Stress Oriented Hydrogen Induced Cracking Research Articles

Hydrogen Embrittlement Behavior of API X70 Linepipe Steel under Ex Situ and In Situ Hydrogen Charging.

This study investigates the hydrogen embrittlement behavior of API X70 linepipe steel. The microstructure was primarily composed of a dislocation-rich bainitic microstructure and polygonal ferrite. Slow strain-rate tests (SSRTs) were performed under both ex situ and in situ electrochemical hydrogen charging conditions to examine the difference between hydrogen diffusion and trapping behaviors. The ex situ SSRTs showed almost the same tensile properties as air and a limited brittle fracture confined to near the surface. In contrast, the in situ SSRTs showed an abrupt failure after the maximum tensile load, leading to a brittle fracture across the entire fracture surface with stress-oriented hydrogen-induced cracking (SOHIC). The crack trace analysis results indicated that SOHIC propagation paths were influenced by localized hydrogen accumulation due to high-stress fields. As a result, the dominant hydrogen embrittlement mechanisms, such as hydrogen-enhanced localized plasticity (HELP) and hydrogen-enhanced decohesion (HEDE), changed. These findings provide critical insights into the microstructural factors affecting hydrogen embrittlement, which are essential for the design of hydrogen-resistant steels in hydrogen infrastructure applications.

Addressing Hydrogen Sulfide Corrosion in Oil and Gas Industries: A Sustainable Perspective

In the oil and gas industry, the corrosion attributed to hydrogen sulfide (H2S) is one of the most significant challenges. This review paper systematically investigates the diverse facets of H2S corrosion, including its sources, corrosion locations, mechanisms, and resultant corrosion products. Understanding different forms of H2S corrosion, such as stress-oriented hydrogen-induced cracking (SO-HIC), sulfide stress cracking (SSC), and hydrogen-induced cracking (HIC), provides a thorough comprehension of these phenomena. The paper discusses critical factors influencing H2S corrosion, such as temperature, flow rate, pH, and H2S concentration, highlighting their implications for sustainable practices in the oil and gas sector. The review emphasizes the significance of monitoring and mitigation strategies, covering continuous monitoring, applying corrosion inhibitors, selecting materials, and conducting thorough data analysis and reporting. Furthermore, the role of training in fostering a sustainable approach to H2S corrosion management is highlighted. This exploration advances the overarching goal of sustainable development in the oil and gas industries by providing insights into understanding, monitoring, and mitigating H2S corrosion. The findings presented here offer a foundation for developing environmentally conscious strategies and practices to guarantee the long-term viability and flexibility of refinery operations.

New insight into the fitness of 13Cr stainless steel in H2S-containing environment at high temperature

In the oil and gas industry, the selection of tubing and casing materials is required to follow international standard ISO 15156. However, it does not provide guidance on selecting stainless steel materials for H2S-containing wells above 232 °C, which raises uncertainty about the suitability of 13Cr steel. This work focuses on investigating the mechanical degradation and failure mechanisms of 13Cr stainless steel exposed to high-temperature conditions and proposed a creep constitutive model. Then, the corrosion and cracking mechanisms of 13Cr stainless steel at temperatures ranging from 150 °C to 350 °C were elucidated. Results show that 13Cr stainless steel meets the current material selection criteria (GB/T34907-2017) for mechanical properties and creep resistance. In the range of 150–250 °C, the localized corrosion is dominant, and stress-oriented hydrogen-induced cracking occurs at 150 °C. As the temperature increases from 250 °C to 350 °C, although the maximum value of uniform corrosion rate is as high as 0.2960 mm/a, the cracking does not happen. Therefore, with the implementation of suitable protective measures, 13Cr stainless steel can be utilized in wells that the temperatures ranging from 250 °C to 350 °C and H2S partial pressures up to 0.17 MPa. This aligns with the global carbon-neutral agenda.

A Comparative Investigation of the Effect of Microstructure and Crystallographic Data on Stress-Oriented Hydrogen Induced Cracking Susceptibility of API 5L X70 Pipeline Steel

