Which alloy is best to resist sulfide stress cracking and stress corrosion cracking. Hydrogen sulfide is a gas more commonly associated with the smell of rotten eggs and blocked drains. Partial pressure of the h 2 s is determined by multiplying the mole fraction of h 2 s in the gas by the total pressure. Hydrogen induced cracking and sulphide stress cracking of carbonmanganese steels 517 introduction, sulphide inclusions are considered as the most dangerous sites for hic initiation. Tib and mncrmo was evaluated using constant load tensile test. The steels sscc susceptibility was determined by constant load tensile according to nace tm0177 standard. An industry value that has been developed is nace mr01. Corrosionpedia what is sulfide stress cracking ssc. H 2 s can cause corrosion of stainless steels such as 316 and 410 stainless in the form of sulfide stress cracking. Sulfide stress cracking ssc is just one of several forms of hydrogen. The article also introduces a quantitative criterion to determine the maximum allowable defect size based on fracture mechanics principles. The mechanism of sulfide stress cracking involves a combination of stress. Sulfide stress cracking nace mr01752002, mr0175iso 15156. Pdf sulfide stress corrosion cracking and hydrogen.
Hydrogen sulfide is a colorless, very poisonous, flammable gas with the characteristic foul odor of rotten eggs. In a previous post, we discussed the broad differences between anodic and cathodic forms of environmentally assisted cracking eac. Although the general causes of stressrelief cracking are known, different metals or alloys exhibit different types of stress relief mechanisms, but the general underlying mechanisms still unknown. Sulfide stress cracking, a form of hydrogen embrittlement, first became a serious problem in the oil industry in 1951. The ssc of medium strength steels has been a continuing source of trouble in the oil fields, and from these troubles has evolved in international standards 6. In that article, we concluded that while localized corrosion appears to be a prerequisite for anodic eac modes such as stress corrosion cracking scc, hydrogenassisted eac mechanisms like hydrogen stress cracking hsc are exacerbated at cathodic potentials.
Reliability of dissimilar metal welds subjected to sulfide. The mechanism of sulfide stress cracking involves a combination of stress corrosion cracking and hydrogen embrittlement. The general reasons for stressrelief cracking are known, but the underlying mechanisms are still a source of debate. Hydrogen induced cracking and sulphide stress cracking of. Sulfide stress cracking ssc vs hydrogen induced cracking. Processes or conditions involving wet hydrogen sulfide, i. The use of dss has been restricted in some cases because of stress corrosion cracking scc, which can initiate and grow in either the ferrite or austenite phase depending on the environment. Used sem observed the fracture, and then the steels corrosion rate and shortterm corrosion behavior were analyzed by electrochemical polarization. Is sulfide stress cracking an anodic or a cathodic process. Sulfide stress cracking of nickelcontaining lowalloy. Standard test method laboratory testing of metals for. Pdf thanks to their high corrosion resistance, super martensitic stainless steels are commonly used in the oil and gas industry, particularly in sour.
It should not be confused with the term stress corrosion cracking which is an anodic. Corrosion fatigue cf, hydrogen induced cracking hic and sulfide stress cracking ssc. Variation and degradation of p110 casing steel mechanical properties, due to sulfide stress cracking ssc in sour environments, was investigated using tensile and impact tests. Stress corrosion cracks propagate over a range of velocities from about 103 to 10 mmh, depending upon the combination of alloy and environment involved. Sulfide stress crackingnace mr01752002, mr0175iso 15156 651 te c h n i c a l new sulfide stress cracking standard for refineries don bush, principal engineer materials, at emerson process management fisher valves, is a member and former chair of a nace task group that has written a document for refinery applications, nace mr0103. Subsequent improvements in the metallurgy of steels for highpressure gas and oil wells and improved selection methods for highstrength alloys have been based on laboratory test methods. Environmentally assisted cracking of drill pipes in. The authors conducted extensive analyses to explore the effects of metallurgical factors on the resistance of line pipe steels to hydrogen induced cracking hic and sulfide stress cracking ssc. Pdf stress corrosion cracking scc behavior of 2205 duplex stainless steel dss in h2sco2. To our surprise, it was not true in the studied case. This article is reporting the sulfide stress cracking of stainless steel 410 in annealed condition. As a form of hydrogen stress cracking, ssc is a cracking mechanism in pipelines, facilities piping and any equipment that comes in contact with sour wet h2s service conditions. The history of dynamic straining in stress corrosion cracking studies and the evolution of the slow strain rate.
