Method of attaching a self-aligning flange to a vacuum pipe and forming a large diameter extruded pipe

A method of attaching a self-aligning flange to a vacuum pipe includes a flange member, a collar member and a stop member. An inner perimeter of the collar member is sized to receive an outer perimeter of a pipe. The flange member extends outward from an outer perimeter of the collar member. The stop member extends inward from the inner perimeter of the collar member. A method of forming a large diameter extruded pipe includes a continuous cross section of at least six inches in diameter. It is preferable to weld a flange to one end of the large diameter extruded pipe. Immediately after the large diameter extruded pipe has been formed in an extrusion press, it is sprayed with a coolant to increase the surface hardness thereof.