Repairing pipework in-situ

Alumnus David Krampf was involved in a project to develop a system to apply a structural internal coating to non-man entry sewer pipes in the 1980s.

At the point at which a pipe was cracked, this innovation would seek to repair the pipe in-situ, without needing to dig up the pipes. Pipes may be cracked or damaged by heavy vehicles above, or via roof ingress through joints or cracks.

Using two manholes, there would be minimal disruption to traffic and sewage. The run of pipes would only be out of action for around 36 hours whilst the pipes were cleaned, any roots removed, and areas of damaged pipe made as circular as possible. Following this, a self-curing polymer coating would be applied along the full length of the run – and all of this would be done in one continuous operation.

David said:

“The advantage of this system compared to the “sleeve” system used by other companies was that any joining pipes self-benched, removing the necessity of having to cut into the new pipe liner. Additionally, once the polymer was cured, the new structure was completely self-standing, having used the existing pipes only as a mould.

“The only disadvantages were mainly that the pipe diameter was reduced by 20-25 mm because of the thickness of the material.”

Field trials were conducted on live sewer systems based on payment by success.

Several trials were done with varying degrees of success – with the most successful repair being on a 125m run of pipes.

Patents were obtained for the application head design and other aspects of the machine but unfortunately development halted before the machine could be brought to market.

David continued:

“The work on this system, involving developing the equipment, the lining materials, testing to find the optimal application conditions and settings within a very small enterprise, was challenging and perhaps over-ambitious. We developed a completely new, innovative integrated product which met a specific need and would today continue to answer that need had it been taken through to completion.”