Pipelines 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 connectors made of metal, in particular steel, in particular for oil pipelines or natural gas pipelines; pipe sockets made of metal, especially steel; threaded metal pipes, in particular steel; manifolds of metal for pipelines; metal pipe strings for th...