A flange plate on a 1800mm steel pipe is sealed and repaired after suffering tree root ingress

Wastewater Treatment Plant Seal Pipe Flange Against Tree Root Ingress

A wastewater treatment plant seal and protect a flange on a 1800mm underground pipe connected to a chlorine contact tank after the line was discovered to have been penetrated by tree root ingress between plates.

Case Study Overview

Site Wastewater treatment plant
Location United Kingdom
Pipe Type 1800mm steel pipe
Repair Type Leak repair
Products Wrap & Seal Pipe Burst Tape, SylWrap Pipe Repair Bandage

Pipe Defect

The steel pipe brought wastewater to a chlorine contact tank for the final stage of the cleansing process, known as tertiary treatment. This involves introducing chlorine to remove harmful pathogens which cause diseases including cholera, polio and typhoid.

A significant reduction in the performance of the tank led to the plant excavating the line to identify what was causing the issue. It was discovered that a tree root had managed to penetrate between two flange plates.

This had created three problems. The pipe was now weeping through the flange; there was a partial blockage of the line; and water which had undergone most of the wastewater treatment process was now being potentially re-contaminated.

Once the plant had removed the root from the pipe, they needed to seal the leak caused by the tree and protect the flange against future ingress.

SylWrap Solution

Because the flange was 100mm wide, there was enough surface area to repair and reinforce using the normal SylWrap method for a live leak repair. Wrap & Seal Pipe Burst Tape was wrapped around the point where the flange plates connected.

Several Wrap & Seals were applied on top of each other, with the self-amalgamating silicone fusing together to form a solid rubber band.

The application of Wrap & Seal continued until no more water was escaping from the pipe, indicating that enough pressure resistance had been built to seal the leak.

To protect against future tree root ingress, the flange was wrapped in SylWrap Pipe Repair Bandage. A SYL412HD Bandage was used as its 100mm width meant it fitted perfectly over the flange plates.

SylWrap Bandage was activated using water and wrapped and smoothed around the flange. Within minutes, it had cured to form a rock-hard protective shell. This reinforced the initial leak repair and ensured the line could not be penetrated again through the weak spot between flange plates.


Completing the repair took under one hour. The plant was able to remain fully operational whilst the application took place. Had the flange needed replacing, the site would have faced a challenging and time-consuming project involving draining the tank and isolating the line.

Once pipe had been sealed, the line was reburied. The plant now had confidence that it would take a monumental effort from a tree to force its way between the flange plates in future.

Follow Up

The company operating the plant were grateful for the technical assistance provided by Sylmasta in formulating a repair method for what had initially looked a complex application, given the well-known challenges with sealing leaking flanges.

They were equally impressed by the speed of the application, which caused minimal disruption to processes on site and the treatment of customer wastewater.

Products Used

Wrap & Seal Pipe Burst Tape
Silicone tape which fuses into a solid rubber band to create a high pressure seal

SylWrap Pipe Repair Bandage
Water-activated wrap sets rock hard to create a protective sleeve over repairs

Universal Pipe Repair Kit
Wrap & Seal and SylWrap Bandage are supplied in a Universal Pipe Repair Kit

Pipe Repair Contractor Case
Contains enough Wrap & Seal and SylWrap Bandage to make up to six live leak repairs

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