Pipelines comprised of tubes, pipes, valves, ducts  and junctions made of metal, especially steel; penstock pipes of steel for the transport of crude oil or natural gas; pipe fittings made of metal, in particular of steel, in particular for oil pipelines or natural gas pipelines; gas-tight threaded pipe connectors made of metal, in particular steel, in particular for oil pipelines or natural gas pipelines; pipe sockets being metal pipe fittings made of metal, especially steel; threaded meta...