Sulfide stress cracking of a pipeline weld in sour gas. The effect of low h2s concentrations on welded steels march. Sulfide stress cracking of nickelcontaining lowalloy steels. 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.
Environmentally assisted cracking scc, corrosion fatigue, hydrogen induced, sulfide stress cracking, selective seam corrosion and. Susceptibility of pipeline girth welds to hydrogen embrittlement and. Sulfide stress cracking an overview sciencedirect topics. Vintage and newer pipelines have the capacity to plastically deform allowing local. Performance of welded highstrength lowalloy steels in sour. A sour service pipeline environment is defined by nace international specification mr017 as fluids containing water and hydrogen sulfide h2s that is a total pressure of 0. Corrosion is related to the susceptibility of the material to the environment, while stresses may be. Kermani m b, harrop d, truchon m l r and crolet j l. Without welding, nothing is possible which relates aircraft to skyrocket, the pipeline to highways, cars to workplace constructions. The tests were supplemented by potentiodynamic polarization curves and hydrogen permeation measurements. What causes stress corrosion cracking in pipelines. Strain and sulfide stress cracking in pipeline girth welds twi. Environmentallyassisted cracking scc, corrosion fatigue, hydrogen induced, sulfide stress cracking, selective seam corrosion manufacturingrelated anomalies lack of fusion, cold welds, stitching, and hook cracklike features a description of factors that drive their stable growth leading to failures.
Excellent hydrogeninduced cracking hic and sulfide stress corrosion cracking sscc resistance. H 2 s damage can lead to rapid and extensive damage to metals, including uniform corrosion, pitting, and stepwise cracking. Currently, the main technical standards for oil and gas conveying steel linepipes are api spec 5l, dnvosf101, iso 3183 and gbt 9711, etc. Welding onto a gas pipeline in active operation is. In carbon steel line pipe material, microalloy additions make welds resistant to. Dec 19, 2019 sulfide stress cracking ssc is a type of hydrogen cracking which presents a cathodic embrittlement mechanism. Sulphide stress corrosion cracking is a major problem to be analysed during pipeline girth welds.
Hydrogen embrittlement he also known as hydrogen assisted cracking hac and hydrogeninduced cracking hic, describes the embrittling of metal after being exposed to hydrogen. The consequences of cracks formed on the oil and gas pipelines weld joints. Sulfide stress cracking susceptibility of welded x60 and. Element performs sulfide stress cracking ssc testing of metals subject to cracking under the combined action of tensile stress and corrosion in the presence of water and h2s, in compliance with nace tm0177 iso 15156 standards. Weld metal corrosion is normally attributed to the differences in composition and to differences in electrochemical potentials between the parent metal, heataffected zone haz, and weld metal. Guidelines for developing a procedure for the weld repair of. There are many types of cracks, including stress corrosion cracking scc, fatigue cracking, hydrogeninduced cracking hic and sulfide stress cracking ssc. Welding research effect of welding parameters and h2s.
The rapid cooling can be compensated by increasing heat input, but the increased heat input can promote weld penetration and the possibility of meltthrough. Sulfide stress cracking is the worst type of corrosion in the presence of hydrogen sulfide. Wet hydrogen sulfide h2s cracking inspectioneering. For gas pipelines, where the water will be condensed water, it is reasonable to calculate the ph based on the operating temperature and pressure and the concentration of carbon dioxide. Webcorr provides corrosion consultancy services, corrosion expert witness and corrosion short courses for inhouse training, online and distance learning.
