The FTL Pipeline was a channel in the Bajoran wormhole. The pipeline began from a curve known as F1 and ended at the terminus of the wormhole in the Gamma Quadrant.
On the chart "The Tunnel in the Sky", which was seen in the schoolroom aboard Deep Space 9 in 2369, the FTL pipeline was one of the components labeled on a map of the wormhole. (DS9: "In the Hands of the Prophets")