Abstract: A process for producing a hollow body provided with a transverse branch, in a forming tool from a tubular metal section, which process uses an internal high pressure forming technique. The process provides for the crown of the branch to be punched out by a platen (which supports the branch during its formation), at an internal pressure which is higher than the maximum production internal pressure (Pilmax). The end face of the platen at its head end is for this purpose of a larger dimension than the active supporting face and has a cutting edge which peripherally surrounds the active supporting face, in the manner of a collar.