Insulated self-threading fitting

Claim 1

An insulated self-threading fitting comprising a metal tubular member having connecting means on one end and tapered internal threads inside the opposite end and a liner-guide sleeve of insulating material secured within said tubular member; said liner-guide sleeve extending substantially beyond the end of said tubular member having the internal threads for insertion into a conduit upon which the fitting is to be self-threaded to ensure coaxial alignment of the fitting with such a conduit, said tubular member being provided with a cylindrical throat portion adjacent the end having the connecting means thereon and said liner guide sleeve being provided with an end portion having a diameter substantially equal to the internal diameter of said throat portion with said end portion of said sleeve being defined by two circumferential retaining flanges spaced apart at a distance equal to the length of said throat portion and having slot means extending axially from the end thereof to permit a reduction in diameter to allow insertion of one of said flanges through said thread portion so that said flanges will lock said sleeve against axial movement relative to said tubular member.