A die having a stationary core or mandrel which is held in place by integral core supports or webs. The porthole die is a modification of the spider die, except that the spider is replaced with a chambered disc that supports the mandrel (sometimes termed a stub mandrel); several portholes running through it annularly about the mandrel, distinguish the porthole types. The die contains a weld chamber so that when the billet is pushed the metal divides to flow around the core supports and welds together in the welding chamber before passing through the die. Porthole dies are used in producing extruded hollow profiles and tubing.