Stoneware corrosion resistance

Since the formation of the chlorohydrin is accompanied by the production of an equimolar quantity of hydrogen chloride [7647-01 -OJ, the reaction solution is strongly acidic and corrosive. The first chlorohydrin reaction towers were built of stoneware or of mild steel and lined with mbber and ceramic tiles. More recently corrosion-resistant reinforced plastics have been used with good results, but operating pressures must be maintained at or near atmospheric. 

Red and blue acid-resistant bricks are resistant to all inorganic and organic chemicals, except for hydrofluoric acid and hot concentrated caustic alkalis. Acid-resistant fireclay bricks are used for conditions involving elevating temperatures and corrosive condensates. Highly vitrified materials such as chemical stoneware, porcelain and basalts are used for extremely severe duties or where contamination of the process liquors is undesirable. 

Owing to their almost complete resistance to corrosion, stoneware and porcelain occupy a unique position as materials in the chemical industry. Stoneware bodies can be compounded from many different raw materials to give the properties required and to permit the manufacture of articles up to a considerable size. Porcelain, on the other hand, is not generally used for very large articles, but owing to its completely vitreous nature it normally shows a much greater resistance to corrosion than does stoneware. 

Stoneware is used mainly for storage, transportation and processing, where its great resistance to corrosion is important. As it can be glazed and is completely non-reactive, it is also used in situations where cleanliness is important, as in the food industry. 

In aqueous media where hydrochloric and hypochlorous acid and halogens are present in either vapor or liquid phase, the utility of the above materials of construction is severely lin ited and can best be determined by rates of corrosion study during pilot laboratory operation. Tantalum, zirconium, and titanium are usually resistant but expensive. The plastics are of variable resistance and are severely limited by temperature and solvent attack. Stoneware, Karbate, glass, glazed tile, carbon brick, and enameled steel all have utility within rigid limits. The other metals and alloys are usually questionable but may be desirable for replaceable piarts i... 

Laboratory sinks, incorporated in the work tops, are usually made of stainless steel or epoxy resin to provide the needed resistance to corrosives, solvents, and other organic and inoigatuc materials. Older sinks are often stoneware. However, current restrictions on disposing of chemicals into the sanitary system should reduce the burden on the laboratory sink and the remaining plumbing components. 

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