Sulfide stress cracking mechanism design

Dunlop, thus, concluded that the eac mechanism was a form of scc, i. Sulfide stress cracking nace mr01752002, mr0175iso 15156. Scc stress corrosion cracking evaluates the susceptibility of the pipe to suffer a leakage due to stress corrosion cracking. Sulphide stress cracking of welded joints in weldable martensitic stainless steels. This term should not be confused with stress corrosion cracking scs, since this is anodic in nature.

Sulphide stress cracking of joints in martensitic steels twi. Sulfide stress cracking mostly occurs in very highly acidic environments. For carbon steel, the damage mechanisms ssc sulfide stress cracking and hic hydrogen induced cracking are considered. Sulfide stress cracking ssc is a type of hydrogen cracking which presents a cathodic embrittlement mechanism. Sulfide stress cracking an overview sciencedirect topics. Mechanisms that have been proposed to explain embrittlement include the formation of brittle hydrides, the creation of voids that can lead to bubbles and pressure buildup within a material and e. Sulfide stress corrosion cracking and hydrogen induced cracking of a216wcc wellhead flow control valve body article pdf available in case studies in engineering failure analysis. It is a complex process that is not completely understood because of the variety and complexity of mechanisms that can lead to embrittlement. Pdf sulfide stress corrosion cracking and hydrogen. Featured article criticality assessment of piping systems. It is a progressive type of failure that produces cracking at stress levels that are well below the materials tensile strength. Generally, when designing against stress corrosion cracking, e. Sulfide stress cracking is a function of hydrogen sulfide concentration as low as ppm, hydrogen sulfide partial pressure, stresses, material yield strength, temperature and ph.

Basics of sulfide stress cracking ssc and stress corrosion cracking scc ssc and scc are cracking processes that develop in the presence of water, corrosion and surface tensile stress. Sulfide stress corrosion cracking and hydrogen induced cracking of a216wcc wellhead flow control valve body. The wellhead flow control valve bodies which are the focal point of this failure case study were installed in some of the upstream facilities of khangirans sour gas wells. Ssc is a form of spontaneous brittle breakdown in occurring in highstrength. The mechanism of sulfide stress cracking involves a combination of stress corrosion cracking and hydrogen embrittlement. Sulfide stress cracking ssc is a form of hydrogen embrittlement which is a cathodic cracking mechanism.

Susceptible alloys, especially steels, react with hydrogen sulfide, forming metal sulfides and atomic hydrogen as corrosion byproducts. The simultaneous presence of corrosive environments, high differential pressure, axial loads and temperature, strongly affect the behavior of materials and catastrophic failure mechanisms such as sulfide stress cracking ssc and hydrogen induce cracking hic can be active. As seen in figure 1, cracking was observed only on the tension side of ubend samples. The clscc chloride stress corrosion cracking damage mecha. Corrosionpedia what is sulfide stress cracking ssc. Dunlop named this type of eac sulfide corrosion stress cracking scsc, which is now an obsolete term.