Metal tubing, in particular of steel; penstock pipes of steel for the transportation of petroleum and natural gas; junctions of metal, in particular of steel, for pipes, in particular for oil pipelines and gas pipelines; gastight threaded couplings of metal, in particular of steel, in particular for oil pipelines or gas pipelines; pipe muffs of metal, in particular of steel; threaded pipes of metal, in particular of steel; manifolds of metal for pipelines; pipe strings in the nature of pipes ...