Posted: 8 June 2017
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Mini innovation, maximum impact

Gas Transmission’s Innovation Value Mid-Term Report looks at how new ideas transform into real value for customers. One project is helping the business make six-figure savings – and reinforcing the security of our gas network – through corrosion prevention technology. Michael Chenery, Lead Project Manager, Site Campaigns, tells us more about MiniLog and the problem it’s successfully solving.

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Mini innovation, maximum impact

Mini innovation, maximum impact

MiniLog is helping NGGT generate reliable data about the effectiveness of its corrosion prevention technology.

“The MiniLog provides definitive confidence that corrosion prevention technology is working on a pipeline, reducing the risk of error from human interpretation, and allowing for more defects to be safely closed”

Michael Chenery, Lead Project Manager, Site Campaigns.


£144k – of cost savings made to date

Source: National Grid.

The secure flow of gas across the UK’s transmission network depends on keeping our pipelines in good condition. We prevent corrosion of the metal surface of these pipes by using a technique called Cathodic Protection (CP).

Michael Chenery, Lead Project Manager, Site Campaigns.

It’s a technique that’s widely used to protect all kinds of metals, from ships, to offshore oil platforms and, in our case, pipelines. It works by connecting the pipeline surface to a more easily corroded metal, which we call the sacrificial metal.

An electrical current is applied and the sacrificial metal becomes corroded in place of the pipe itself. It’s a very effective method for helping maintain the integrity and reliability of our pipelines over time.

Like any technology, it’s important we test these CP systems regularly to make sure they’re working effectively. Traditionally, we’ve assessed this by measuring the pipe-to-soil potential at various intervals along entire sections of pipeline.

Science of soil

Pipe to soil potential data indicates where CP is ineffective and/or corrosion hot spots, and enables remedial work to be focused on such areas.

The issue we’ve faced is that stray currents, such as those from overhead wires or even train signals, can affect our readings. When that happens, we have to log the incident as a potential defect, even though we’re fairly confident a stray current has caused the anomaly.

This triggers a long and expensive investigation process involving follow-up surveys, excavation and the installation of probes. It also relies heavily on the interpretation of experts, which leaves the process open to a degree of human error.

Solving the problem

A brand new innovation, called the MiniLog Stray Current Monitoring Device – funded through the Network Innovation Allowance (NIA) – is transforming this process. And already delivering impressive cost savings and greater security of supply.

MiniLog rapidly switches the electrical connection to the pipe on and off, logging data over a 48hr period. This allows all the different daily influences, such as stray currents, to be reliably captured.

The MiniLog is already delivering impressive cost savings and greater security of supply.

Another key part of the innovation is that the MiniLog connects to a small piece of metal (called a coupon), which is electrically connected to the pipe itself. By testing this smaller metal – rather than the much larger pipe – we can actually eliminate the effect of the stray current. These things combined give us an enhanced pool of data that more accurately measures the effectiveness of CP.

As a direct result of testing with MiniLog, our previous need for re-surveying and expensive, high-risk excavation is successfully avoided – and more stray current defects can be quickly and safely closed.

What’s more, our technicians no longer need to travel to several locations along a pipeline to take readings. Instead they visit each site just twice. Once to fit the device into the test post – and once to retrieve it at the end of the test period.

Impressive results

We’ve now invested in eight MiniLog devices and have six technicians who are trained to use them.

The technology has already allowed us to quickly close 12 stray current defects, which would otherwise have been subject to expensive investigation work, generating a saving of £144k.

We’ve identified 86 existing defects where MiniLog can be used very soon, so the benefits will continue to multiply as we move forward.

Fast facts

16 – the number of stray current defects safely closed

£144k – of cost savings made to date

Read more:

To find out more out Gas Transmission’s innovation portfolio – and how it’s benefiting our customers – read our Mid-term Innovation Value Report.

  • Alan Coates

    This is a great story!

  • Alan Coates

    This is a great read!

Gas innovation in full flow