Claims
- 1. A weather resistant stainless steel strip comprising a strip of stainless steel having a thickness up to 0.2 inch and a coating of tin up to 0.05 inch thick, said coating applied to said strip by the process of continuously moving said strip through:
- (a) an oxide removal procedure for removing oxides from said strip surface to provide very low level oxides on said strip surface, said oxide removal procedure includes aggressively pickling said strip surface with a solution of 5-25% hydrochloric acid and 1-15% nitric acid at a temperature of between 80.degree.-140.degree. C. for at least 10 seconds, then chemically activating said strip surface and maintaining a low-oxygen environment about said strip surface during said oxide removal, said aggressively pickling includes subjecting said stainless steel strip to a bath of pickling solution containing hydrochloric acid and nitric acid to said strip surface, said chemical activating includes subjecting said strip to a bath of deoxidizing solution containing zinc chloride; and
- (b) a bath of molten tin having a temperature of at least 449.degree. F. and a lead content of less than 0.02 weight percent lead.
- 2. A stainless steel strip as defined in claim 1, wherein said tin coating thickness is at least 0.0003 inch.
- 3. A stainless steel strip as defined in claim 2, wherein said tin coating thickness is 0.001 to 0.002 inch.
- 4. A stainless steel strip as defined in claim 1, wherein said strip having a speed of 50-115 ft/min.
- 5. A stainless steel strip as defined in claim 1, wherein said strip surface is subjected to aggressively pickling for less than one minute.
- 6. A stainless steel strip as defined in claims 1, wherein said deoxidizing solution includes hydrochloric acid.
- 7. A weather resistant stainless steel strip comprising a strip of stainless steel having a thickness up to 0.2 inch and a coating of tin up to 0.05 inch thick, said coating applied to said strip by the process of continuously moving said strip through:
- (a) an oxide removal procedure for removing oxides from said strip surface, said oxide removal procedure includes aggressively pickling said strip surface then chemically activating said strip surface and maintaining a low-oxygen environment about said strip surface during said oxide removal, said aggressively pickling includes subjecting said stainless steel strip to a bath of pickling solution containing hydrochloric acid and nitric acid to said strip surface, said chemical activating includes subjecting said strip to a bath of deoxidizing solution containing zinc chloride;
- (b) a bath of molten tin having a temperature of at least 449.degree. F. and a lead content of less than 0.02 weight percent lead; and
- (c) said tin coating is coated with an asphalt based paint.
INCORPORATION BY REFERENCE
This application is a Continuation of U.S. patent application Ser. No. 08/000,101, filed Jan. 4, 1993, now abandoned, and which is a Continuation-In-Part Application of U.S. patent application, Ser. No. 858,662, filed Mar. 27, 1992, entitled Hot Dip Terne Coated Roofing Material, now U.S. Pat. No. 5,314,758.
The present invention relates to the art of coating a metal strip material and more particularly to the process of coating a strip of stainless steel roofing material with a hot-dipped coating of tin.
U.S. Pat. Nos. 4,987,716 and 4,934,120 illustrate metal roofing systems of the type to which this invention relates and are incorporated herein by reference. U.S. patent application Ser. No. 858,662 filed Mar. 27, 1992, illustrating a low lead coating is also incorporated herein by reference.
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Continuations (1)
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101 |
Jan 1993 |
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Continuation in Parts (1)
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858662 |
Mar 1992 |
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