It can occur when carbonsteel equipment becomes exposed to wet h 2 s service environments, and it can come in several different forms. Weld hardness was characterized with rockwell c and vick. Thus, suitable welding procedures must ensure optimal haz hardness, no meltthrough, and proper heat input. This prompted for a failure investigation to be carried out. Hydrogen sulfides corrosiveness can result in sulfide stress corrosion cracking in the welded material. A permanent repair has been carried out by welding the same clamp and the leak was still there. When the pipelines are exposed for many years to wet h2s environments, they can fail due to hydrogen embrittlement. Therefore, it is a source of hydrogen ions and is corrosive. Although it is related to the welding process, the crack occurs in the base material, not in the weld material. Effects of microstructure on the sulfide stress corrosion. Sour cracking hic, sulfide stress corrosion cracking sscc environmentally assisted cracking can also occur internally in pipelines. Welding research effect of welding parameters and h2s partial. For oil field equipment, the nace mr0175 standard recommends a maximum hardness of 22hrc approximately 248 hv in carbon and low alloy steels to avoid sulphide stress corrosion cracking sscc. Sulfide stress cracking domains for carbon steel pipelines.
It involves the ingress of hydrogen into a component, an event that can seriously reduce the ductility and loadbearing capacity, cause cracking and catastrophic brittle failures at stresses below the yield stress of susceptible materials. Rosen 15 types of pipeline cracks inspection solutions. Providing resistance to sulfide stress corrosion cracking of pipelines. In designing pipeline and process equipment for handling sour containing h 2 s products, limitations are frequently imposed on material hardness. Therefore, it is important to ensure this high level of toughness in the welded joint. This book skillfully explains the fundamental science and. Review and critical assessment of hardness criterion to. This type of cracking is also known as underbead cracking, toe cracking, or delayed crack. The susceptibility to hydrogen embrittlement of the welds could be reduced significantly by subjecting the welds to 600c2 h tempering. When they are in good working order, they deliver fuel to meet the evergrowing demand for energy around the world. It should not be confused with the term stress corrosion cracking which is an anodic cracking mechanism.
Susceptibility study to hydrogen embrittlement of welded. The effect of peak weld hardness was examined by using three welding conditions. Manufacturing related anomalies lack of fusion, cold welds, stitching, and hook cracklike features operational driven fatigue cracks in the body of the pipe and weld toe. Following aqueous corrosion reactions in the presence of h2s on the pipe internal surface, atomic hydrogen is produced and absorbed in the pipe steel. Performance of welded highstrength lowalloy steels in. This is a type of deterioration which can be linked to corrosion and corrosioncontrol processes.
A special case is arc welding, in which the hydrogen is released from. Analysis of stress corrosion cracking of x65 oil pipeline stress. Hydrogen sulfide is particularly dangerous to equipment when moisture is present. The most typical forms for cracking are environmentally assisted, manufacturing related, and operational driven. Pipelines for oil and gas, manufactured in highstrength lowalloy steels hsla, such api pipes, promote high levels of strength and fracture toughness. Welding and qualification of microalloyed hsla steel weldments, chairman malcolm gray, 1990, pg 327. The most common conditions for these are sour environments. Scc occurs as a result of a combination between corrosion and tensile stress. There are instances in which such pipelines gave a long service in sour atmospheres. Review and critical assessment of hardness criterion to avoid sulfide stress cracking in pipeline welds. Sulfide stress cracking susceptibility of local hard areas in carbon.
The consequences of cracks formed on the oil and gas. Susceptible alloys, especially steels, react with hydrogen sulfide, forming metal sulfides and atomic hydrogen as corrosion byproducts. The x65 grade pipe steel consisted of finegrained ferrite and a small volume fraction of pearlite. Hydrogen sulfide h 2 s is a colorless, flammable, and extremely hazardous gas with a strong rotten egg odor. This paper reports the sulfide stress corrosion cracking ssc behavior of line pipe steel investigated using the ssc test method in nace standard tmo17777, testing of. Welding processes are utilized to produce pipeline segments seam and spiral welds and join pipeline segments girth welds in the field. Corrosionpedia what is sulfide stress cracking ssc. Most buried pipelines that have been in service for five or more years experience numerous. The major problem related to welding is the occurrence of crack at high temperatures during solidification.
