Abstract: An internal ring coupler for fusing and sealing abutted ends of two pipes is provided. The ring coupler formed by a plastic ring having a substantially flat outer surface with at least two bands of thermoplastic welding rod encircling the outer surface of the plastic ring is provided. The coupling is placed on the inner circumference of two abutted plastic pipe ends. An electrical current is applied to the bands fusing the ring coupler to the interior of the ends of the two pipes to fuse the welding rod between the pipes and the coupler forming a seal over the pipe join.

Abstract: An innovative method of thermoplastic electrofusion welding uses a novel compressible dual resin thermoplastic welding rod. This welding rod comprises an inner core made of a soft first thermoplastic resin, a resistance wire wrapped around the inner core, and an outer coating surrounding the inner core and wire. The outer coating is made of a second thermoplastic resin that is harder than the first thermoplastic resin of the inner core. The first thermoplastic may be made of thermoplastic vulcanizate (TPV). The second thermoplastic resin may be made of a high-density polyethylene (HDPE). Because of its compressibility, this dual resin electrofusion welding rod greatly facilitates the seating of parts that are to be welded together.

Abstract: An improved welding rod having a solid homogeneous core of thermoplastic material and a resistance element comprised of a plurality of wires is presented with a method and apparatus for forming the welding rod. The welding rod is positioned between members of the thermoplastic material to be welded and a current and pressure is applied to the resistance element causing the thermoplastic material of the solid core and the adjacent thermoplastic members to fuse and form a unitary weld. Simultaneously the electrical resistance element is embedded in the weld, mechanically reinforcing and strengthening the connection. There is also disclosed a method for electric fusion welding of thermoplastic members wherein the welding rod is pre-attached to one of the thermoplastic members.

Abstract: An improved welding rod having a solid homogeneous core of thermoplastic material and a resistance element comprised of a plurality of wires is presented with a method and apparatus for forming the welding rod. The welding rod is positioned between members of the thermoplastic material to be welded and a current and pressure is applied to the resistance element causing the thermoplastic material of the solid core and the adjacent thermoplastic members to fuse and form a unitary weld. Simultaneously the electrical resistance element is embedded in the weld, mechanically reinforcing and strengthening the connection. There is also disclosed a method for electric fusion welding of thermoplastic members wherein the welding rod is pre-attached to one of the thermoplastic members.