Thermoformed pipe lining is yet another method of trenchless pipe rehabilitation. They are used extensively in industrial, sewer, and storm pipe repair. They can even be used in repair of potable water pipelines because they are non-toxic. There are two types of thermoformed pipe liners namely, polyethylene made deformed and reformed pipe liners & polyvinylyl chloride (PVC) made fold and form pipe liners. These pipe liners are deformed, flattened or folded into C, U or H shape at the time of coiling.
Thermoformed pipe liners can be used in pipes of different diameters and their size ranges from 3″ to 30″. The host pipe is first cleaned of debris and other obstruction after which the coiled liner is pulled into the host pipe using a winch cable. During the thermoforming process, steam and air under pressure is used to expand the liner and stretch it to tightly fit the host pipe. While the liner is under pressure chilled air is passed through the pipe to maintain the fit. The liner confirms to the shape of the host pipe providing a sort of mechanical lock. The ends of the liners are sealed. This method is quick and because it is resistant to abrasion and corrosion, it lasts for many years.