deposits, nodules, scale, corrosion and other debris and be substantially dry prior to application of the coating to ensure good adhesion between the liner and the pipe wall.
Epoxy and polyurethane spray-on liners, like cement mortar, protect the host pipe from corrosion and improve the flow characteristics. A thicker coating of polyurethane can be applied to the pipe to provide semi-structural integrity and leak protection. Epoxy and polyurethane coatings inhibit corrosion by forming an impermeable barrier between the host pipe and the flow.
In small diameter (non man-entry) pressure pipes, a thin layer (1-1.5mm) of epoxy or polyurethane is sprayed on the wall using a high-speed, rotating nozzle. In most cases, the resin and hardener are fed through separate hoses and batched in a static mixer just behind the spray nozzle. The thickness of the coating is controlled by the flow rate and forward speed of the spray machine. Unlike cement mortar lining, the resin is not smoothed or trowelled after spraying.
Epoxy spray liners cure in approximately 16 hours, much quicker than cement mortar, while polyurethane spray liners cure in about 2 hours. Both liners are thinner than cement mortar liners. However, these liners are more expensive and require careful quality controls during application and curing to ensure that the lining is free of defects that may trigger corrosion.
Epoxy and polyurethane-based coatings are also used for rehabilitation and corrosion protection of larger man-entry tunnels, pipes, manholes and other water and wastewater facilities. The coating is applied by hand or sprayed-on. Thicker polymer coatings offer some degree of structural benefit and leak protection too.