Case Studies: No-Dig Pipe Repair
Rainwater Drainage at BAe Systems' Typhoon Fighter Hangars

10/12/2008

Prior to the job, we discussed the alternatives to this repair system, which involved the complete renewal of the defective pipes at the unrealistic cost of nearly £9,000.

We were told there were numerous leaking joints in the DN225 PVC pipe, responsible for rainwater drainage from the vast multi-apexed roof. These drainage pipes were situated in the root of each apex.

The large surface area of the roof meant each of these pipes carried a enormous volume of water when it rained, and the fact that the repairs necessary were on a vertical pipe added further complications.

The PVC pipes passed through a mezzanine walkway, which served to connect the various offices, conference rooms and admin areas. It was this mezzanine walkway that provided us with a stable platform from which to affect the repairs.

Firstly, a section of the PVC pipe had to be removed with a handsaw, to allow insertion of the Pipe Doctor packer. We had to ensure the pipe above the cut was supported as of course we certainly didn't want the weight of the pipe to pull the roof down from above!

The packer was pre-inflated to approximately 15mm less than the internal diameter of the pipe and a trial insertion was carried out.

Using a Pipe Doctor Repair Kit (PD225W Kit), the wetted out fibreglass mat was wrapped around the pre-inflated packer, and secured using copper shear-wire. It was then lowered down the pipe with a piece of rope.
Although there was a certain amount of water still passing through the pipe this would have no adverse affect whatsoever on the curing of the patch. Unlike other repair systems on the market, the Fernco Pipe Doctor cures fully, and properly, in pipes which may be flowing at full bore.

Once the packer, with its repair patch, was at the correct position, the rope was securely anchored, and the airline and pressure regulator were attached to the last visible air push-rod and then to the air compressor. The packer was fully inflated and left to cure in place for 1 hour.

Once the cure time had been reached, the air was vented from the packer and the packer removed from the pipe. A CCTV Survey showed that the repair had been completely successful.

The previously removed section of pipe was replaced and resealed using Standard Couplings from Flexseal and the drainage pipe was returned to a serviceable condition.
The ease, speed and lower cost of the Fernco Pipe Doctor repair seemed the obvious option.

Works carried out under guidance of Tony Hickman, Product Development Manager at Flexseal.