Pitch Fibre Pipes
Pitch fibre pipes were mostly used from the 1950s to the early 1970s. Pitch fibre is made of wood cellulose fibre impregnated with coal tar pitch, under vacuum and pressure. These pipes are susceptible to delamination of their inner surface. They are also prone to collapse under applied pressure such as driveways. Even with no adverse ground conditions pitch fibre pipes can be expected to have a limited life span of around 40 years.
Fixing the Problem
A no dig technique to reform and reline problem pitch fibre pipes can be used. This entails winching a piece of pre-fabricated metal (which is the exact size of the original pipe) through the blistered and deformed pipe which reforms the pitch fibre pipe back to its original shape. High pressure water jetting is then carried out to ensure pipe walls are clean. A polyester liner which is impregnated with special resin is then inserted into the reformed pipe and inflated.