Stress corrosion cracking hydrogen sulfide

Hydrogen embrittlement, 428 Hydrogen production increase (catalyst poisoning), 164-165 Hydrogen sulfide, 90,106,111—112, 116, 133, 144, 173, 421-422 Hydrogen-assisted stress corrosion cracking, 90... 

This phenomenon is generally encountered in high strength steels of Rockwell hardness above 22 in a sour oil field environment. It is a special case of hydrogen stress cracking, also called hydrogen embrittlement. Factors responsible for sulfide stress corrosion cracking (SCC) are ... 

Parts and components that come in contact with wet hydrogen sulfide should be provided with sulfide stress corrosion cracking prevention measures in accordance with the latest edition of NACE MR 01-75. 

Cracking was caused by stress-corrosion cracking (see Chap. 9, Stress-Corrosion Cracking ) involving hydrogen sulfide and/or moist sulfur dioxide. The sulfur entered the cooling water stream through process leaks, which were repaired. 

In water solutions containing hydrogen sulfide, austenitic steels fail by stress corrosion cracking when they are quenched and tempered to high strength and hardness (above about Rockwell C24). 

Aluminum and silicon bronzes are very popular in the process industries because they combine good strength with corrosion resistance. Copper-beryllium alloys offer the greatest strength and excellent corrosion resistance in seawater and are resistant to stress-corrosion cracking in hydrogen sulfide. 

Corrosion by hydrogen sulfide in partial oxidation plants can be controlled by the use of austenitic steels, but special care to ensure proper stress relief of welds is advisable to avoid stress corrosion cracking in these plants caused by traces of chlorine sometimes present in the feed oil. 

Schmitt [52] reviewed the effect of elemental sulfur on corrosion of construction materials (carbon steels, ferric steels, austenitic steels, ferritic-austenitic steels (duplex steels), nickel and cobalt-based alloys and titanium. Wet elemental sulfur in contact with iron is aggressive and can result in the formation of iron sulfides or in stress corrosion cracking. Iron sulfides containing elemental sulfur initiate corrosion only when the elemental sulfur is in direct contact with the sulfide-covered metal. Iron sulfides are highly electron conductive and serve to transport electrons from the metal to the elemental sulfur. The coexistence of hydrogen sulfide and elemental sulfur in aqueous systems, that is, sour gases and oils, causes crevice corrosion rates of... 

Y.Y. Chen, Y.M. Liou, H.C. Shih, Stress corrosion cracking of type 321 stainless steeb in simulated petrochemical process environments containing hydrogen sulfide and chloride. Mater. Sci. Eng. A 407 (2005) 114-126. 

HIC is also referred to as stepwise cracking. The cracks propagate and interconnect hydrogen blisters to form a step pattern. Similar to sulfide stress corrosion, HIC does not involve substantial metal ranoval but can cause failure of the component through internal crack propagation. 

Some specific corrosion environments, in the presence of applied tensile stress on the metal siuface (above some threshold vtilue), can cause stress-corrosion cracking (SCC). The somce of stresses can be extemtil, but residual stresses can tilso cause SCC failures. Specific corrosive pollutants, which may contribute to the SCC of carbon steels, are for example, the carbonates in water. Sulfide stress cracking (SSC) commonly occms on the outside of a pipe where sulfate-reducing bacteria me present at a soil pH of 3-7. Because of the produced iron sulfide (FeS), which adsorbs readily on the steel surface, hydrogen atoms generated... 

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