FortisBC 36-Inch High Pressure Line Isolation Using Double Block and Bleed Technology

This paper discusses the benefit of using single-tap double block and bleed (DBB) technology to isolate large diameter (24-inch and 36-inch) natural gas transmission lines during tie-in of a pig launcher and receiver in Surrey, British Columbia, Canada. The pipeline, which is owned by FortisBC, is the only source of supply for the city of Coquitlam, the Vancouver Island system, and a major power generation facility. As such, shutting down the line was not an option. Instead, the project required a bypass. However, the footprint of the jobsite was too small for a traditional bypass. In addition, the jobsite’s location adjacent to a major highway and a tight timeline meant that first time isolation success was mandatory.