Corrosion weak-sulfuric-acid

The bottoms from the stripper (40—60 wt % acid) are sent to an acid reconcentration unit for upgrading to the proper acid strength and recycling to the reactor. Because of the associated high energy requirements, reconcentration of the diluted sulfuric acid is a cosdy operation. However, a propylene gas stripping process, which utilizes only a small amount of added water for hydrolysis, has been described (63). In this modification, the equiUbrium quantity of isopropyl alcohol is stripped so that acid is recycled without reconcentration. Kquilibrium is attained rapidly at 50°C and isopropyl alcohol is removed from the hydrolysis mixture. Similarly, the weak sulfuric acid process minimizes the reconcentration of the acid and its associated corrosion and pollution problems. 

Strong sulfuric acid above 85 percent strength is entirely noncorrosive. As the sulfuric acid is diluted with water, it becomes exponentially more corrosive to carbon steel. Small amounts of weak sulfuric acid were carrying over into the reactor effluent line from the caustic settler. 

Boric oxide is an excellent Lewis acid. It coordinates even weak bases to form four-coordinate borate species. Reaction with sulfuric acid produces H[B(HSO 4] (18). At high (>1000° C) temperatures molten boric oxide dissolves most metal oxides and is thus very corrosive to metals in the presence of oxygen. 

Although hydrogen cyanide is a weak acid and is normally not corrosive, it has a corrosive effect under two special conditions (/) water solutions of hydrogen cyanide cause transcrystalline stress cracking of carbon steels under stress even at room temperature and in dilute solution and (2) water solutions of hydrogen cyanide containing sulfuric acid as a stabilizer severely corrode steel (qv) above 40°C and stainless steels above 80°C. 

Sulfur dioxide is extremely stable to heat, even up to 3600°F. It docs not form flammable or cxplosi c mixtures witli air. It will, howe cr, react with water or steam to produce toxic and corrosive fumes.When the gas dissolves in water it forms a weak acid solution of sulfurous acid (H S03), which is corrosi C [Pg.274]

Sulfuric acid (H SO ), also known at battery acid, is the leading chemical manufactured in the United States, with an annual production of 40 million tons per year. Most of it is used in the manufacture of fertilizers, explosives, pigments, and dyes. It has the nasty attribute of being able to extract hydrogen and oxygen from organic substances, which can cause serious burns. It is strongly corrosive and, in both concentrated and weak solutions with water, will react with most metals. 

One final consideration when storing solid sulfur is the almost inevitable presence of sulfuric acid. Sulfur can become naturally contaminated with sulfuric acid through the presence of thiobacilli thiooxidans3 or continuous exposure to direct sunlight.4 Recent research has demonstrated the short-term effectiveness of certain bactericides in delaying bacterial colonization. Nevertheless, discrete pockets of weak (highly corrosive) sulfuric acid should always be presumed to exist within a sulfur storage pile. Hydrochloric acid, which may also be present when solid sulfur has been transported by vessel,5 must be neutralized to avoid potentially disastrous corrosion of downstream equipment. 

ALUM (10043-01-3) Al2(SOj3 Noncombustible solid. Forms sulfuric acid with water. Aqueous solution has a violent reaction with bases, amines, amides, inorganic hydroxides, and many other materials. See also sulfuric acid. Dry material is weakly corrosive to carbon steel aqueous solution attacks aluminum and other metals, forming hydrogen gas. Hydrogen gas can accumulate to explosive concentrations within enclosed or confined spaces. 

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