Sulfide Stress Cracking Research Articles

Influence of cooling path after rolling on sulfide stress cracking behavior for casing steel

Interrupted accelerated cooling (IAC) in comparison with normal air cooling after rolling is introduced into the production of the API-5CT-C110 casing steel. Sulfide stress cracking (SSC) resistance is improved by IAC processing without compromising strength. Multiple characterizations combined with hydrogen permeation tests are performed to reveal the mechanism of SSC behavior with respect to hydrogen interactions with metallurgical defects (grain boundaries, dislocations and precipitates). The results indicate a low dislocation density and increased amount of irreversible traps are responsible for the superior SSC resistance of the IAC specimen. A model of local hydrogen concentration is proposed to illustrate SSC susceptibility.

Microstructure Evolution of the Semi-Macro Segregation Induced Banded Structure in High Strength Oil Tubes During Quenching and Tempering Treatments.

C110 oil well casing tubes should have high strength and corrosion resistance which is commonly used for deep wells operation containing corrosive media. In this paper, the microstructure evolution of a kind of semi-macro segregation originated banded structure in casing tubes is studied under different heat treatments. It is shown that the characteristics of the banded structure will change significantly in subsequent hot working and heat treatment processes. For the hot-rolled ones, the banded structure is composed of pearlite plus bainite. After quenching, it evolves into martensite band with high concentration solute elements. Finally, the banded structure will change into a carbide banding under the following tempering process. The temperature and cooling rate of the tempering practice show an obvious effect on the final band structure. To improve anti-SSC (sulfide stress corrosion cracking) performance, the favorable QT (quenching and tempering) practice for C110 steel should be a higher tempering temperature and a quicker cooling rate, from which the banded structure defects can be decreased together with an obvious improvement of the tube wall hardness uniformity.

The Corrosion of Cast Duplex Stainless Steels in Seawater and Sour Brines

Modern duplex stainless steels have been in use since the early 1970s and cast versions of the wrought alloys were soon in demand for pumps and valves. Since that time a range of cast duplex stainless steels have been developed with a wide range of compositions, but all with approximately 50/50 austenite/ferrite phase balance and deliberate additions of nitrogen. This paper presents some comparative corrosion data on a range of cast duplex stainless steels, mainly in seawater. The differences in performance related to composition and microstructure are discussed. Corrosion data in lower chloride brines are also presented to show the limits of use of some lower alloyed duplex materials. In addition to oxidizing chloride solutions, some data are presented on cast duplex stainless steels in reducing brines containing H2S, where the main corrosion problem is sulfide stress corrosion cracking. Finally, the importance of using a suitable technical specification, over and above ASTM, combined with selecting a suitably skilled foundry in order to obtain satisfactory castings is discussed.

Material qualification of a 13Cr-L80 casing for sour conditions

Abstract This work aims to determine the material qualification of 13Cr-L80 casing for sour conditions which is of great importance to check the sulfide stress cracking susceptibility, confirm the range of applicable conditions and recommend anti-corrosion materials. First, the casing material was tested to judge whether its properties were normal. Secondly, the testing matrix was defined to determine actual casing exposure conditions. Thirdly, slow strain rate testing was used to screen the conditions. Fourthly, thirty-day tests of uniaxial tensile specimens were conducted to check for SSC susceptibility. The casing material satisfied API 5CT standards and could be used for slow strain rate testing and sulfide stress cracking testing. The testing matrix is intended to distinguish the combined effect of temperatures (41, 75, 140 °F), chloride levels (1000, 13 000 mg × L−1), pH (3.5, 5.5) and partial pressures of H2S (3.5 psi) in shut-in and flowing conditions. The slow strain rate testing showed a reduction of signs of embrittlement with increased temperature, suggesting that the mechanism is supported by sulfide stress cracking. The 13Cr-L80 passed field-specific qualification tests for sulfide stress cracking resistance in sour wells at maximum H2S partial pressures of 3.5 psi in the casing-tubing annulus. The API 5CT 13Cr-L80 casing application is in compliance with ISO15156/NACE MR0175 standards as long as the aggressiveness of the field conditions does not go beyond the envelope conditions tested (3.5 psi of H2S, pH 3.5, temperature of 41 or 75 °F).

