Claims
- 1. In a coating line for coating a ferrous base metal strip with a molten coating metal, said coating line being of the type having a strip preparation furnace comprising a direct fired furnace with an exhaust system for products of combustion comprising a duct leading from said direct fired furnace to an exhaust fan, a controlled atmosphere heating furnace, at least one cooling chamber and a snout extending beneath the surface of a bath of said molten coating metal, all connected serially in sealed relationship, the improvement comprising an air dilution opening in said duct in the form of a gap in said duct to cool and dilute said products of combustion ahead of said fan, heat resistant door means shiftable between an open position out of said gap and a closed position within said gap to seal said direct fired furnace from said exhaust fan and said air dilution opening, means to shift said door means from said open position to said closed position at the time of a line stop, said door means being thinner than said gap so that said exhaust fan draws ambient air through the upper portion of said gap and over said door means when said door means is in said closed position to cool said door means, and means at the time of a line stop to introduce a non-oxidizing atmosphere at a positive pressure into said strip preparation furnace to purge said strip preparation furnace and to prevent oxygen from the ambient atmosphere from entering said strip preparation furnace.
- 2. The structure claimed in claim 1 wherein said means to introduce said non-oxidizing atmosphere at a positive pressure comprises a purge valve located in said strip preparation furnace.
- 3. The structure claimed in claim 2 wherein said non-oxidizing atmosphere is nitrogen.
- 4. The structure claimed in claim 1 wherein said door means comprises a slab-like, refractory lined door.
- 5. The structure claimed in claim 13 wherein said means to introduce said non-oxidizing atmosphere at a positive pressure comprises a purge valve located in said strip preparation furnace.
CROSS REFERENCE TO RELATED APPLICATION
This is a division of application Ser. No. 768,033, filed Feb. 14, 1977, U.S. Pat. No. 4148946 in the name of the same inventors and entitled METHOD AND MEANS FOR MAINTAINING A NON-OXIDIZING ATMOSPHERE AT POSITIVE PRESSURE WITHIN THE METALLIC STRIP PREPARATION FURNACE OF A METALLIC COATING LINE DURING LINE STOPS--.
US Referenced Citations (5)
Divisions (1)
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Number |
Date |
Country |
Parent |
768033 |
Feb 1977 |
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