Abstract: A process for producing exhaust gas manifolds is provided, which have a flange for fastening to the cylinder head of an internal combustion engine, manifold pipes for leading off the exhaust gases flowing from the cylinders, and a pipe connector, wherein the pipe connector has openings for the manifold pipes. In accordance with the invention, the pipe connector is designed with reinforced openings. Then the ends of the manifold pipes are introduced into the openings and expanded. In this process, the pipe ends undergo plastic deformation, and the pipes are connected gas-tight.

Abstract: A housing for a flue gas unit is provided that includes a closed jacket and two end walls as well as an insert with inlet pipe an outlet pipe and retaining walls, wherein one of the pipes exits from the housing jacket radially. The housing jacket is cut out around the one pipe, the cutout is closed by a concave closing panel adapted to the shape of the cutout, and the closing panel has an opening for the radial pipe end.

Abstract: A housing for a flue gas unit is provided that includes a closed jacket and two end walls as well as an insert with inlet pipe an outlet pipe and retaining walls, wherein one of the pipes exits from the housing jacket radially. The housing jacket is cut out around the one pipe, the cutout is closed by a concave closing panel adapted to the shape of the cutout, and the closing panel has an opening for the radial pipe end.

Abstract: A process for producing exhaust gas manifolds is provided, which have a flange for fastening to the cylinder head of an internal combustion engine, manifold pipes for leading off the exhaust gases flowing from the cylinders, and a pipe connector, wherein the pipe connector has openings for the manifold pipes. In accordance with the invention, the pipe connector is designed with reinforced openings. Then the ends of the manifold pipes are introduced into the openings and expanded. In this process, the pipe ends undergo plastic deformation, and the pipes are connected gas-tight.

Abstract: An exhaust system of a motor vehicle with an internal combustion engine made of titanium or titanium alloys. In order to prevent undesirable discoloration or corrosion of the titanium surface, the surface is coated with an oxygen-tight inorganic nanocoating.