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NETWORK / 25 / FEBRUARY 2017 2 Impact of seismic analysis on towers, equipment, structures NNGET – completed The preparation phase of Grade 4 tower steelwork (G4T) involves the use of hand- held, powered wire brushes to remove old paintwork and surface rust. This produces debris, which has been identi ed as an issue in sensitive environments, such as near waterways or housing. A total of 20 towers scheduled for repainting are close to such sensitive environments. This pro- ject sought to evaluate three approaches – debris netting, hand-held vacuum, and industrial vacuum with manifold system – for the mitigation of the e ects of cleaning structural work. Of the three options, only the hand-held vacuum and netting have been taken for- ward because of concerns about the practi- cality and safety of the industrial vacuum. The hand-held vacuum unit was trialled suc- cessfully on the tower steelwork on the 4ZO This project will attempt to use cognitive technology to capture knowledge about the 7,500km of pipeline and assets on the gas transmission system held by a wide range of sources. A number of routine, complex and critical processes depend on the inter- pretation of this knowledge by individuals. That knowledge is spread across more than 600 technical standards and held by an ageing workforce, with a number of techni- cal experts due to retire. Current methods of employees shadowing experts for up to a year are ine‡ cient and do not ensure the complete transfer of knowledge. Cognitive technology will provide a tangible and intelligent method to inter- rogate this knowledge in a timely, e ective and consistent manner. There are at least 60 recognised technical specialists who spend beween 20% and 40% of their time This project questioned whether overhead line tower and substation support struc- tures built to current design speci cations can withstand the largest earthquake likely in the UK. The study also explored whether there are any implications from lower-inten- sity, higher-frequency seismic activity of the type that might be induced by fracking activities. A review of current developments in fracking was undertaken and a representa- tive seismic scenario from fracking activities modelled for support structures for trans- formers, gas-insulated substations, current transformers, voltage transformers and surge arrestors. Analysis revealed that the impact of fracking may not be signi cant. However, NGET will continue to review the e ects of fracking on a site-by-site basis. The seismic study showed that concrete structures were prone to collapse with a one in 2,500-year seismic event, but at a more credible one in 475-year event, the same structures would not collapse. As a result, there will be more guidance on the seismic design of UK electricity transmission struc- tures in the new Eurocode 8-compliant technical speci cations that NG will roll out during 2016. ENVIRONMENTAL CONTROL 1 1 Control of debris and dust from treatment of Grade 4 tower steelwork NGET – completed Cognitive technology for technical standards NGGT – launched route (through the Woodhead valley, east of Manchester) during 2015/16. Two units have been purchased and are being used and managed by the overhead line teams. It is a low-cost option that will be suitable in low-wind conditions for most towers. The debris netting may be the only viable solu- tion where towers are particularly close to housing or a water course. A trial is planned this summer to test whether painting work can be carried out within the netting framework. Three con- tractors will install the debris netting solu- tion, with National Grid performing a G4T and painting trial within the netted tower. If the trial is successful, it may be possible to paint towers that have previously been di‡ - cult or impossible to access because of their proximity to third-party properties. A˜ er the trial, a decision will be made on the most cost-e ective way to deploy this option to all overhead line routes across the NG network when repainting in environ- mentally sensitive areas. S M A R T E R W O R K I N G