A service you can rely on

Customers expect a reliable gas service, with few interruptions to supply. They also expect us to deliver network improvements in an efficient and considerate way, by minimising problems for motorists, local residents and businesses.

New technology, such as microphones we can send down pipes to listen for leaks, and giant road coring machines which reduce the size and number of holes we need to dig, helped to speed up jobs and save money in 2015/16.


We also improved our quality assurance processes, by beaming photos and video back to base for review by managers, and introducing a new quality control system for every pipe we weld.

There were challenges, however. The number of interruptions to our customers’ gas supplies due to planned work on the network was higher than we had targeted for the year. This was partly due to an increase in the number of service pipe renewals in 2015/16. On the plus side, we did manage to get these customers back on gas speedily, beating targets for gas restoration.

Unfortunately, there are some things we can’t control. A combination of atrocious weather and third party damage in 2015 took a toll on our network – increasing the number of unplanned interruptions to supply. Our teams worked round the clock to deal with these issues, and our customers were brilliantly understanding.

Outputs – a detailed look

This table takes a detailed look at our reliability performance in 2015/16. Simply click the plus arrow to read a brief commentary on what the statistic means, and how we did.

Output Target 2013/2014 Performance 2014/2015 Performance 2015/2016 Performance Status
Loss of supply
Number of planned interruptions 50,448 43,276 57,434 58,925 Behind

Interruptions to the gas supply for which customers were given prior notice. Planned mains replacement work is the most common scenario here. The stats show that the number of planned interruptions was higher than our target for the year – this is largely because of an increase in service pipe renewals.

Number of unplanned interruptions 8,408 11,464 13,034 14,289 Behind

Interruptions to the gas supply caused by unplanned issues – such as gas leaks, or water finding its way into the pipe network. Our performance was behind the annual target. Major factors were the atrocious weather at the start of 2016, and some serious water ingress incidents, which impacted our network. We are unlikely to hit our overall RIIO target, but will significantly reduce the duration of these interruptions.

Duration of planned interruptions (minutes) 27.3 million 22.4 million 30.3 million 13.7 million Ahead

The length of time the gas went off due to planned work, such as mains replacement jobs. We were considerably ahead of our annual target in 2015/16 – due to more efficient ways of working, use of new technology and better planning.

Duration of unplanned interruptions (minutes) 7.8 million 4.8 million 4.2 million 4.4 million Ahead

The length of time the gas went off due to unplanned issues, such as gas leaks. We were well ahead of target in 2015/16. This was great news for customers, as it meant reduced disruption. Use of new technology and the efforts of our emergency teams contributed to this strong performance.

Network capacity
Meeting NGN’s 1 in 20 planning standard (MWh pa) 512,701 500,315 502, 916 492,560 Ahead

This output requires our network to have enough capacity to ensure customers’ gas supplies are not interrupted during periods of highest demand (known as a 1 in 20 year event). Estimates of peak demand have actually been falling since 2005, and we comfortably outperformed our annual target.

PRI utilisation and capacity Phased plan Phased plan On target On target On target

Pressure Reduction Installations (PRI) reduce the pressure of gas before it is distributed to homes and businesses. To meet our obligations, assets need to be technically compliant and able to meet required volumes. We carry out a full analysis of PRIs and offtake sites using specialist modelling to determine the level of investment required.

Network reliability – maintaining operation performance
% by volume of network meter errors <0.1% pa <0.002% 0.0% 0.0% Ahead

We are responsible for monitoring and reporting the accuracy of the meters we use to measure the movement of gas from the National Transmission System into our network. We beat our annual target.

Number and duration of telemetered faults 196 105 63 135 Ahead

This target covers our response to telemetry faults (i.e. faults on equipment used to measure and record key data) on our above ground assets. In 2015/16, we had 135 faults against a target of 181.

Pressure System Safety Regulation Faults 0.51pa 0.43 0.26 0.31 Ahead

Statutory inspections are carried out on our network. We achieved 0.31 faults per inspection in 2015/16, outperforming our target.

Gasholder decommissioning 2 1 2 3 Ahead

We are in the process of decommissioning the region’s remaining 44 gas holders. These holders are a legacy of a different age and are no longer needed due to improvements in our network. We aim to demolish them all over a 16 year period. We completed the decommissioning of three holders in 2015/16 – one more than in our original plan.

The future

We’ll be ramping up our programme to dismantle our regions gas holders. These giant structures from another time are now obsolete. We plan to remove five holders from our network in 2016/17 to get well ahead of our phased target.

We’ll also be focusing on new ways to get customers back on gas as quickly as possible when they experience an interruption to their supply and will be exploring opportunities to minimise the impact caused.