Hydrogen sulfide corrosion

The initial laboratory investigation of the process now being piloted at the ASARCO El Paso plant involved bench scale evaluations of 19 different primary sulfur dioxide reduction catalysts. Also, fixed-bed and fluid-bed catalysis were compared, and various construction materials were evaluated in the corrosive hydrogen sulfide and sulfur vapor atmosphere generated in gas phase reduction of sulfur dioxide. 

SRB, known as Desulfovibrio desulfuricans in the scientific community, are bacteria that are nonpathogenic (i.e., they are not capable of causing disease) and they are anaerobic bacteria (i.e they require an oxygen-free aqueous environment). However, they are capable of causing severe corrosion of iron material in a water system because they produce enzymes that have the power to accelerate the reduction of sulfate compounds to the corrosive hydrogen sulfide. Thus, SRB act as a catalyst in the reduction reaction (Yuzwa 1991). However, in order for this reduction to occur, four components must be present. That is, SRB must be present, sulfates must be present, an external energy source in the form of free electrons must be present, and the temperature of the water must be less than approximately 66°C (150°F). 

Carbon dioxide (COj) corrosion Hydrogen sulfide (HjS) corrosion Preferential weld corrosion Erosion and erosion-corrosion Crevice corrosion Flange face corrosion Cavitation Dead-leg corrosion Under-deposit corrosion Microbial corrosion Oxygen corrosion Galvanic corrosion External corrosion Corrosion under insulation (CUI)... 

Gasoil, kerosene, fuel oil and crude oil ASTs the floors and the roofs suffer severely from corrosion. Hydrogen sulfide is the main cause of the severe corrosion of the roofs. 

Finally, there are some limits regarding LPG fuels butadiene content (0.5 wt. % maximum, ISO 7941), the absence of hydrogen sulfide (ISO 8819) and copper strip corrosion (class 1, ISO 6251) which are not usually problems for the refiner. 

Corrosion protection is indispensable, especially concerning certain vulnerable parts of the aircraft such as the combustion chamber and turbine. The potential hazards are linked to the presence of sulfur in various forms mercaptans, hydrogen sulfide, free sulfur, and sulfides. 

Hydrogen chloride released dissolves in water during condensation in the crude oil distillation column overhead or in the condenser, which cause corrosion of materials at these locations. The action of hydrochloric acid is favored and accelerated by the presence of hydrogen sulfide which results in the decomposition of sulfur-containing hydrocarbons this forces the refiner to inject a basic material like ammonia at the point where water condenses in the atmospheric distillation column. 

Sweetening. Another significant purification appHcation area for adsorption is sweetening. Hydrogen sulfide, mercaptans, organic sulfides and disulfides, and COS need to be removed to prevent corrosion and catalyst poisoning. They ate to be found in H2, natural gas, deethanizer overhead, and biogas. Often adsorption is attractive because it dries the stream as it sweetens. 

Another ak pollutant that can have very serious effects is hydrogen sulfide, which is largely responsible for the tarnishing of silver, but also has played a destmctive role in the discoloration of the natural patinas on ancient bronzes through the formation of copper sulfide. Moreover, a special vulnerabihty is created when two metals are in contact. The electromotive force can result in an accelerated corrosion, eg, in bronzes having kon mounting pins. 

Nickel sulfide, NiS, can be prepared by the fusion of nickel powder with molten sulfur or by precipitation usiag hydrogen sulfide treatment of a buffered solution of a nickel(II) salt. The behavior of nickel sulfides ia the pure state and ia mixtures with other sulfides is of iaterest ia the recovery of nickel from ores, ia the high temperature sulfide corrosion of nickel alloys, and ia the behavior of nickel-containing catalysts. 

Alkali Treatment. Caustic washing is the treatment of materials, usually products from petroleum refining, with solutions of caustic soda. The process consists of mixing a water solution of lye (sodium hydroxide or caustic soda) with a petroleum fraction. The treatment is carried out as soon as possible after the petroleum fraction is distilled, since contact with air forms free sulfur, which is corrosive and difficult to remove. The lye reacts either with any hydrogen sulfide present to form sodium sulfide, which is soluble in water, or with mercaptans, foUowed by oxidation, to form the less nocuous disulfides. 

Various patents (22—24) have been issued claiming the use of tetrakis(hydroxymethyl)phosphonium sulfate in, for example, water treating, pharmaceuticals (qv), and in the oil industry where this compound shows exceptional activity toward the sulfate-reducing bacteria that are a primary cause of hydrogen sulfide formation and consequent problems associated with souring and corrosion (25). 

Corrosivity. Anhydrous hydrogen sulfide has a low general corrosivity toward carbon steel, aluminum. Inconel, Stehite, and 300-series stainless steels at moderate temperatures. Temperatures greater than ca 260°C can produce severe sulfidation of carbon steel. Alternative candidates for hydrogen... 

Spent Acid or Burning. Burners for spent acid or hydrogen sulfide are generally similar to those used for elemental sulfur. There are, however, a few critical differences. Special types of nozzles are required both for H2S, a gaseous fuel, and for the corrosive and viscous spent acids. In a few cases, spent acids maybe so viscous that only a spinning cup can satisfactorily atomize them. Because combustion of H2S is highly exothermic, carehil design is necessary to avoid excessive temperatures. 

Many of the by-products of microbial metaboHsm, including organic acids and hydrogen sulfide, are corrosive. These materials can concentrate in the biofilm, causing accelerated metal attack. Corrosion tends to be self-limiting due to the buildup of corrosion reaction products. However, microbes can absorb some of these materials in their metaboHsm, thereby removing them from the anodic or cathodic site. The removal of reaction products, termed depolari tion stimulates further corrosion. Figure 10 shows a typical result of microbial corrosion. The surface exhibits scattered areas of localized corrosion, unrelated to flow pattern. The corrosion appears to spread in a somewhat circular pattern from the site of initial colonization. 

Both iron and aluminum are particulady troublesome because of their abiUty to act as coagulants. Also, their soluble and insoluble hydroxide forms can each cause precipitation of some water treatment chemicals, such as orthophosphate. Airborne contaminants usually consist of clay and dirt particles but can include gases such as hydrogen sulfide, which forms insoluble precipitates with many metal ions. Process leaks introduce a variety of contaminants that accelerate deposition and corrosion. 

Materials The damage that air pollutants can do to some materials is well known ozone in photochemical smog cracks rubber, weakens fabrics, and fades dyes hydrogen sulfide tarnishes silver smoke dirties laundry acid aerosols ruin nylon hose. Among the most important effects are discoloration, corrosion, the soiling of goods, and impairment of visibility. 

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