In recognition of the variation with temperature and with different materials this phenomenon is here called environmental cracking ec. Pdf sulfide stress corrosion study of a super martensitic stainless. The effect of cold work and strain ageing on the sulfide stress cracking resistance and mechanical properties of expanded tubular steels a laboratory study. Sulfide stress cracking of stainless steel 410 in sour. There are maximum acceptable h 2 s concentration limits in sale quality oil and gas, which require.
Pdf stress corrosion cracking of 2205 duplex stainless steel in h 2. Sulfide stress cracking an overview sciencedirect topics. In other words, it can support a stress of 80,000 psi with an elongation of less than 0. We propose a testing method for the evaluation of the threshold crack resistancek issc of pipe steels under the conditions of sulfide stress corrosion cracking.
Hydrogen induced cracking of low strength steels in. Wet hydrogen sulfide h2s cracking inspectioneering. To check its resistance to scc and ssc, several tests were performed. This paper analyzed the hsla pipeline steels stress corrosion behavior and mechanism which tested in the saturated solution of h2s.
A study on the mechanism of stress corrosion cracking of. H2s and hydrogen attackcorrosion refining, hydrocarbons. Which alloy is for sulfide stress and stress corrosion. This term should not be confused with stress corrosion cracking scs, since this is anodic in nature. The resistance to chlorideinduced stress corrosion cracking of uns n08031 was tested on ubend specimens according to astm g 30 for a testing time of 2000 hours. The presence of co2 in solution does not affect the fracture mechanism. Ricker, national institute of standards and technology stress corrosion cracking scc is a term used to describe service failures in engineering materials that occur by slow, environmentally induced crack propagation. Sulfide stress cracking is also called hydrogen sulfide cracking, sulfide cracking, sulfide corrosion cracking and sulfide stresscorrosion cracking. The mechanism of stressrelief cracking in the coarsegrained heataffected zone cghaz of a material can be investigated through stressrelaxation. Sulfide stress cracking ssc is a type of hydrogen cracking which presents a cathodic embrittlement mechanism. Their geometry is such that if they grow to appropriate lengths they may reach a critical size that results in a transition from the relatively slow crack growth rates associated with stress corrosion to.
The letter in conjunction with the number designates parameters such as the maximum yield strength and the minimum ultimate strength which for l80 pipe are 95,000 psi. Sulfide stress cracking nace mr01752002, mr0175iso. The slow strain rate stress corrosion cracking testa 50 year. Rotten eggs gas and inflammation in arthritic joints.
This article describes current industry practices to catalog features observed after sulfide stress cracking testing. Figure 41 three conditions necessary for scc scc cracking is usually oriented longitudinally in response to the hoop stress of the pipe, which is. Field history the production unit is installed as close to the oil wells as possible and is used to separate gas and water from the crude oil. It is a progressive type of failure that produces cracking at stress levels that are well below the materials tensile strength. The cracking usually occurs in the heataffected zone, which is the most susceptible area for crack initiation, due to solidstate metallurgical reactions during both heating and cooling thermal cycles. It should not be confused with the term stress corrosion cracking which is an anodic cracking mechanism.
Hic usually occurs due to the effects of aqueous hydrogen charging of steel in wet h2s refinery process environments. The values ofk issc are determined for various casing tubes made of different types of steel after heat treatment. The variation of the name is due to the lack of agreement in the mechanism of failure. A method for testing pipe steels under the conditions of. Sulfide stress corrosion cracking resistance was evaluated as per nace tm017796 method a using cylindrical test piece and a load ring. As described above, numerous theories exist on the causes of stressrelief cracking and these theories may all be valid under certain circumstances. The cracking resistance begins to deteriorate when fresh martensite exceeds 5 vol%. This article discusses catastrophic brittle fracture mechanisms due to eac. Sulphide stress cracking ssc is the biggest concern 9. 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. H2s partial pressure, 1 mpa and co2 partial pressure, 1 mpa. Stress corrosion cracking an overview sciencedirect topics.