Ssc testing, proof ring, stress corrosion cracking. Sulfide stress cracking of nickelcontaining lowalloy. For this purpose, steel welding was carried out normal to the rolling direction using a 60 single vjoint design. Pdf the consequences of cracks formed on the oil and gas. The critical stress sc values of these three microstructures were determined. Welding research numerical simulation of sleeve repair. Mar 16, 2020 excellent hydrogeninduced cracking hic and sulfide stress corrosion cracking sscc resistance. In this work, the hydrogen sulfide stresscorrosion cracking ssc susceptibility of a welded api x80 pipeline was investigated. Crack growth in a welded microalloyed steel under sulfide. Sulfide stress corrosion cracking and fatigue crack growth. However, hydrogen sulfide forms a weak acid when dissolved in water. Welding needs specified for x80 offshore line pipe oil.
Review and critical assessment of hardness criterion to avoid. When they fail due to stress corrosion cracking, they can wreak environmental havoc. Highstrength steels with improved sulfide stress cracking resistance. Consumables for sour service typically, highstrength carbon steel, grade x70, is used for such subsea jobs.
Our pre and post weld heat treatment pwht services provides the clients with. Sulfide stress cracking is the cracking of a metal under the combined action of tensile stress and corrosion in the presence of water and hydrogen sulfide a form of hydrogen stress cracking. Stress corrosion cracking of pipelines electrochemistry. Welding equipment and consumables for the pipeline industries. The influence of chemical composition and microstructure of api linepipe steels on hydrogen induced cracking and sulfide stress corrosion cracking. After welding, compact modifiedwedge opening loading mwol fracture mechanics specimens were machined and loaded to an applied.
Minimizing hydrogen cracking critical for cr pipeline. There are no major differences in welding x70 material compared to lowergrade steel, such as x65. Sulfide stress cracking mostly occurs in very highly acidic environments. Published on may 23, 2017 may 23, 2017 43 likes 5 comments. Sulfide stress cracking ssc is the failure of steel caused by the simultaneous action of stress and hydrogen absorbed from corrosion. Therefore, for verification that x80 material has acceptable resistance to either hic, sulfide stress corrosion cracking, or stress oriented hic in sour service, fullscale tests must be carried out. V arious forms of cracks, cracklike indications and seam weld anomalies are known to be present on pipelines, which could become a safety concern to their safe operation. Ssc proof rings caltech engineering services india manufacture and supply proof ring to test and accurately determine the resistance to sulfide stress corrosion cracking ssc and stress corrosion cracking of metals in h2s environment or service. When sulfide is present, this type of brittle failure is known as sulfide stress cracking ssc, and it has been established as a particular case of he. Stress corrosion cracking scc is a type of environmentallyassisted cracking eac, or the formation of cracks caused by various factors combined with the environment surrounding the pipeline. Role of microstructure on sulfide stress cracking of oil. This paper reports the sulfide stress corrosion cracking ssc behavior of line pipe steel investigated using the ssc test method in nace standard tmo17777, testing of metals for resistance to. Providing resistance to sulfide stress corrosion cracking of pipelines welded joints by selection of welding parameters. V arious forms of cracks, long seam weld anomalies and dents are known to be present in pipelines, which can become a safety concern over the operational life of the pipeline.
Guidelines for developing a procedure for the weld repair of process pipelines in oil refineries. Then the defected spool pipe was replaced by a 4m new spool pipe and the pipeline was back to. Heat affected zone haz cracking figure 5 is characterized by separation that occurs immediately adjacent to the weld bead. Asme boiler and pressure vessel code, section ix welding and brazing qualifications. Explains why pipeline stress corrosion cracking happens and how it can be prevented pipelines sit at the heart of the global economy. The iso methodology requires an estimate of the ph of the water that will be present.
Sulfide stress corrosion cracking and fatigue crack growth of welded. They occur in the base material of the pipe, in welds and in heataffected. The sulfide stress cracking ssc resistance of api x65 grade steel weldment has been studied using ssc test in nace tm0177 method a and the applied load was 72108 % of yield strength. Sulfide stress cracking is prevented by minimizing the hardness and strength of. Wet h 2 s corrosion can be a particularly dangerous form of corrosion because damage. The critical stress sc values of these three microstructures were determined experimentally to be 1008, 1190, and.
