Multiple walled chimney
CA 2004045 C · Owner: Annestedt, James W. Sr. · Inventors: Annestedt, James W. Sr.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A multiple walled metal chimney formed of a plurality of axially joined chimney sections each of which utilizes positionally captured spacer rings. Joint clamps are used to connect the chimney sections for formation of the complete chimney conduit. The spacer rings are positionally captured between annular shoulders formed in the inner and outer walls of the chimney sections to eliminate welding of the rings. The rings may include an expansion joint to allow circumferential expansion and contraction of the ring with the walls.
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 28, 1989 and granted January 16, 1996. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended November 28, 2009.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by November 28, 2011.
- 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.