04077434 is referenced by 66 patents and cites 10 patents.

A sealed lay-in electrical conduit duct which is oil-tight and is comprised of U-shaped sealing collars which telescope into adjacent ends of aligned open ended sheet metal duct sections which are troughs generally U-shaped in cross-section and have their open sides unobstructed throughout their length and closable by a movable sealing trough cover. The sealing collars and duct sections have telescoping bottom and side wall portions, each of which carries elongated cooperating interengaging rib and groove elements which are aligned and extend normally to the longitudinal axis of the duct sections. Each collar member carries a sealing element extending throughout substantially its entire length which covers and seals the line of juncture of the adjacent ends of trough sections held in rigid aligned relation by the collar member. A closure member carrying sealing elements covers the open area between the ends of the side walls of each collar member and cooperates with the sealing trough covers to complete the seal of the duct in the areas adjacent the joined ends of the duct sections.

Title
Sealed lay-in conduit duct
Application Number
5/690512
Publication Number
4077434
Application Date
May 27, 1976
Publication Date
March 7, 1978
Inventor
John R Breckenridge
Anoka
MN, US
Robert D Frayseth
Minneapolis
MN, US
Edgar W Sieckert
Princeton
MN, US
Agent
Schroeder Siegfried Ryan Vidas & Steffey
Assignee
Federal Cartridge Corporation
MN, US
IPC
F16L 9/22
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