Effects of chromium and tungsten on sulfide stress cracking in high strength low alloy 125 ksi grade casing steel

Chromium and tungsten contents were varied to produce three different 125 ksi grade casing steels, and their sulfide stress cracking (SSC) behaviors were evaluated using double cantilever beam testing. The effects of chromium and tungsten on the SSC resistance were clarified by microstructure analysis and hydrogen permeation test. Reducing the chromium content and adding tungsten significantly increased the number of irreversible traps and decreased the proportion of the Σ3 boundaries and high-angle grain boundaries. Moreover, the addition of tungsten led to the reduction of hydrogen permeability and diffusivity, resulting in the enhancement of SSC resistance.

Corrosion Behavior of Active-Screen Plasma Nitrided 17-4 PH (H1150D) Steel in H2S/CO2-Containing Environments

The presence of hydrogen sulfide (H2S) in typical oilfield environments promotes hydrogen absorption and subsequent failure of high-strength steels by sulfide stress cracking (SSC). Plasma nitriding is as a potential method to increase the resistance of the 17-4 PH to SSC, although further investigation is required to evaluate the corrosion resistance of the modified layer when it is exposed to H2S-containing environments. The aim of this study was therefore to evaluate the corrosion resistance of the 17-4 PH in typical oilfield environment. Samples were plasma nitrided at low (420°C) and high (500°C) temperatures and immersed in produced water with mixed H2S and CO2. The electrochemical data and scanning electron microscopy (SEM) micrographs showed that there were no detrimental effects on the corrosion resistance when plasma nitriding was performed at low temperature (420°C), whereas the integrity of the modified layer was compromised when an elevated temperature (500°C) was applied. The enhanced resistance to localized corrosion of the nitride case obtained after the low-temperature surface modification was attributed to the formation of a compound layer of mixed M4N/M2-3N, the inner section being more corrosion resistant than the outer part, as revealed by SEM micrographs.

Effect of tempering temperature at high temperature zone on sulfide stress cracking behavior for casing steel

Three tempering temperatures at high temperature zone (690 °C, 700 °C and 710 °C) are selected into the quenching-and-tempering processes and performed on the rolled Cr-Mo steel to develop API-5CT-C110 casing steels. Effect of tempering temperature on sulfide stress cracking (SSC) behavior is quantitatively evaluated and further explored by characterizing the microstructure and crystallography. The results show that the strength of steel decreases with tempering temperature, but the SSC susceptibility is reversely varied. EBSD analysis indicates that the steel tempered at lower temperature (690 °C) generates more grains with high Taylor factors, which are difficult to yield, leading to the increasing of dislocation density and more susceptible to SSC.

Sulfide stress cracking assessment of low-alloy L80 casing steel in H2S environment

Purpose This paper aims to evaluate the sulfide stress cracking (SSC) resistance of L80 casing steels with different alloying chemistries (e.g. Ti-B and Mn-Cr-Mo) by correlating the reduction in area ratio with the mechanical property, inclusion and carbide. Design/methodology/approach SSC tests were conducted in 5.0 Wt.% sodium chloride and 0.5 Wt.% acetic acid solution saturated with H2S using constant load tensile method. The microstructure and fracture morphology of the steel were observed using scanning electron microscope. The inclusion and carbide were identified by energy dispersive spectroscopy and auger electron microscope. Findings Among all the testing steels, electric resistance welding (ERW) L80-0.5Mo steel demonstrates the highest SSC resistance because of its appropriate mechanical properties, uniform microstructure and low inclusion content. The SSC resistance of L80 steels generally decreases with the rising yield strength. The fracture mode of steel with low SSC resistance is jointly dominated by transgranular and intergranular cracking, whereas that with high SSC resistance is mainly transgranular cracking. SSC is more sensitive to inclusions than carbides because the cracks are easier to be initiated from the elongated inclusions and oversized oxide inclusions, especially the inclusion clusters. Unlike the elongated carbide, globular carbide in the steel can reduce the negative effect on the SSC resistance. Especially, a uniform microstructure with fine globular carbides favors a significant improvement in SSC resistance through precluding the cracking propagation. Originality/value The paper provides the new insights into the improvement in SSC resistance of L80 casing steel for its application in H2S environment through optimizing its alloying compositions and microstructure.

