API 5L X65 Research Articles

A New Approach to Simulate HSLA Steel Multipass Welding through Distributed Point Heat Sources Model

Mechanical properties of welded joints depend on the way heat flows through the welding passes. In multipass welding the reheating of the heat affected zone (HAZ) can form local brittle zones that need to be delimited for evaluation. The difficulty lies in the choice of a model that can simulate multipass welding. This study evaluated Rosenthal’s Medium Thick Plate (MTP) and the Distributed heat Sources (DHS) of Mhyr and Gröng models. Two assumptions were considered for both models: constant and temperature-dependent physical properties. It was carried out on a multipass welding of an API 5L X80 tube, with 1016 mm (42″) external diameter, 16 mm thick and half V-groove bevel, in the 3G up position. The root pass was welded with Gas Metal Arc Welding (GMAW) process with controlled short-circuit transfer. The Flux Cored Arc Welding (FCAW) process was used in the filling and finishing passes, using filler metal E111T1-K3M-JH4. The evaluation criteria used were overlapping the simulated isotherms on the marks revealed in the macrographs and the comparison between the experimental thermal cycle and those simulated by the proposed models. The DHS model with the temperature-dependent properties presented the best results and simulated with accuracy the HAZ of root and second welding passes. In this way, it was possible to delimit the HAZ heated sub-regions.

Correction to: Efficiency of Green Inhibitors Against Hydrogen Embrittlement on Mechanical Properties of Pipe Steel API 5L X52 in Hydrochloric Acid Medium

Correction to: Efficiency of Green Inhibitors Against Hydrogen Embrittlement on Mechanical Properties of Pipe Steel API 5L X52 in Hydrochloric Acid Medium

Analysis Cracking Corrosion on Carbon Steel Pipes API 5L-X65 In Solution 7700 ml Aquades, 250 ml Acetic Acid and 50 ml Ammonia with Gas CO2 and H2S in Saturation Condition

The oil and gas industry exploration that will generally be followed by corrosive substances including sweet gas (eg H2S and CO2), it will result in corrosion event. The corrosion stress cracking will cause the carbon steel pipe to break so that production oil and gas can be stopped. The research aims in this paper is to analyze the corrosion event of carbon steel pipe in laboratory scale on acid environment with the existence of sweet gas H2O and CO2 by using three points loading method. This research uses carbon steel pipe API 5L-X65 which stay in condensation environment of 7700 ml aquades, 250 ml acetic acid and 50 ml ammonia, then filled sweet gas CO2 and H2S in saturated state. Based on the test results of microstructure and microscope polarized, there is a phenomenon corrosion stress cracking, i.e transgranular stress cracking corrosion and intergranular stress cracking corrosion. The accelerate corrosion that happened at the test sample will be greater if ever greater given deflection for the time of the same presentation. Crack deepness in the test of the test sample will deeper if ever greater given deflection. The cracks in the sample test will deeper if it was given stress σ greater for the same exposure time.

Corrosion Resistances of Steel Pipe Coated with Two Types of Enamel by Two Coating Processes

The corrosion behaviors of uncoated, enamel-coated, and epoxy-coated steel samples were evaluated in 3.5 wt.% NaCl solution with open-circuit potential, electrochemical impedance spectroscopy and potentiodynamic polarization tests. Two types of enamel (powder and slurry) were coated on steel samples in electrostatic and wet spraying processes, respectively. Twelve 25 mm × 25 mm steel samples were cut from an API 5L X65 pipe of 323.850 mm in outer diameter and 9.525 mm in wall thickness. They were divided into four groups of three identical samples. Each group represents one of the four conditions: uncoated, powder enamel-coated, slurry enamel-coated and epoxy-coated. Scanning electron microscopy images revealed that the powder and slurry enamel coatings were approximately 180 and 235 µm thick, respectively. The powder enamel coating has fewer but larger isolated pores than the slurry enamel coating. Electrochemical tests consistently indicated that the powder and slurry enamel coatings provided slightly better and worse corrosion protection to the coated steel samples, respectively, than the epoxy coating. The charge transfer resistances of all the coated samples are approximately 108 times larger than that of the uncoated samples. All the coated samples were unlikely corroded within 2 h of immersion.

Fracture-Toughness and Fatigue Crack Growth Evaluation in the Transversal Direction of the Longitudinal Weld of an API X52 Steel Pipeline

Abstract In this paper, the fracture-toughness and fatigue crack growth rates of the deposited seam weld on the longitudinal pipeline API 5L X52 were evaluated. The study was performed with nonstandard curved specimens, which were machined in the transversal direction of the seam weld with a crack-initiating notch aligned perpendicular to the direction of the deposited seam weld metal. The fractographic analysis showed that the low fracture-toughness of the weld can be attributed to the the existence of elements capable of nucleating brittle fracture and the fact that the intrinsic porosity in the transversal direction provided a favorable crack path for separating the fracture plane, resulting in low fracture-toughness values. Finally, the resistance decrease with respect to the fatigue crack growth was attributed to the small grain size because of the effect of roughness-induced crack closure as well as the interaction of the crack and the inherent porosity.