However, it has now been shown to be present naturally in our bodies and reside in. Theories of hydrogenrelated cracking mechanisms are outlined with emphasis placed on sulphide stress cracking and hydrogen induced cracking in carbon and. Stressrelief cracking src is a major cause of weld failures in creep resistant, precipitation strengthened materials, such as ferritic steels, stainless steels, and nibased super alloys. Recent experience has demonstrated the risk of sscc and hic, sometimes known as hydrogen embrittlement he, of low strength steels subject to high residual stress derived from fabrication techniques.
Most of the published work is limited to strains less than 0. The mechanism of stressrelief cracking in a ferritic. Sulfide stress cracking of nickelcontaining lowalloy steels. Many changes have been made with austenitic stainless steels. Alloys which are commercially available and those which have modified metallurgical structures and. Reliability of dissimilar metal welds subjected to sulfide stress cracking vol. The applied stress was 70% and 100% of the yield strength ys of the material. Standard material requirements sulfide stress cracking resistant metallic materials for oilfield equipment contents 1. The major hazards of h 2 s are its ability to cause rapid damage to health or sudden death due to accidental exposure and metal integrity failure due to general corrosion or cracking. Standard material requirements sulfide stress cracking. A tensile stress higher than the threshold stress, frequently including some dynamic or cyclic component to the stress. Strain and sulfide stress cracking in pipeline girth welds. As we know that both form of cracking are due to the absorption of atomic hydrogen that is produced by.
Ssc is one of the many environmental cracking mechanisms resulting in pipeline steels exposed to aqueous sour service environments. The critical stress intensity factor for sulfide stress cracking, kissc, k issc of fully martensitic microstructures tempered to strength levels in the 620 to 725mpa range were 56 and 40mpam 12, whereas fully tempered bainitic microstructures with similar ys gave k issc values between 42 and 32mpam 12 garber, 1983. Other factors, such as ph, chloride concentration, and temperature also affect the potential for steel cracking. This phenomenon is generally termed sulfide stress cracking ssc 1 when operating at room temperature and stress corrosion cracking scc1 when operating at higher temperatures. The lattice diffusion of hydrogen is decreased by the addition of ni, whereas the subsurface hydrogen concentration remains constant in 5% nacl solution and decreases in nace tm0177 solution up to 5% ni.
Wet h 2 s corrosion can be a particularly dangerous form of corrosion because damage caused by it takes place on the interior of. The blistering damage tends to form parallel to the surface and to the direction of hoop stress. Sulfide stress cracking ssc is a form of hydrogen embrittlement which is a cathodic cracking mechanism. Sulfide stress corrosion cracking and hydrogen induced. Sulfide stress cracking ssc vs hydrogen induced cracking hlc posted in refining, hydrocarbons, oil, and gas. It is a complex process that is not completely understood because of the variety and complexity of mechanisms that can lead to embrittlement. Susceptible alloys, especially steels, react with hydrogen sulfide, forming metal sulfides and atomic hydrogen as corrosion byproducts. Hydrogen sulfide stress corrosion cracking in materials. Hydrogen induced cracking hic is a common form of wet h2s cracking caused by the blistering of a metal due to a high concentration of hydrogen. It can occur when carbonsteel equipment becomes exposed to wet h 2 s service environments, and it can come in several different forms.
Apart from sscc, h2s also cause other cracking, including stress corrosion cracking, hydrogeninduced cracking and stepwise cracking, stressoriented hydrogen induced cracking, soft zone cracking and galvanically induced hydrogen stress cracking. Large manganese sulphides were found in metallographic specimens not initiating any cracks. The effect of plastic strain on sulfide stress cracking. Hydrogen embrittlement is a function of the hydrogen absorption characteristics of the metal in the aggressive environment, which is the formation of molecular hydrogen from atomic hydrogen within the metal structure 160. Hydrogen embrittlement he also known as hydrogen assisted cracking hac and hydrogeninduced cracking hic, describes the embrittling of metal after being exposed to hydrogen. Corrosion of steels in sour gas environments international nuclear. Ssc is a form of spontaneous brittle breakdown in occurring in highstrength. The stress corrosion cracking behaviour of uns n08031 in. Mechanism of stress relief cracking in a granular bainitic. Sulfide stress cracking ssc resistance of casing steels with different alloying chemistries i. When sulfides are present in caustic solutions the scc has been reported to occur at lower temperatures. These tests were carried out on specimens, which were pretreated under the following conditions for 168 hours.