A heavily corroded pipe in a district heating system undergoes a leak repair to keep it operational

District Heating System Corroded Pipes Leak Repair

Heavy corrosion had caused breaches to pipes in a district heating system running through confined underground tunnels, leaving a local council needing a flexible pipe repair method to avoid shutting down the system to fit replacement parts in the depths of winter.

Case Study Overview

Site District heating system
Location Yorkshire, UK
Pipe Type Steel
Pressure 20 bar
Repair Type Leak repair
Products Wrap & Seal Pipe Burst Tape, SylWrap HD Pipe Repair Bandage

Pipe Defect

A combination of subsidence, damage caused by roadworks and underground flooding had led to corrosion causing two breaches in steel pipework carrying hot water as part of a district heating system in Yorkshire.

The pipework system supplied heat to council-owned homes via underground tunnels. One leak area was on a difficult welded joint; the other in a flooded ‘low spot’ of tunnel which effectively left that section of pipe underwater.

Access to the district heating system was severely restricted, ruling out the use of pipe repair clamps because of their lack of manoeuvrability.

Shutting the system down to replace the damaged sections was not an option as it would have left residents without heat for several days.

The council needed a flexible repair method to seal the leaks and protect the pipework from further damage until a replacement could be carried out once Spring and warmer weather arrived.

Entrance to the underground district heating system
Access was too restricted for bulk repair solutions
Heavily corroded steel pipe in a district heating system requiring a live leak repair
Heavily corroded steel pipe needing repair
Welded joint on a steel pipe requiring a live leak repair in a district heating system
Leak section around a welded joint

SylWrap Solution

Wrap & Seal Pipe Burst Tape was used to seal the two breaches in the district heating system pipework. Wrap & Seal is made from self-amalgamating silicone and stretches by 300 percent to fuse into a solid rubber band, creating a high pressure seal over leak areas.

Once Wrap & Seal had successfully sealed the leaks in the pipework, it was overwrapped with SylWrap HD Pipe Repair Bandage. SylWrap HD is a composite repair wrap with a water activated resin which sets rock hard over pipework in minutes, providing an impact resistant shell.

Reinforcing the district heating system with SylWrap HD protected and strengthened the pipe from future damage caused by corrosion, building or maintenance works, or continued flooding of the tunnel.

This was particularly important as the existing underwater low spot had seen several inches of insulation material eaten away via water damage, something which SylWrap HD would now protect against.

Both Wrap & Seal Pipe and SylWrap HD are temperature resistant to 200°C and pressure resistant to 30 bar, making them suitable for repair of any pipework in a district heating system.

Corroded pipe repair of steel pipe in a district heating system
Successful repair of first section of corroded pipe
SylWrap pipe repair carried out to a leaking steel pipe in a district heating system
Welded joint repair completed with SylWrap HD


Despite the space constraints from working in underground tunnels, Wrap & Seal and SylWrap HD were both wrapped effectively around the district heating system pipework.

The two damaged sections were successfully repaired without any disruption to the heating supply of the council owned properties.

Although the council were only looking for a temporary repair to keep the system operational until it could be replaced, repairs made with SylWrap are permanent.

Should the council wish, they could therefore indefinitely delay their plans for a Spring replacement, potentially saving significant costs along the way.

Follow Up

Most district heating systems in the United Kingdom were installed in the 1960s and 1970s with a 50-year guarantee, meaning many are now starting to reach the end of their lifespans.

District heating repairs are therefore becoming more commonplace for local councils and facilities management companies responsible for such systems.

Sylmasta recommended to the local council that they take stock of the SylWrap Pipe Repair Contractor Case which would allow their teams to make up to six live leak repairs as soon as leaks and bursts are detected.

The Case is easy-to-store on the van and no formal training is needed to carry out a repair; simply reach for the products inside and follow the instructions provided to return a district heating system to full working order. It could also be used on any other type of pipe the council are responsible for.

Products Used

Wrap & Seal Pipe Burst Tape
Self-fusing silicone pipe repair tape, seals live leaks, temperature resistant to 200°C

SylWrap HD Bandage
Water-activated wrap sets rock hard to reinforce, protect and strengthen pipework

Universal Pipe Repair Kit
Wrap & Seal and SylWrap HD can be purchased together in a Universal Pipe Repair Kit

Pipe Repair Contractor Case
Easy-to-store case with everything needed to make up to six emergency pipe repairs

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