A dilapidated, corrosion-covered 300mm steel pipe crossing a 20-metre long bridge over the Rhonda River undergoes repair and refurbishment, helping to save Dwr Cymru Welsh Water from carrying out an expensive replacement of the severely weakened structure.

Case Study Overview

Site Pipe bridge
Location Porth, South Wales
Pipe Type 300mm diameter, 20-metre long steel pipe
Repair Type Leak repair and pipe refurbishment
Products Liquid Metal Epoxy Coating, SylWrap CR Corrosion Protection Wrap

Pipe Defect

Sylmasta were contacted by Dwr Cymru for advice on repairing and extending the lifespan of a pipe bridge they operated, crossing the Rhonda River in Porth, South Wales.

Dwr Cymru favoured refurbishment because of the complexities involved in replacement. Amongst the issues they faced were securing Network Rail permits for removing a section of pipe passing under an adjacent railway line.

A flood risk assessment and permit from the Environment Agency were also required, along with redirection of flow during replacement, fabrication of a new pipe and safe disposal of the existing corroded line. The total cost was estimated at over £200,000.

The bridge was gravity fed and made up of a 300mm, 20-metre long steel pipe rested inside an angle-iron structure for support and protection.

It was recommended the four-stage Sylmasta Pipe Refurbishment System be used as a starting point. A final decision on the repair elements required would be made once the pipe had been fully inspected.

Dwr Cymru appointed Arch Services of Porth for the project, with Sylmasta providing technical expertise. The inspection carried out by Arch revealed the pipe to be completely corroded. This had eaten through the steel in several places along the top of the pipe, leaving large holes.

To repair and refurbish the structure, all of these holes had to be sealed followed by the reinforcement of the entire line, which had been left severely weakened by the heavy corrosion.

SylWrap Solution

The holes were too big and the pipe too brittle to be repaired with epoxy putty, so Arch used large fibreglass patches layered over the cracked sections to seal the leaks. The entire pipe was then coated with Liquid Metal Epoxy Coating.

Liquid Metal is a metal-filled, brushable epoxy. Several layers 1mm – 2mm in thickness were applied to the pipe using a roller. Once cured, Liquid Metal formed a hard-wearing, smooth, metallic surface around the outside of the pipe.

This new outer impermeable skin would prevent further corrosion and ensure no more fluid could escape. Liquid Metal was also painted onto the corroded steel hoops and beams holding the pipe in place, refurbishing the entire structure.

The 90 minute gel time of Liquid Metal allowed large amounts of coating to be mixed and applied without the threat of premature curing. To further reinforce the pipe and reinstate its integral strength, the line was wrapped with SylWrap CR Corrosion Protection Wrap.

SylWrap CR is a composite repair bandage incorporated with highly effective corrosion inhibitors. It has been specially formulated to protect pipes, metalwork and other structures against corrosion in harsh and aggressive environments.

Four layers of SylWrap CR were applied to the pipe, the first layer being wrapped whilst the final coating of Liquid Metal remained tacky. The resin in SylWrap CR was activated with water and the bandage tightly wrapped and smoothed around the pipe.

Within minutes, SylWrap CR cured to form a rock-hard, impact resistant shell. Arch were particularly careful in ensuring that no area of the pipe was left without SylWrap CR coverage. This required precise application close to the steel hoops.

Outcome

The repair took three days compared with the one-month estimated completion time of replacement. Once finished, the final result was a very smart pipe bridge now protected from future corrosion and reinforced against breaches by Liquid Metal and SylWrap CR.

Repairing and strengthening the pipe bridge cost under £12,000 and prevented Dwr Cymru from having to undertake a very complex replacement. They were happy with the speed and ease with which Arch carried out the application.

Follow Up

Arch Services have subsequently become Sylmasta’s approved contractor for similar projects in the region after their excellent documentation of the process and attention to detail.

Products Used

Liquid Metal
Epoxy coating used to refurbish pipes and structures by forming a new metallic surface

SylWrap CR Wrap
Repair bandage with corrosion inhibitors for protecting pipes in harsh environments

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