Improvement of Low-Alloy Pipe Steel Sulfide Stress Cracking Resistance

The influence of sheet microstructure formed by various thermomechanical processing schedules on sulfide stress cracking (SSC) resistance under uniaxial tension for low-alloy pipe steels grades X42–X65 is studied. A favorable role is established for substitution of a ferritic-pearlitic by a ferritic-bainitic microstructure and improvement of structural component dispersion is established. The favorable effect is facilitated by using high intensity post-deformation cooling from the austenite region. It is shown that segregation bands and non-metallic inclusions in a sheet axial zone do not affect the duration of specimens withstanding SSC, but they can lead to formation of hydrogen cracks (HIC) on a specimen surface that is a defective feature. In order to prevent crack formation in a specimen surface and premature failure it is necessary to lay down high specifications for specimen gauge length and fillet surface quality.

Transcriptome and proteome analyses of red blood cells from rainbow trout challenged with viral haemorrhagic septicaemia virus

Chromium and tungsten contents were varied to produce three different 125 ksi grade casing steels, and their sulfide stress cracking (SSC) behaviors were evaluated using double cantilever beam testing. The effects of chromium and tungsten on the SSC resistance were clarified by microstructure analysis and hydrogen permeation test. Reducing the chromium content and adding tungsten significantly increased the number of irreversible traps and decreased the proportion of the Σ3 boundaries and high-angle grain boundaries. Moreover, the addition of tungsten led to the reduction of hydrogen permeability and diffusivity, resulting in the enhancement of SSC resistance.

Influence of PWHT on the sulfide stress cracking susceptibility of 9%Ni low carbon steel

The 9Ni steel low carbon steel is usually applied to pipes, pressure vessels and forged parts working at cryogenic temperatures, due to its high toughness at −196 °C and mechanical strength. Recently, this material was selected to facilities for storage and re-injection of CO2 gas in modern off shore oil and gas platforms. In this new application the steel may be subjected to high pressures in as environment with condensed water, CO2 and traces of H2S. The effect of such a harsh environment on the simulated heat affected zone (HAZ) was investigated by slow strain rate tensile (SSRT) tests. Two post weld heat treatments (PWHT) were reproduced, single tempering (ST) at 575 °C and double tempering (DT) at 670 °C (2 h) and 600 °C (2 h). Specimens without PWHT were more susceptible to sulfide stress cracking (SSC), while the single tempering at 575 °C decreased both the hardness and the SSC susceptibility. Double tempering also increased the resistance to SSC, but was not more effective than the single tempering. As general conclusion, PWHT is strongly recommended to 9Ni low carbon steels subjected to H2S containing environments.

Important Factors on the Failure of Pipeline Steels with Focus on Hydrogen Induced Cracks and Improvement of Their Resistance: Review Paper

Currently, thousands of kilometers of pipeline steels are transferring hydrocarbon fluids such as oil and natural gas in the world. Due to the fact that these pipes transport corrosive and high-pressure fluids from harsh environments, they are damaged and eventually degraded. Previous studies showed that sulphide stress cracking, hydrogen induced cracking (HIC) and stress corrosion cracking are the main destructive factors in these types of pipes. This paper focused on the HIC related failure in pipeline steel, since the role of texture and grain boundary character has not been completely recognized. Moreover, if pipeline damage is occurred by hydrogen cracks, besides the environmental pollutions, it will cost a lot to repair or replace the damaged pipeline steels. In this research, the factors influencing the initiation and propagation of the HIC cracks, such as hydrogen traps, inclusions, precipitates, microstructure and texture of steel have been investigated. Also, the existing solutions for improving the steel resistance to the HIC have been investigated based on the control of micro-alloy elements, texture and grain boundary engineering. For instance, some special dominant texture components and coincidence site lattice boundaries decrease the HIC susceptibility by providing the resistant path for crack propagation.

Effect of Cooling Rate on the Formation of Nonmetallic Inclusions in X80 Pipeline Steel

Nonmetallic inclusions have a strong influence on the hydrogen-induced cracking (HIC) and sulfide stress cracking (SSC) in pipeline steels, which should be well controlled to improve the steel resistance to HIC and SSC. The effects of cooling rate on the formation of nonmetallic inclusions have been studied both experimentally and thermodynamically. It was found that the increasing cooling rate increased the number density and decreased the size of the inclusions, while the inverse results were obtained by decreasing the cooling rate. Furthermore, as the cooling rate decreased from 10 to 0.035 K/s, the inclusions were changed from Al2O3-CaO to Al2O3-CaO-MgO-CaS. At a high cooling rate, the reaction time is short and the inclusions cannot be completely transformed which should be mainly formed at high temperatures. While, at low cooling rate, the inclusions can be gradually transformed and tend to follow the equilibrium compositions.

