Method of joining hollow plastics members by fusion
CA 2045527 C · Owner: Bg Plc · Inventors: Stafford, Trevor George
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
Members such as natural gas distribution pipes (10 12) of polyethylene, or other plastics material are assembled with an internal liner (14) and heat is applied to the pipes externally by an electric heater assembly (18). After cooling the heater assembly is removed. The outer surface of the liner (14) fuses and bonds to the insides of the pipes. The pipe end portions fuse and bond across the interface (30). The liner is for example of polyethylene of molecular weight more than half a million containing finely divided carbon as filler. The liner is extruded and cold drawn to reduce its diameter to a close fit in the pipes. The applied heat causes the liner to expand more than the pipes. …
Read the whole patent
Listed from its CIPO record in Patent Yard's archive of Canadian patents past their term. Its claims, description and drawings are in the CIPO record and on Google Patents, and the Claude kit works from them.
Why it's free to use
- Filed November 21, 1990 and granted October 19, 1999. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended November 21, 2010.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by November 21, 2012.
- We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
Timeline
Timeline From CIPO dates
Sources & verification
Official CIPO records
Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.