Case Study: Protection of Underwater Gas Pipe Network Laid Through River System

Case Study Data

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Site
River network
Location
Scotland
Repair Type
Pipe reinforcement
Defect
Exposed gas pipes in rivers left vulnerable to impact damage

Products Used

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SylWrap HD Pipe Repair Bandage
Composite repair wrap applied to submerged pipes which set rock-hard to form an impact resistant outer layer 6mm thick

Case Study PDF

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Case Study Details

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Large sections of the gas pipe network in Scotland run through river and stream beds. Whilst these pipes are well buried during installation, changing conditions within waterways can still lead to exposure by riverbed scour and erosion.

Riverbed scour occurs when gravel, sand and rocks are washed away by fast-flowing water. The problem is intensified during floods, where rising water levels increase the speed of rivers and streams.

With climate change making extreme weather events more frequent, Scottish gas distribution company SGN have seen a sharp rise in the number of riverbed pipes on their network becoming exposed.

This poses a serious challenge. Without the covering and protection provided by the gravel and sediment of the riverbed, pipes are left open to impact from other debris carried by the water.

Such exposure increases the chances of surface damage which weakens the pipeline. Enough damage over time or from one big impact with a heavy object leaves the pipe at risk of being breached.

The problem of exposed pipes in riverbeds shows no signs of going away. Winter rainfall levels in Scotland increased by 19 percent in a decade between 2010-2019 compared to 1961-1990.

Knowing even more of their gas network will become exposed by riverbed scour in future years, SGN contacted Sylmasta looking for a protection method which could be applied to any submerged pipe in any river across Scotland.

Sylmasta recommended the use of SylWrap HD Pipe Repair Bandage. SylWrap HD is a composite wrap with a water-activated resin which sets rock hard in minutes to form an impact resistant protective sleeve around pipework.

Before SylWrap HD could be used on the gas network, it had to receive several approvals from relevant industry bodies. This was handled by SGN with the process fast tracked through the system because of the importance of the project.

SylWrap HD also had to receive authorisation from the Scottish Environment Protection Agency before it could be used in natural waterways. SEPA tested SylWrap to ensure it would not impact or pollute the environment in any way.

Sylmasta then flew to Scotland to provide technical support for SGN with initial trial repairs, made to an exposed pipe in a shallow river around one-metre deep.

Contractors entered the water and applied SYL616HD Bandages along the entire length of gas pipe. As soon as SylWrap HD was submerged, the resin began working.

The contractor worked quickly to wrap the bandage in a six layer repair. SylWrap HD easily cured underwater within minutes. Once set, it formed a 6mm thick shell protecting the pipe against future impact damage.

Several different exposed pipes ended up being protected with SylWrap HD during the trial, including one in an area where visibility was made difficult due to reeds from a bank. At one point, a number of fish even swam around a newly-wrapped pipe to see what was going on.

SylWrap HD posed no danger to those fish or any other wildlife living in the river, as certified by SEPA. The bandage also has WRAS approval, meaning it has been approved as safe to use on pipes carrying drinking water.

After the trial, one SGN contractor described working with SylWrap HD as “an absolute dream”. SGN were particularly pleased with how quick and easy SylWrap is to apply, as it would allow them to cover potentially hundreds of kilometres of pipework at a fast rate compared with alternative products.

SGN subsequently ordered over 500 SYL633HD Bandages for the river pipe protection programme to start immediately, helping to maintain the integrity of the Scottish gas network for years to come.