In this research, stress-oriented hydrogen induced cracking (SOHIC) test was carried out on a 50 mm thickness of a commercial API 5L X70 steel plate. The evolution of microscopic features such as phase, boundary, interface, grain, and crystallographic data was analyzed before and after SOHIC, in order to comprehend the effect of crystallographic orientation on SOHIC propagation. Chemical composition and previous thermomechanical processing even finish rolling temperature and cooling rate determine the ferrite matrix microstructure. A recrystallized ultrafine ferrite grain with about 3–5% degenerated pearlite dispersed in the microstructure was characterized, called as-received specimen. The average lattice strain and dislocation density was calculated first using multiple Gaussian peak-fitting method from XRD pattern. Electrochemically charged combination mixed H2S-CO2 solution, constant hydrogen injection, and external loading were applied to tensile specimen, in order to simulate the H2S and CO2 environment. The results show that local misorientation and Taylor factor analyses predicted the possibility of hydrogen crack nucleation especially at boundaries and interfaces. Moreover, SOHIC crack propagation occurred along the mid-thickness of the cross section of steel plate along the ferritic boundaries, pearlitic colonies, and ferrite-cementite interfaces. Moreover, the crack propagated along distorted {110} and {001} grains, indicating a strong strain gradient towards the boundaries. The analysis of XRD patterns of SOHIC tested specimen by multiple Gaussian peak-fitting method estimated about 68% increment in micro-deformation and approximately 170% increase in dislocation density.

Investigation of Stress-Oriented Hydrogen-Induced Cracking (SOHIC) in an Amine Absorber Column of an Oil Refinery

Stress-oriented hydrogen-induced cracking (SOHIC) of an amine absorber column made of a Hydrogen Induced Cracking (HIC) resistant steel and operating under wet H2S service was investigated. SOHIC was not related to welds in the column and evolved in two steps: initiation of HIC cracks in the rolling plane and through-thickness linking of the HIC cracks. Both the original HIC cracks as well as the linking cracks propagated with a cleavage mechanism. The key factors identified were periods with high hydrogen charging conditions, manifested by high H2S/amine ratio, and stress triaxiality, imposed by the relatively large thickness of the plate. In addition, the mechanical properties of the steel away from cracked regions were unaffected, indicating the localized nature of SOHIC.

Stress corrosion cracking of L360NS pipeline steel in sulfur environment

Slow strain rate test (SSRT) and tensile fracture observation are applied to study the stress corrosion cracking (SCC) of L360NS pipeline steel. 5.0 wt. % sodium chloride solution containing elemental sulfur and 0.5 wt. % glacial acetic acid solution containing elemental sulfur are used. The results show that brittle fracture mainly occurs on the samples in high sulfur environment. In the sulfur suspension solution, the SCC sensitivity of L360NS pipeline steel increases along elemental sulfur content. In sulfur melting cladding condition, obvious corrosion can be observed with a large amount of corrosion pits appearing on the gauge section of the sample. The corrosion products are Fe1+xS, black easily detached, and H2. In sulfur suspension and sulfur melting cladding conditions, stress oriented hydrogen induced cracking (SOHIC) is the main cracking, which is caused by the joint effect of SCC and hydrogen induced cracking (HIC).

Acoustic Emission Monitoring of Wet H2S Cracking of Linepipe Steels: Application to Hydrogen-Induced Cracking and Stress-Oriented Hydrogen-Induced Cracking

Abstract Acoustic emission (AE) was used for monitoring steel cracking during exposure to wet hydrogen sulfide (H2S) environments. A method for filtering AE data related to hydrogen-induced cracking (HIC) was presented and applied for several case studies. In a series of tests on unstressed sweet service steels, evolution of AE indicated three successive HIC phases. An initial incubation period corresponded to hydrogen entry in the steel, during which no cracking occurred. Then two cracking phases were detected. The first was associated with decohesion of weak steel interphases. The second was identified as crack propagation under high internal hydrogen pressure. Crack propagation decreased and eventually ceased over time. Analysis of AE data was then used to evaluate the extent of HIC after sour exposure. Correlation was found when appropriate data filtering was applied. AE analysis was also applied to sour service steels under an applied load. The first steel exhibited HIC AE signals. Its fracture surfa...

Failures by SOHIC in Sour Hydrocarbon Service

This article discusses two failures experienced in spiral-welded pipeline/piping due to stress-oriented hydrogen-induced cracking (SOHIC). The first identified SOHIC failure occurred in 1974, before the term SOHIC was coined. A second failure occurred in 1998 in the piping system handling aggressive sour natural gas liquid (NGL) service. The conditions leading to SOHIC failures and differences between the two failures are discussed. The influence of these failures on company standards is covered.