Sulfide Stress Corrosion Cracking Behavior of G105 and S135 High-Strength Drill Pipe Steels in H2S Environment

Slow strain rate testing was employed to investigate the sulfide stress corrosion cracking (SSCC) behavior of low-carbon high-strength drill pipe steels (G105 and S135) in the simulated drilling environment containing H2S. Results reveal that both G105 and S135 steels have a high SSCC susceptibility in the simulated drilling environment containing H2S. In the range of experimental slow strain rate, the SSCC sensitivity of drill pipe steel increases with the decrease in slow strain rate, and the ductility and fracture properties of drill pipe steels also decrease obviously. With the increase in the steel strength, the SSCC sensitivity of the drill pipe steel increases, and the S135 drill pipe steel has higher SSCC sensitivity than G105. There is no obvious plastic deformation on the fracture surface of G105 and S135 steels in H2S solution. The cracks of fracture sprout on the surface of the specimen, the instantaneous fracture zone is in the middle, and the fracture can be divided into the cracking and the final fracture zone. The SSCC mechanisms of two drill pipe steels are hydrogen embrittlement. The hydrogen enters the steel and reduces the binding force of the iron atom, resulting in cleavage fracture.

Effect of Postweld Heat Treatment on the Sulfide Stress Cracking of Dissimilar Welds of Nickel-Based Alloy 625 on Steels

Alloy 625 overlay on 2.25Cr-1Mo (F22) Steel or AISI 8630 is used in oil and gas industry for corrosion protection. In some cases, F22/625 or 8630/625 interface is possibly exposed to the H2S-contai...

Corrosion Evaluation and Material Selection for Supercritical Water Reactor Used for Heavy Oil Upgradation

Supercritical water is uniquely a green medium for diverse applications because of its changing nature from polar to non-polar. Owing to this property, it is being considered for heavy oil upgradation since it dissolves both organics (oil) and hydrogen while inorganics behave conversely. However, because of the high pressure and temperature (22.1 MPa, 374 °C), corrosive environment (chlorides, sulfides and salt deposition) and stresses involved, there are serious concerns encountered while utilizing supercritical water in reactors. These include change in the component-material microstructure due to hydrogen ingress, sulfide stress corrosion cracking and salt deposition leading to pitting and de-alloying. Various alloys such as ferritic–martensitic steels, austenitic stainless steels, Ti-, Ni- and Zr-based alloys have been used, while new alloys and materials are continuously being investigated to considerably help abate these problems and ultimately improve the life of reactors. Despite significant past efforts in material development, reactors still suffer from these problems and challenges. This review assesses materials selection, the current progress in material development as well as their potentials in ameliorating reactors resistance to oxidation, pitting, embrittlement, etc. This study aims to improve understanding of material selection for supercritical water reactors based on the corrosive environment of the reactor and hence help engineers to make insightful decisions in selecting material for the specific corrosive environment. Schematic illustration of materials susceptibility in supercritical water reactor

НАУЧНЫЕ ОСНОВЫ РАЗРАБОТКИ И МЕТОДОЛОГИЯ СОЗДАНИЯ СТАЛЕЙ ДЛЯ ПРОИЗВОДСТВА НЕФТЕПРОМЫСЛОВЫХ ТРУБ ПОВЫШЕННОЙ ПРОЧНОСТИ И КОРРОЗИОННОЙ СТОЙКОСТИ

The authors carried out the survey of the crashworthiness of the oil-field and transportation equipment and noted the significant (by times, and sometimes dozens of times) exceeding of the allowable reliability index of the pipeline systems according to the values of the specific failure rate (item/km/year). It is shown that the main reason for pipe degradation and fracture is the internal corrosion which, depending on the composition of produced fluids, is manifested by one predominant type or the combination of several types of stress-corrosion fracture: hydrogen cracking, sulfide stress corrosion cracking, carbon dioxide, sulfide, and bacterial corrosion. Based on the generalization and systematization of the results of numerous research and applied works on the development and utilization of new pipe steels with the increased strength and corrosion resistance, the main scientific ideas of the formation of steel corrosion resistance in the highly aggressive oil-field fluids are proposed. The authors developed the methodology and offered the sequence of measures (algorithm) to solve set problems on the development of steels for production of oil pipes with higher mechanical properties and the resistance to stress-corrosion fracture. A list of necessary research, tests, and requirements to the product quality is defined. The authors proved the rationality of used approaches, methods, and decisions on the alloying, microalloying, modifying, and selection of the structural condition of the developed steels and on the technology of pipe production. The paper presents the examples of the development of new steels with the increased strength and corrosion resistance and, consequently, for the efficient solution of issues of the improvement of the performance characteristics of oil-and-gas pipeline and oil-well tubes.

