Resistance to hydrogen sulfide

Both austenitic and super SS s have excellent resistance to erosion-corrosion in velocities up to 85 ft/s (26 m/s). Usually, copper base alloys are not considered because of poor resistance to hydrogen sulfide/10 poor resistance to erosion, and low strength. Prevention of corrosion by coatings is usually impractical in production equipment because of limited life, as described previously, and because the coating can be blown off by sudden depressurization when the operating pressure is above -650 psi (4,480 kPa). 

The austenitic alloys are resistant to hydrogen sulfide, chlorides, and moisture. There are also advantages to using stainless steel in combination with other metals. This is tme where the more anodic material has a mnch larger surface area than the cathodic material. For example, galvanic corrosion has not been a problem where stainless steel fasteners are used to hold down aluminum deck plates. This is because the amount of stainless steel (cathodic material) used to hold down the aluminum (anodic material) is quite small when comparisons of surface area ratios are made. Overall, stainless steel has been demonstrated to provide excellent corrosion resistance in severe atmospheric environments. 

Titanium dioxide is extremely stable at high temperatures (melting point 1800 °C). Titanium oxide pigments are chemically very stable. They are insoluble in all liquids with the exception of concentrated sulfuric acid and hydrofluoric acid (and only at 1000 °C). They are also resistant to hydrogen sulfide and other gases generally found in industrial atmospheres. 

Type 5 FKM These elastomers are produced from five different feedstocks. These include VDF (vinylidene fluoride), HFP (hexafluoropropylene), TFE (tetrafluoroethyl-ene), PMVE (perfluoromethylvinylether), and ethylene. These polymers are known for their high-temperature resistance to hydrogen sulfide. 

In a reducing atmosphere, molybdenum is resistant at elevated temperatures to hydrogen sulfide, which forms a thin adherent sulfide coating. In an... 

An MRL of 0.07 ppm has been derived for acute-duration inhalation exposure to hydrogen sulfide. This MRL is based on a LOAEL of 2 ppm for respiratory effects—bronchial obstruction (30% change in airway resistance) in 2/10 persons with asthma reported in the Jappinen et al. 1990 study (Table 2-1 LSE 16). An uncertainty factor of 30 was applied,... 

Unless heavily cold worked, the austenitic stainless steels are resistant to hydrogen stress cracking such as that caused by hydrogen sulfide. They are also resistant to hydrogen embrittlement caused by phenomena other than cathodic charging. If sensitized, austenitic stainless steels can also be susceptible to intergranular corrosion. 

The Pd-Au and Pd-Cu alloys retained their metallic luster upon exposure to hydrogen sulfide and recovered their activity after removal of H2S [74], implying that both alloys were resistant to formation of bulk sulfides. The unalloyed Pd and Pd-Ag membranes were much changed in appearance, according to McKinley, indicative of the formation of bulk sulfides. X-ray diffraction analysis at Eltron Research Inc. shows that unalloyed Pd forms the bulk sulfide, Pd4S, and that Pd-Ag alloys form bulk palladium-silver sulfides, leading to failure of membranes exposed to under 20 ppmv H2S in the range 593-713 K (320-440 °C) [75]. The Pd 60-Cu 40 (wt%) alloys resist formation of bulk sulfides, but were not completely satisfactory for use with H2S [75], in accord with the work of McKinley [74]. 

Figure 8. Resistance changes of polyaniline nanofiber films containing ZnCl2 ( — CdCU (—), and CuCh (—) on exposure to hydrogen sulfide (10 ppm).

Despite the fact that sulfur metal compounds poison many metallic catalysts, transition-metal compounds such as molybdenum and tungsten, while converting to sulfides during use, retain their ability to hydrogenate aromatic compounds (6) because their exceptional resistance to poisons. Sulfide catalysts are also very resistant to carbon deposition, which is illustrated by their use for converting residual oils. Arsenic, as well as nickel and vanadium contained in heavy petroleum fractions, are some of the few substances that cause significant deactivation. This activity decrease is due to physical blockage of pore structure in supported catalysts. 

TABLE 4—Resistance to gaseous sulfidation. Environment argon-5 % hydrogen-5 % carbon monoxide-1 % carbon dioxide-0.15 % hydrogen sulfide. 

BRUSH ALLOY 25, a heat-treatable beryllium copper product contains 1.80 to 2.00% beryllium. BRUSH ALLOY 25 is resistant to hydrogen embrittlement, and not susceptible to either sulfide stress cracking or chloride stress cracking. Moreover, in marine and certain industrial environments this alloy outperforms stainless steel, titanium, and most copper based alloys. Beryllium copper is available in a wide range of forms, including strip, tube, rod, bar, extrusions, casting and master alloy, and forging billet. 

Pure silver has a brilliant white metallic luster. It is a little harder than gold and is very ductile and malleable, being exceeded only by gold and perhaps palladium. Pure silver has the highest electrical and thermal conductivity of all metals, and possesses the lowest contact resistance. It is stable in pure air and water, but tarnishes when exposed to ozone, hydrogen sulfide, or air containing sulfur. The alloys of silver are important. 

Titanium whites resist various atmospheric contaminants such as sulfur dioxide, carbon dioxide, and hydrogen sulfide. Under normal conditions they are not readily reduced, oxidi2ed, or attacked by weak inorganic and organic acids. Titanium dioxide dissolves slightly in bases, hydrofluoric acid, and hot sulfuric acid. Owing to its chemical inertness, titanium dioxide is a nontoxic, environmentally preferred white pigment. 

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