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NIC Granted Electrofusion Welding Patent

Wed, 25 October, 2023

The Non-Metallic Innovation Centre (NIC) has been granted a United States patent for an electrofusion welding technique for reinforced thermosetting resin (RTR) pipe joints.

The patent, ‘Apparatus and Method for Electrofusion Welding of Reinforced Thermosetting Resin Pipe Joints’ (US-11761571-B2), covers a system for joining two RTR pipes with tapered spigot ends using a specially-designed coupler, with two tapered sockets ends, to receive the two pipes.

The coupler includes a resistive element and electrodes that extend to the coupler’s exterior. Once the pipes are inserted into the coupler, a thermoplastic material is deposited between exterior of the pipes and the inside of the coupler before electricity is applied to the electrodes, which melts the thermoplastic material that, once cooled, joins the two pipes to the coupler.

This patented technique can replace the use of adhesive or threaded joints for RTR pipe, which can fail due to improper installation. This patented technique can also improve sealing and reliability.

This is the second United States patent granted to the NIC for joining RTR pipes, with the first using a rotational friction welding technique.

RTR pipes offer an economical alternative to traditional carbon steel pipes, gaining them acceptance as a solution for oil and gas service.

This latest patent shows how the NIC is helping to increase confidence in the use of non-metallic materials and technologies through research and the addressing of challenges for industry.