Piping up for savings

A technique for internal pipe repair is making savings on major United Utilities mains projects. Intrepid WWT editor Natasha Wiseman dropped into the pipe to find out how it works

A pipe repair on the Haweswater Aqueduct is just routine for PMP Pipelines, but it has saved United Utilities (UU) as much as £250,000 in civils costs for pipe replacement. The four-pipe aqueduct carries drinking water supplies from Haweswater reservoir in the Lake District to the main supply for Manchester.

Construction was completed in 1955 and metal pedestrian access gates through field boundaries mark the line of the pipeline for inspectors who regularly walked the 134km pipeline before the days of aerial surveying. Joint repair specialist Planned Maintenance (Pennine) (PMP) has undertaken a range of work on UU’s major aqueduct restoration projects in recent years.

Like much of UU’s network, the Haweswater line is gravity fed and the leak was occurring after the water left a valve house near Kirkby Lonsdale in Cumbria. On identifying the breach on one of the pipes, PMP undertook the repair internally, shutting the valves and relying on the remaining pipes to maintain supplies.

The leak was occurring where a steel pipe carrying the flow down a steep hill joined the pre-stressed concrete pipe that makes up some 90% of the aqueduct. According to PMP, one of the toughest challenges for trenchless pipeline rehabilitation arises when making connections between different pipe materials.

In this instance, the PMP operative entered the pipe at the valve house to fit the AMEX-10 Seal at the pipe joint from inside the pipe. In situations where access can be gained by engineers trained in confined space working, the AMEX-10 seal can be installed internally.

The AMEX-10 is a low profile, mechanical seal for internal repair of leaking pipe joints.

A robust section of rubber that spans the joint is fitted using hydraulic expansion of stainless steel compression rings, thus eliminating the use of chemical adhesives and their associated hazards.

The EPDM rubber seal is able to accommodate substantial joint movement and is abrasion resistant. PMP says it has been independently verified for life expectancy of more than 50 years.

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