After 6 months of planning the site and of course many years of developing the robotic platform, the first online trial of GRAID in ‘live’ gas conditions commenced. The plan was to survey the site pipework at Pannal Offtake located near Harrogate, Yorkshire for a period of 2 weeks. This would be a world’s first for this type of inspection and a key objective of GRAID to not interrupt the pressures or flow of gas on a site. The previous weeks had seen National Grid’s Pipeline Maintenance Centre (PMC) set up site ready for our arrival, ensuring all the equipment was in place and ready to start on Monday 18th June.
The 2-week inspection period flew by with the weather being especially kind considering a British Summer is never guaranteed! The objectives that the team set were all met and after the usual safety checks we found ourselves focusing on the first location of interest which were the above ground pipe supports. These areas have always been difficult to survey considering the costs relating to exposing the pipework underneath to check for corrosion. During the time we were on site the GRAID robot managed to carry out detailed scans on four pipe supports, potentially saving National Grid money even before going underground! The second and third locations was the transition between above and below ground and then the weld locations further into the pipework. In both examples the GRAID robot scanned and reporting back wall thickness measurements with ease. The furthest distance we travelled was around 60 metres into the National Transmission System and using the camera feeds on the robot could make out markings on the inside of the pipe and clearly see the weld locations. Another benefit was the ability to view the 30-inch Cameron Ball valve being operated from the inside of the pipe whilst at pressure – again another first for the project at transmission pressures.
Once GRAID was starting to provide data from the pipework it was an opportunity for Pipeline Integrity Engineers (PIE) to begin understanding what this meant for the overall condition model of the site. This stage allows the GRAID data to be used as a method of verifying the existing assumptions and allows extrapolation across a much large area than the robot has travelled. This work will continue long after the robot has been removed from site, but early indications show the data to be providing a fantastic insight into the condition of transmission pipework on site after 50 years.
During the survey period, we were visited by several different people all of whom had been involved along the way and it was a great opportunity for them to see how far we have come and gain an appreciation of the GRAID programme. Everyone left site with a much better idea of what GRAID was and more importantly how it could be used or developed further in the future. This is great for the team as the more people that discuss GRAID and how it could contribute to National Grid’s T2 discussions, the better.
A huge thank you to everyone who was involved in the survey, both past and present, we had a very successful 2 week stay at Pannal Offtake and not only achieved all the objectives but exceeded them! Next, we move into a few weeks of focusing on the wall thickness sensors ahead of our 2nd online trial in mid-August.