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Fab-Tech Blog

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No Flame + No Smoke = Fluoropolymer Coating On Stainless Steel Duct

Posted by Mike Baranski on Dec 5, 2017 11:19:00 AM
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Fluoropolymer Coating - Q&A

What is a fluoropolymer? A fluoropolymer is a fluorocarbon-based substance that contains atoms of fluorine. It is characterized by a high resistance to solvents, acids, and bases. Fluoropolymers were discovered by happen-stance in 1938 by Dr. Roy J. Plunkett as he was working on freon (for the DuPont corporation) and accidentally polymerized tetrafluoroethylene.

The result was PTFE (polytetrafluoroethylene), more commonly known as Teflon. This material was found to have the lowest coefficient of friction of any known solid and was inert to virtually all chemicals known. Its corrosion resistivity (in almost all applications) exceeds that of glass (borosilicate and enameled glass-steel) and exotic alloys such as Hastelloy, Niobium, Tantalum and Titanium.

Fluoropolymer coated stainless steel vent pipe.jpgWhy was fluoropolymer coating applied to stainless steel duct?

Fluoropolymer coated stainless steel was born out of necessity in the early 1990's as semiconductor companies and their insurance underwriters were not seeing eye to eye on corrosive fume exhaust systems. Existing vent duct products were just not delivering the standard of performance that semiconductor cleanroom applications required and the safety that insurance companies demanded.

Corroded and failing FRP duct.pngInsurance companies were pushing for fire-approved FRP duct, despite its poor chemical resistance, because they would rather have that than have the fab burn down. Semiconductor companies understood the need to eliminate combustible materials from the fab, but they were still seeking greater chemical resistance.

PVC offered somewhat better resistivity, but after several years the material would become embrittled. Insurance companies did not approve of PVC because of the burn characteristics and smoke generation.

In need of a solution, one IBM semiconductor chip plant in Essex Junction, Vermont, set out to find a replacement that would be chemically resistant and make their insurance company happy.

They fully understood that damage due to fire is one issue, but the additional cost for smoke damage is five times greater in a cleanroom setting. In that regard, both PVC and FRP were not acceptable given their various trade-offs between flame spread, smoke generation, and chemical resistance.
 
Fortunately for the semiconductor industry, Fab-Tech rose to the challenge and developed PSP® fluoropolymer coated stainless steel. The combined characteristics of stainless steel and fluoropolymer coating translated to a 0 (zero) flame spread and smoke generation index of less than 20 as certified in ASTM E-84 tests. Furthermore, its chemical resistivity was (and is) far superior to any other material on the market.
 
Needless to say, the first shipments of PSP® coated stainless steel duct were eagerly placed into service at IBM; successfully replacing their failing FRP and PVC duct systems.
 
How is fluoropolymer coating applied to stainless steel duct?
 
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Fab-Tech's PSP® fluoropolymer barrier coating is applied to 300 series stainless steel duct then heated and "baked" to form a chemical and mechanical bond with the metal substrate. 

Through a proprietary primer technology, the remarkably stable bond that is formed between the steel and this non-adhesive polymer is a capability that no other company has been able to replicate successfully. 

Why use fluoropolymer coated stainless steel?

When compared to fiberglass reinforced plastic (FRP), polypropylene (PP) and polyvinylchloride (PVC), the superiority of fluoropolymer coated stainless steel becomes readily apparent.

Based on published data, fluoropolymer coated stainless steel far surpasses other materials in chemical resistance and mechanical stability. 

Fluoropolymer coated stainless steel has been tested in over 400 chemical applications, and proven superior to both FRP duct and plastics when tested for corrosion resistance, chemical concentration tolerance and upper temperature limit.

If you would like more information about PSP® corrosive fume vent pipe and duct, please feel free to download our general information guide below:

Corrosive Fume and Odor Control Exhaust Duct Information Guide

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Topics: coated stainless steel, fluoropolymer coating