STATS were required to isolate a 38” gas pipeline using a Remote Tecno Plug to facilitate the removal of a corroded 2” bypass branch connected to a 38” Emergency Shut Down Valve (ESDV). The 38” pipeline was operating at 85 barg and produced a gas service with 0.7% concentration of H2S. Prior to pigging the Remote Tecno Plug to the isolation position, a 38” high differential Bi-Di pig was deployed a distance of 1km to provide a water barrier between the Remote Tecno Plug and the pipeline gas.
During pigging operations the Tecno Plug position was tracked and confirmed using an extremely low frequency through-wall communication system. With the isolation confirmed, the operator then carried out the maintenance to remove and blind the 2” branch from the 38” ESDV. Before the Tecno Plug was unset and removed from the pipeline, the client required a pressure test of the modified line to confirm integrity. This was achieved by equalising the pipeline and receiver side pressures to 90 barg while the Tecno Plug remained in a fully ‘set’ condition. This reverse pressure test operation created a 90 barg test boundary to confirm the newly installed weld. With the maintenance successfully completed the Remote Tecno Plug and Bi-Di pig were reverse pigged back to the launcher and demobilised.
This successful project provided a safe and cost effective double block and bleed isolation, resulting in no interruption to plant production and preventing a costly shutdown. The safe and efficient workscope was a result of advanced planning, dedication and team work between STATS and client personnel.