The effect of cold work and strain ageing on the sulfide stress cracking resistance and mechanical properties of expanded tubular steels a laboratory study. Guidelines for developing a procedure for the weld repair. Ssc testing, proof ring, stress corrosion cracking, sulfide. Sulfide stress cracking ssc is a form of hydrogen embrittlement which is a cathodic cracking mechanism.
Sulfide corrosion cracking of line pipe for sour gas service, nace, corrosion 37 1, january 1981. Sulfide stress cracking ssc behavior of three microstructures, i. Processes that can lead to this include cathodic protection, phosphating, pickling, and electroplating. Ppim 2019 managing cracks and seam weld anomalies on. Ppim 2019 managing cracks and seam weld anomalies on pipelines. Sulfide stress cracking is a form of hydrogen embrittlement that occurs in highstrength steels and in localized hard zones in weldment of susceptible. Proceedings of the asme 2016 pressure vessels and piping conference.
Safe weld hardness levels to insure long service life in offshore pipelines, offshore technology conference, may, 1972, houston texas, paper otc 1571. The susceptibility of api x60 and x65 longitudinal weld beads to sulfide stress cracking ssc has been evaluated using slow strain rate tests ssrt in the nace solution saturated with hydrogen sulfide h 2 s. Hydrogen embrittlement can occur during various manufacturing operations or operational use anywhere that the metal comes into contact with atomic or molecular hydrogen. Sulfide stress cracking ssc is a type of hydrogen cracking which presents a cathodic embrittlement mechanism. Abstract for sour service conditions there are stringent weldment hardness requirements that must be satisfied in order to minimise the risk of sulfide stress corrosion cracking ssc in service. Sulfide stress cracking susceptibility of welded x60 and x. The most typical forms of cracking and seam weld anomalies are environmentally, manufacturingor operational related, such as stress corrosion cracking, corrosion fatigue cracking, hydrogen. Sulfide stress corrosion cracking and fatigue crack growth of welded tmcp api 5l x65 pipeline steel. In year 2012 the pipeline failed suddenly by cracking along the heat affected zone of the spiral weld.
Welding equipment and consumables for pipeline industries from lincoln electric. The susceptibility of welded api 5l x70 and x80 steels to sulfide stress cracking ssc was investigated using two applied stresses and three h 2s concentrations. Strain and sulfide stress cracking in pipeline girth welds. Therefore, for verification that x80 material has acceptable resistance to either hic, sulfidestress corrosion cracking, or stressoriented hic in sour service, fullscale tests must be. Six unstrained, cross weld, four point bend sulfide stress corrosion cracking specimens were machined from the pipe at positions adjacent to the 3 oclock and 9 oclock positions from which the strain specimen blanks had been extracted specimens scc16. This term should not be confused with stress corrosion cracking scs, since this is anodic in nature. It is a complex process that is not completely understood because of the variety and complexity of mechanisms that can lead to embrittlement. After welding, compact modifiedwedge opening loading mwol fracture mechanics specimens were machined and loaded to. The susceptibility of girth welds to sulphide stress cracking ssc and hydrogen embrittlement he were evaluated for api grade x80 and x56 steels, both for. Characteristics of sulfide stress cracking of high strength pipeline. Managing cracking and seam weld anomalies in pipelines clarion.
Characteristics of sulfide stress cracking of high strength pipeline steel weld by heat input. But, higher weld metal hardness and a martensitic weld microstructure mean that even lower hydrogen levels are necessary to prevent hydrogeninduced cracking. The effect of strain on the suspectability of pipeline. As a form of hydrogen stress cracking, ssc is a cracking mechanism in pipelines, facilities piping and any equipment. This paper describes work performed under a short study programme into the sulfide stress corrosion cracking behaviour of samples taken from a pipe girth weld.