The Druzhba pipeline (also has been referred to as the Friendship Pipeline and the Comecon Pipeline) is the world's longest oil pipeline and one of the biggest oil pipeline networks in the world.
It carries oil some 4,000 kilometres (2,500 mi) from the eastern part of European Russia to points in Ukraine, Belarus, Poland, Hungary, Slovakia, the Czech Republic and Germany.
The network also branches out into numerous pipelines to deliver its product throughout Eastern Europe and beyond. The name "Druzhba" means "friendship", alluding to the fact that the pipeline supplied oil to the energy-hungry western regions of the Soviet Union, to its "fraternal socialist allies" in the former Soviet bloc, and to western Europe.
Today, it is the largest principal artery for the transportation of Russian (and Kazakh) oil across Europe.
According to en.wikipedia