Steel for gas and oil pipelines resistant to destruction in hydrogen sulphide-containing media

About a third reserves of the natural gas and oil contain H2S impurities, which, in the presence of moisture, form an acidic medium and can lead to pipeline destruction by the mechanisms of hydrogen-induced cracking (HIC) and sulfide stress cracking (SSC). With the growing number of hydrocarbon fields being developed with a high content of H2S, the demand for gas and oil large diameter pipes grade from ВМS to Х70MS with high resistance to HIC and SSC increases. Comprehensive studies have been carried out in laboratory and industrial conditions to determine the effect of the chemical composition and thermomechanical processing on the microstructure, mechanical properties and resistance to HIC of rolled plates from low-alloy pipe steels. Optimal concentration of segregating elements (С ≤ 0.06%, Mn ≤ 1.00%), and schedules of accelerated cooling after controlled rolling (Тsc ≥ Ar3; Тfc = 520±30°C; Vc ≥ 20°C/с) provide the high resistance to destruction in H2S-containing media due the formation of a homogeneous microstructure without developed central segregation heterogeneity was determined. According to the research results, the technology for manufacturing of plates for large-diameter pipes grade X52MS, X56MS, X60MS, and X65MS ordered for sour service was developed.

Providing resistance to sulfide stress corrosion cracking of pipelines welded joints by selection of welding parameters

Sulfide stress cracking (SSC) is one of the most dangerous types of pipelines destruction. Thermal impact of the welding process drives to heterogeneity of the microstructure and properties of the metal, which can lead to cracking of pipeline welded joints. Resistance to SSC of welded joints is determined by the thermal cycle of welding and cooling rate in the temperature range of austenite transformation. Due to performed studies based on simulation of welding heating the recommended range of cooling rates of 10–30 ° C/s was established, in which the resistance to SSC of welded joints is ensured. To calculate the cooling rates in coarse grained heat affected zone (CGHAZ) finite-element models of heat distribution were developed for longitudinal multi-electrode submerged arc welding (SAW) and multi-pass girth welding of pipes. Using the developed welding models, it was found that in order to achieve the cooling rate in CGHAZ it is necessary to reduce heat input up to 15-30% during multi-electrode SAW process of longitudinal welds of pipes . For multi-pass girth welding it is necessary to preheat the edges to be welded up to 100-300 °C depending on type of welding (GMAW or SMAW) and pipe wall thickness.

New approach to development and manufacturing technologies of duplex steel

We conducted a brief review of current production and application of duplex and super duplex steels for manufacture of equipment exposed to the hazard of sulphide stress-corrosion cracking, sea water and other corrosive environment. The super duplex steel with enhanced corrosion-mechanical characteristics in comparison with the known steels of austenitic-ferritic class was developed. Based on the concepts of formation of a special structure of two-phase austenitic-ferritic steels in the process of crystallization, the possibilities of compositional, technological, thermal and special impact techniques are considered and advanced ways of controlling physical, chemical, structural homogeneity and properties of super duplex steels are developed. Electroslag remelting with the application of low-frequency alternating current provides effective control over the length of the two-phase area, the size of the primary dendrites of the austenitic and ferritic phases, the average distance between their axes, the parameters of the crystallizing cell, the development of liquation phenomena and the size of the growing non-metallic phases. Within framework of the proposed approach, the thermodynamic and kinetic conditions for the formation and growth of hardening phases are assessed, a new composition and a complex technology for the manufacture of corrosion-resistant super duplex steels for gas and oil production equipment has been developed. Thermodynamically stable, having sizes of 30-300 nm, niobium nitrides and carbonitrides are located inside the grains of the ferritic phase. At the same time, the sigma phase and chromium carbide precipitates at the intergrain boundaries are not observed. The results of the determination of mechanical and corrosion properties in accordance with the NACE TM 0177 standard (method A), tests of corrosion witness-samples in field conditions demonstrate the advantages and prospects of using new super duplex steel for the manufacture of oil and gas production equipment operating in an environment with high H2S content and CO2 under significant mechanical loads, without the risk of brittle fracture.