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.
