New lease on life for the Castle of Good Hope

Nu Flow’s Structural Pull-in-Place liners is a non-invasive technology that allows for the downpipes to be repaired without causing structural damage.

By Kelly-Ann Prinsloo

When the Castle of Good Hope, a national landmark, needed new pipes, Water Damage Services had the perfect solution.

Water Damage Services, a licensed Nu Flow installer, met with the City of Cape Town to discuss the rehabilitation project currently underway by GVK Siya Zama Construction. The company was called in as an independent consultant to assess the Castle’s stormwater facilities; water leaked into the heritage site every time it rained, which not only affected the painted walls and finishings, but also caused long-term structural damage to the heritage site.

The first step forward was to complete a full CCTV camera survey on the downpipes, to inspect the condition of the lines and determine the best possible repair solution.

Extensive high-pressure cleaning and specialised drilling with micro cutting equipment was completed on 125 downpipes to remove blockages, scale, cement and building rubble from the lines. Once this was complete, CCTV camera inspections were conducted.


Once the epoxy has cured, the rubber bladder is removed leaving behind a ‘nu pipe’ within the host pipe.


Water Damage Services found that the bulk of the stormwater pipes were 80mm steel fabricated down pipes, made of mainly mild steel approximately 2mm thick. At the time of construction, these pipes were formed by means of bending sheet metal in to a square shape before welding a long seam down the length as a join. All the 90-degree and 45-degree fittings were manufactured using the same method as detailed above.

During the inspection, Water Damage Services found that most of the welds holding the joins and seams of the pipes together had corroded, resulting in poor and compromised joins that resulted in water leaking through into the surrounding structures.

The generic problems found throughout the stormwater system were blocked pipes, disjointed and comprised joins, and pipes that had been inserted against the flow of water.

It became clear that traditional pipe replacement would cause irreparable damage to the historic building’s walls and paving, which have stood as they are now since 1679.

Water Damage Services advised that the best way forward was to reline the pipes using Nu Flow’s Structural Pull-in-Place liners, a non-invasive technology that allows for the downpipes to be repaired without causing damage to the heritage site.

The relining project was approved, and Water Damage Services commenced the work in November 2015 and successfully relined 1 203m of 80mm and 110mm square steel down pipes. The pipes were first cleaned and descaled using Nu Flow’s unique micro-cutter, which drives a drive shift cable with tungsten carbide tipped cleaning balls on the end.

Once the pipes were descaled and returned to their full diameter, the pipes were lined with Nu Flow’s structural lining technology. A felt sleeve is impregnated in epoxy and pulled into the problematic host pipe. Within the liner is a rubber bladder which is inflated when the liner is in the correct position. The bladder is left inflated while the epoxy cures. Once the epoxy has cured, the rubber bladder is removed, leaving behind a ‘nu pipe’ within the host pipe.

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