Statistical process control – making it work for the gas transportation business

Transco is the main provider of gas transportation to domestic and commercial customers in mainland Britain. Gas arrives in Britain at a steady rate but it consumed with a distinct diurnal pattern. The safe and timely movement of gas from arrival at the beach in various places in Britain to delivery at burners is the main driver for System Operations. The movement of gas is meticulously controlled and monitored resulting in a mass of information on pressure, flow and temperature. Gas is stored temporarily in various storage vessels and is moved around the pipes and in and out of storage as demand dictates. Demand is mostly dictated by the weather and is therefore subject to much variation. Transco and its predecessors have been transporting gas for over 50 years and are very successful as judged by their excellent safety record and the continual delivery of gas. Nevertheless, the company wishes to improve itself and make further use of the many measurements collected. SPC is ideal for improving communication and understanding through increased visibility of data. All companies have special issues to face when they implement SPC, and this paper decribes the way these were dealt with in System Operations and the lessons learnt along the way. The first part describes how performance measures were chosen for investigation. It includes a novel use of correlation between output and day-to-day conditions, which was successfully turned into a measure to check the uncheckable. The second part is about the issues involved with early application of SPC when features of the system are still unexplained. SPC has helped enhance understanding of the complex transportation process, encouraged team work, improved performance and provided an objective means of decision making.