THE SINGLE EFFECT OF MICROBE ON THE CORROSION BEHAVIORS OF 25 STEEL IN SEAWATER

Biological elements have a significant impact on lifetime prediction of marine carbon steel facilities.Microbe can produce pitting,crevice corrosion,selective dealloying and stress-oriented hydrogen-induced cracking,which accelerate both localized and average corrosion rates of carbon steel. The formation of microbe films can also reduce the corrosion rate of 25 steel through inhibition of oxygen diffusion and depletion of oxygen in the electrolyte and metal/solution interface.The research on the single effect of microbe on the corrosion behaviors of metal is insufficient up to now.In this work,the single effect of microbe on the corrosion behaviors of 25 steel was studied by comparing the corrosion behaviors of the carbon steel in natural seawater and in sterile seawater.The results show that in most of immerging periods,the bacterial activity at the interface accelerated the average corrosion rate of 25 steel.When the corrosion time was 365 d,the average corrosion rate of 25 steel immersed in natural seawater was 2.6 times that in sterile seawater.However,when the corrosion time was 28 d,the biofilms inhibited the corrosion of 25 steel.The species and contents of microbes significantly influenced the corrosion behavior of 25 steel.The microbes in the corrosion product mainly consisted of pseudomonas,vibrio,crenothrixandleptothrix,thiobacillus and sulfate-reducing bacteria.When the corrosion time was 365 d,flavobacterium also existed in the corrosion product.The contents of aerobe,facultative anaerobe and anaerobe reached the maximum value when the corrosion time was 28,91 and 184 d,respectively.The regular change of the contents of microbes with the immerging time led to the different microbe corrosion mechanisms of 25 steel.

STRESS ORIENTED HYDROGEN INDUCED CRACKING BEHAVIOR OF HEAT AFFECTED ZONE OF L360MCS STEEL IN WET H<SUB>2</SUB>S ENVIRONMENT

Stress oriented hydrogen induced cracking (SOHIC) behavior of heat affected zone (HAZ) of L360MCS steel in wet H2S environment was studied by separating crack, SEM and EDS. The cracks are formed by four-point bending test in wet H2S environment. The microstructure of HAZ is obviously different from the base metal, and the hardness of HAZ is lower than those of the base metal and welding joint. The fracture surface of the cracks was separated and the hy- drogen blisters were torn off. The cross section and fracture surface of the cracks are analyzed by SEM and EDS. Results show that the cracks of SOHIC appeared as axial crack and vertical crack, and the former is preferential. The appearance of cracks is associated with the low hardness value of HAZ. The dimension of hydrogen blasters in tension stress zone of bended specimen is bigger than that in unstressed specimen, which is due to hydrogen concentration in bended specimen is higher. Both axial and vertical cracks nucleate independently and propagate in the quasi-cleavage manner. Tension stress not only increases the supersaturated hydrogen concentration in tension stress zone but directly promotes vertical crack propagation. Axial crack nucleates at MnS, CaS and precipitated phase, and propagates under internal hydrogen pressure. Vertical crack mainly nu- cleates on precipitated phase and propagates under both internal hydrogen pressure and tensile stress.

CARELSO 70 SOHIC

Abstract CarElso 70 SOHIC is a steel alloy with special melt practice producing a pressure vessel material with excellent resistance to stress-oriented hydrogen-induced cracking (SOHIC). This datasheet provides information on composition, hardness, and tensile properties as well as fracture toughness. It also includes information on high temperature performance and corrosion resistance as well as forming and joining. Filing Code: SA-590. Producer or source: Industeel USA, LLC.

Study on the Electrochemical Behavior of the Weldment for SPV50Q Steel in H<sub>2</sub>S-Containing Environment

The difference in microstructures of the base metal (BM), weld metal (WM) and heat-affected zone (HAZ) in the weldment is one of the major reasons for the failure of the welded equipments, which can be essentially attributed to the non-homogeneous corrosion occurred electrochemically on the weldment. Therefore, it is necessary to explore the corrosion properties of weldment. In this paper, the electrochemical behavior of SPV50Q steel weldment was investigated. The polarization curves of BM, WM and HAZ in 5wt.%NaCl-0.5wt.%HAc solution containing H2S were measured by potentiodynamic polarization. Interface characterization was also conducted by electrochemical impedance spectroscopy (EIS). The results show the anodic curves are almost same regardless of various pH or H2S content, but the cathodic curves show some difference. Relatively large variation in corrosion current density (icorr) obtained by fitting technique exists among BM, WM and HAZ. icorr of WM and HAZ is larger than that of BM, and icorr of WM is maximum. According to EIS results, polarization resistance (Rp) increases in the orders of WM, HAZ and BM. It is concluded that WM and HAZ are less resistant to corrosion than BM, which can be correlated to the premature failure of the weldment serviced in H2S-containing environment such as sulfide stress corrosion cracking (SSCC) and /or stress oriented hydrogen-induced cracking (SOHIC) etc.

