Sealant lining large and branching small pipes - with excess sealant from small pipe returned to large and spread as top layer

摘要

The pipes are lined with sealant in succession by introducing liquid sealant and passing an appropriately sized pig through the pipe. Sealant forced into the small pipe when lining the large is returned into the large pipe using fluid or a pig and is then used by applying as a top layer to the existing lining by using a second pig of slightly smaller diameter than the first used for the large pipe. The second pig may be deformable to the required dia. by adjusting the back pressure used for running. A pig may consist of one or a pair of spherical foam rubber members and partic. for pipes with considerable bends, a pair of pigs is used with each consisting of two members interconnected by a flexible linear connector.