Pipe relining at Johannesburg Post Office Building

Johannesburg Post Office Building

The Johannesburg Post Office Building in Braamfontien was renovated prior to new tenants moving into the 10 story building. Part of the renovations was replacing old leaking corroded sewer pipes.

Contractors replaced the sewer pipes inside the building and some sections of piping on the outside of the building, but there were two long sections of piping that could not be replaced. This section of pipe is 6 meters deep running under the entrance to the basement parking of the High Court which was the first problem.

The second issue was that this section of sewer line has a large amount of other services (electric cables, fibre optic cables, water pipes and other unknown services) running above the sewer line. An attempt to replace this line would definitely result in other services been hit and damaged. This could not be excavated.

The contractors doing the plumbing work called Nu Flow to assist in relining the section of pipe that was irreplaceable.
The project presented a few challenges: The distance between manholes was very far with multiple 90 degree bends in the pipe line.

There was also a manhole in the middle of the section of pipe needing lining that had been covered over. Nu Flow installers needed access to this manhole as it was right by a junction with long distances of pipe on all 3 sides of the junction. Attempting to line without access to this manhole was risky. Nu Flow technical staff were adamant that the manhole needed to be located and exposed in order to ensure the project went smoothly.

Nu Flow technicians managed to locate the hidden manhole which was 6 meters deep using a sonde and pipe and cable locator. Exposing the manhole was a slow process as contractors had to dig carefully and ensure that no services were damaged. The contractors would dig a few meters deep and Nu Flow technicians would come back to site with a sonde and locator to verify the position of the covered manhole.

Once the manhole was finally exposed Nu Flow technicians began lining. 15 meters of 110mm sewer pipe and 50 meters of 160mm pipe was relined working from manholes thereby causing no damage to the Post Office building and no disruptions to the High Court’s day to day operations.

How it works:
An epoxy saturated liner is inserted into the pipe. Within the liner is an inflatable bladder.

When the liner is in the correct position the bladder is inflated and left inflated until the epoxy has cured.

Once the epoxy has hardened the bladder is removed leaving behind a “nu pipe” within the host pipe.

NO chopping open!
NO damage!
NO mess!

Download pdf of this case study

Read more Commercial case studies