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United States Patent | 3,557,838 |
Savage | January 26, 1971 |
A duct stiffener device for blind insertion into sheet metal ducts which consists of a rod affixed to a sheet metal type screw.
Inventors: | Savage; Arthur P. (Woodbine, MD) |
Appl. No.: | 04/800,171 |
Filed: | February 18, 1969 |
Current U.S. Class: | 138/108 |
Current International Class: | F16L 55/00 (20060101); F16L 9/04 (20060101); F16L 9/00 (20060101); F16l 055/00 () |
Field of Search: | 138/108,(A.C.Dig.) 85/41 |
1523268 | January 1925 | McColl |
1629189 | May 1927 | Weaver et al. |
2289785 | July 1942 | Hutchison |