(88f) Fire Protection for Extremely Corrosive Industrial Duct Environments

Many industrial facilities generate extremely corrosive exhaust fumes including high concentration of sulfuric, hydrochloric, nitric and hydrofluoric acids, smoke and high velocity solid particles1,2,3. Various ductwork systems are designed to remove or filter these hazardous wastes. These systems can be found in industries such as industrial metallurgical smelters, steel mills pickling lines, power generation plants, semiconductor fabrication facilities, pulp and paper plants, and chemical processing facilities1. Since these exhaust fumes are corrosive, only plastics such as polypropylene, chlorinated polyvinyl chloride (CPVC) and fiberglass reinforced plastic (FRP), along with certain corrosion resistant alloys can withstand these environments. Up to now, no sprinkler system has been successfully designed to survive in these corrosive environments and protect against fires that originate inside these duct systems1. Loss of a ductwork system due to fire will usually result in total shutdown of the plant for an extended period which can incur substantial financial losses for the operation.

Research has been undertaken to evaluate corrosion resistant properties of candidate materials and coatings in order to develop corrosion resistant sprinklers and fire protection system to protect these flammable FRP duct and exhaust systems. A methodology using crevice corrosion coupon exposure and electrochemical corrosion evaluation techniques4,5 including cyclic polarization and electrochemical impedance spectroscopy has been applied and will be discussed. Typical results from more than 100 coupons tested in the laboratory will be presented in this paper. Based on laboratory testing results, the methodology also included coupon test racks which were assembled and installed in-situ in several industrial exhaust systems for field exposure; typical results will also be presented in the paper. The importance of inert coatings on metal substrate to reduce metal corrosion and to develop prototype sprinklers also will be discussed.

REFERENCES

1. FM Global Operating Standard, 7-78, ?Industrial Exhaust System?, September 2000, 1-14.

2. W. G Pitt and T. N. Andersen, ?Corrosion of Alloys in Simulated Smelter FGD Scrubber Solutions?, Materials Performance (1982), No. 5, 26-29.

3. D. C. Agarwal, ?Alloy Selection Methodology and Experiences of the FGD Industry in Solving Complex Corrosion Problems: The Last 25 Years?, Corrosion 96 (1996), NACE P 00447.

4. D. S. Dunn, G. A. Cragnolina and N. Sridhar, ?An Electrochemical Approach to Predicting Long-Term Localized Corrosion of Corrosion-Resistant High-Level Waste Container Materials?, Corrosion 56 (2000), 90-104.

5. P. C. Su and O. F. Devereux, ?Alternating and Direct Current Electrochemical Studies of a Wool Wax-Based Corrosion Preventive Coating on Aluminum Alloy 2024?, Corrosion 54 (1998), 419-427.