Failure analysis of a crude oil pipeline

The transversal cracking of a seamed API 5L X46 steel tube belonging to a crude oil pipeline was investigated. The main cracking nucleated in the internal surface of the tube, at the boundary between the heat-affected zone (HAZ) and the weld metal, propagating in a stable mode along the radial and longitudinal directions. Stress raisers, such as welding defects and corrosion pits, were associated to the cracking nucleation. The internal surface of the tube and the cracking surfaces presented a deposit layer, which was rich in Fe, O and S. Diffractometry on the internal identified the presence of a multi-layered corrosion deposit, formed by iron oxide (Fe 2O 3 and Fe 3O 4) and iron sulphides, such as pyrrhotite, mackinawite and pyrite, indicating the action of a H 2S corrosion assisted mechanism. The crack propagation path did not depend on the welding macrostructure, growing perpendicular to both the internal surface and main tensile stresses. Crack propagation was, however, microstructure sensitive, with a more intense branching occurring inside the base metal rather than the HAZ region. Both regions presented cracking (blistering) of the sulphide/matrix interface and microfractographic examination indicated the action of a ductile fracture mechanism linking the H 2 blisters, reinforcing the idea that atomic hydrogen association rather than hydrogen embrittlement was the active mechanism during the cracking of the pipeline. These observations indicated that failure of the pipeline occurred by a stress-oriented hydrogen-induced cracking (SOHIC) mechanism.

Evaluation of Cracking Behavior of SPV50Q High Strength Steel Weldment in Wet H<sub>2</sub>S Containing Environment

JIS-SPV50Q high strength steel is often employed in construction of liquid petroleum gas (LPG) spherical tanks due to its high strength and good ductility. In general, post weld heat treatment is not performed after welding of SPV50Q high strength steel and welding residual stress will be retained in weldment. Service experience and inspection indicate that higher H2S concentration and welding residual stress result in the environmental failure, such as blistering or hydrogen induced cracking (HIC), sulfide stress corrosion cracking (SSCC) and stress oriented hydrogen induced cracking (SOHIC). In the present paper, the cracking behavior of SPV50Q high strength steel weldment by manual electric arc welding has been investigated in various saturate solutions with different concentrations of H2S. The results of slow strain rate testing, performed at a strain of 1×10-6s-1, reveal the presence of SSCC and HIC in the base metal adjacent to HAZ. The ffects of the different temperatures of post weld heat treatment on cracking are discussed. The suitable post weld heat treatment could increase the resistance of SPV50Q weldment on SSCC or HIC and does not decrease the mechanical properties of SPV50Q weldment.

Relationship Between Corrosion and the Biological Sulfur Cycle: A Review

Abstract Sulfur and sulfur compounds can produce pitting, crevice corrosion, dealloying, stress corrosion cracking, and stress-oriented hydrogen-induced cracking of susceptible metals and alloys. Even though the metabolic by-products of the biological sulfur cycle are extremely corrosive, there are no correlations between numbers and types of sulfur-related organisms and the probability or rate of corrosion. Determination of specific mechanisms for corrosion caused by microbiologically mediated oxidation and reduction of sulfur and sulfur compounds is complicated by the variety of potential metabolic/energy sources and by-products; the coexistence of reduced and oxidized sulfur species; competing reactions with inorganic and organic compounds; and the versatility and adaptability of microorganisms in biofilms. The microbial ecology of sulfur-rich environments is poorly understood because of the association of aerobes and anaerobes and the mutualism or succession of heterotrophs to autotrophs. The physical...

Susceptibility of Conventional Pressure Vessel Steel to Hydrogen-Induced Cracking and Stress-Oriented Hydrogen-Induced Cracking in Hydrogen Sulfide-Containing Diglycolamine Solutions

Abstract Hydrogen-induced cracking (HIC) and stress-oriented hydrogen-induced cracking (SOHIC) tests were conducted on a conventional type A516-70 (UNS K02700) pressure vessel steel exposed to hydr...

Large-Scale Wet Hydrogen Sulfide Cracking Performance: Evaluation of Metallurgical, Mechanical, and Welding Variables

Abstract The serviceability of welded steel equipment in wet hydrogen sulfide (H2S) service was studied. Large-scale exposure tests were conducted using a steel pressure vessel containing various welded test plates. Effects of variables including steel base plate composition, metallurgical processing, welding, applied stress, and orientation were examined. Particular attention was given to large-scale behavior vs behavior for small-scale laboratory test specimens under an applied tensile stress; performance of conventional carbon steels (CS) vs advanced CS designed for enhanced resistance to hydrogen-induced cracking (HIC); and the interrelationship of stress, welding, and plate orientation on susceptibility to wet H2S cracking. Results provided insight on the role of steel quality and microstructure in susceptibility of CS to HIC, stress-oriented hydrogen-induced cracking (SOHIC), and sulfide stress cracking (SSC).