Case Study Overview

Site Terraced cottages
Location London, UK
Repair Type Leak repair and pipe reinforcement
Defect Heavily corroded 48-metre-long steel shared water supply pipe breached in places

Repair Products

Superfast Aqua PW Epoxy Putty, Liquid Metal Epoxy Coating,
SylWrap Pipe Repair Bandage

Case Study PDF

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Case Study Details

The row of eight terraced cottages were built in the middle of the 19th century. They were connected to the public water network at a later date, which led to a somewhat unusual setup involving an above-ground shared supply pipe.

This steel pipe connected with a water main underground at one end of the terrace. It rose up the side of the first cottage and was then fixed at a height of around three metres to the back wall of all eight properties, along which it ran for 48 metres.

The height of the line meant it was surrounded by extensions built onto the cottages, downpipes, guttering and other installations and improvements added to the buildings over time. Access to certain sections was therefore severely restricted.

Each cottage was responsible for the section of pipe outside their property, giving them around six metres to maintain and upkeep. Lagging had been added around all 48 metres of the line to protect it during winter.

Unfortunately, low-quality insulation material was used which soaked up moisture like a sponge, causing water and condensation to become trapped against the steel. Over time, this led to heavy corrosion and a weakening of the pipe.

When temperatures in London dropped as low as -8°C in an unusually cold spell and water inside the pipe froze, the brittle metalwork was unable to cope. Several cracks appeared outside one cottage, requiring repair.

The lagging was removed from the leaking section to access the pipe, at which point the extent of the corrosion problem became clear. The other seven cottages were inevitably going to suffer from bursts on their sections in future if something were not done.

Initially, the cottages contacted their water company for help. Because the pipe was a shared supply line and not part of the public network, the water company said they had no responsibility for it. It was therefore down to the eight property owners to find a solution themselves.

The cottages were quoted £22,000 to replace the entire line. Some of the property owners did not wish to contribute £2,750 towards the cost, preferring instead to take a chance their section would not burst.

It next became clear that replacing individual sections of pipe for those cottages wanting to avoid future leaks would not be practical either. New fittings would struggle to connect with old, brittle pipes not being replaced.

Installation would also be disruptive to those cottages not undertaking work, with shared electrical boxes and satellite dishes having to be taken out of service whilst new sections of pipe were fitted.

With no common route forward found, the cottage with the leaking section contacted Sylmasta for advice on sealing the holes on their part of the line. At this point, the owner also explained the complications caused by the shared water supply pipe and the concern about how it might deteriorate further.

Sylmasta suggested that in addition to sealing the cracked section of pipe outside one cottage, their Pipe Refurbishment System be used to reinforce individual sections along the line for those property owners wanting protection against future leaks.

Two cottages requested their sections be attended to, and so Sylmasta sent an approved contractor to London to carry out the repair and strengthening of the shared water supply pipe.

Once the lagging had been removed, the first stage of the Pipe Refurbishment System involved application of the leak sealant – in this case, Superfast Aqua PW Epoxy Putty.

Superfast Aqua PW was chosen for its excellent wet surface adhesion to alleviate concerns the pipe may have been weeping water. It has WRAS approval, meaning it is certified as safe to come into contact with potable water.

Aqua PW is supplied in a pre-measured 114g stick. The required amount of putty was cut from the stick, kneaded by hand and then pushed into the cracks and damage in the pipe whilst soft. Within 20 minutes, it cured to form a rock-hard sealing material.

The second stage of the Pipe Refurbishment System saw Liquid Metal Epoxy Coating applied to strengthen the line and protect it from corrosion. Liquid Metal was painted on by brush to sections of the pipe outside every cottage who wanted their part of the line reinforced.

Once cured, Liquid Metal formed a smooth, metallic, hard-wearing outer surface around the pipe to act as a shield against external corrosion. Should the brittle steel be breached from the inside by freezing temperatures in future, the Liquid Metal shell will contain the contents of the pipe.

SylWrap Pipe Repair Bandage was added as the final stage of the Pipe Refurbishment System, to provide the shared water supply pipe with another layer of protection. SylWrap HD is a composite repair wrap with a water-activated resin which sets rock-hard in minutes when wrapped and smoothed around pipework.

Nine SylWrap Bandages were applied per cottage to build up thickness to four layers, with the application taking place whilst the Liquid Metal remained tacky to improve adhesion to the pipe. Once cured, SylWrap HD formed an impact resistant shell encompassing the pipe.

In addition to the two planned repairs, a third cottage owner asked for their section to be reinforced, having seen how straightforward and cost-effective the process was. Their part of the shared water supply pipe had not been as badly weakened by corrosion and therefore required only Liquid Metal for suitable strengthening.

All three cottages were completed in a single day, with the approved contractor also installing new lagging to replace the original insulation which had to be removed. A fourth cottage then requested the approved contractor return and attend to their part of the pipe, meaning half the 48 metres had been reinforced.

Around one year after the original repair and a fifth cottage contacted Sylmasta. 12 months of further corrosion had left their section of the pipe on the verge of collapse.

Refurbishment of this section was now far more challenging and costly than the repair the other four cottages had opted for – highlighting the benefits of strengthening and protecting systems before more serious problems develop.

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Products Used

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