Microstructural Characterization and Mechanical Properties of TIG-Welded API 5L X60 HSLA Steel and AISI 310S Stainless Steel Dissimilar Joints

Dissimilar joining of API 5L X60 ferritic HSLA steel and AISI 310S austenitic stainless steel was conducted by tungsten inert gas (TIG) welding process using ERNiCr-3, ER310, ER2209, and ER309L filler metals. Microstructural characteristics and mechanical properties of the weldments were studied using optical and scanning electron microscopy, ferritometry, microhardness, tensile, and impact tests. The microstructure investigations revealed macro-segregation occurrence and formation of Type II boundaries at the interface of welds with API 5L X60 steel. In tension tests, the joints prepared by ER2209 filler metal showed the maximum yield and ultimate tensile strength values, and the failures were always obtained at the side of API 5L X60. The results of Charpy impact tests indicated that the maximum fracture energy is related to the weld made by ER2209 filler metal. At last, it was concluded that for the dissimilar welding between API 5L X60 and AISI 310S, the weld metal prepared by ER2209 duplex stainless steel filler metal offers the optimum properties at room temperature.

Corrosion Evaluation of Pipeline Steel API 5L X52 in partially deaerated Produced Water with High Chloride Content

Corrosion Evaluation of Pipeline Steel API 5L X52 in partially deaerated Produced Water with High Chloride Content

Synergistic effect of halide ions and gum arabic for the corrosion inhibition of API5L X70 pipeline steel in H2SO4

This paper aims to increase the inhibition efficiency of gum arabic (GA) for the corrosion of API5L X70 pipeline steel in sulfuric acid through the addition of halide ions (potassium iodide [KI], potassium chloride [KCl], and potassium bromide [KBr]). The synergistic effect of GA and halide ions has been studied using potentiodynamic polarization curves, electrochemical impedance spectroscopy, and surface analysis by scanning electron microscope (SEM). The results show that substantial corrosion inhibition (99%) using 2 g L−1 GA and 0.5 mM KI can be obtained in synergistic manner. The adsorption of GA in combination with iodide ions follows Langmuir adsorption isotherm. GA combined with KI acts as a mixed‐type inhibitor in sulfuric acid.

Production and Corrosion Resistance of Thermally Sprayed Fe-Based Amorphous Coatings from Mechanically Milled Feedstock Powders

Mechanically milled FeCrNbB feedstock powders from commercial precursors were used to produce amorphous coatings through two different industrial thermal-spraying techniques: high-velocity oxygen fuel (HVOF) and flame spraying. Microstructure, thermal behavior, and hardness of the coatings and their corrosion resistances in acidic and alkaline chloride-rich media were comparatively studied. HVOF process was effective to produce ~ 200-µm-thick highly amorphous coatings with hardness over than 700 HV0.3 and low porosity (~ 5 pct). Flame-sprayed ~ 220-µm-thick coatings were nanocrystalline, composed of α-Fe, Fe2B, FeNbB, and Fe2O3 phases and presented hardness of 564 HV0.3 and ~ 10 pct porosity. Electrochemical measurements indicated that HVOF coatings exhibit higher corrosion resistance than flame-sprayed ones thanks to the higher amorphous content and lower porosity resulting from the former processing route. Electrochemical impedance spectroscopy results demonstrated that amorphous HVOF Fe60Cr8Nb8B24 (at. pct) coatings are interesting to protect mild steels such as the API 5L X80 against corrosion in chloride-rich environments.

Evaluation of chitosan and carboxymethyl cellulose as ecofriendly corrosion inhibitors for steel

The study was aimed at establishing the possibility of using eco-friendly natural polymers to formulate corrosion inhibitors for sweet oil field environment. Against this background, the performance of two natural polymers; chitosan and carboxymethyl cellulose (CMC) as single component corrosion inhibitors in comparison with a commercial inhibitor formulations, on API 5L X60 pipeline steel in CO2 saturated 3.5% NaCl solution were investigated using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) techniques; complemented with surface morphology characterization of the corroded steel samples without and with inhibitors using scanning electron microscope (SEM). The results indicate that there is a remarkable difference in inhibition efficiency of each inhibitor on the API 5L X60 steel and the commercial inhibitor formulations. Inhibition efficiency increased with the increase of inhibitors' concentrations. Immersion time was found to have a profound effect on the corrosion inhibition performance of all the inhibitors. Also the inhibition efficiency was found to decrease with the increase in temperature. Potentiodynamic polarization results reveal a mixed-type inhibition for all inhibitors. The adsorption of each inhibitor on the steel surface obeys Langmuir's isotherm.

Experimental and numerical investigation of the strain response of a dented API 5L X52 pipeline subjected to continuously increasing internal pressure

A dent is a common type of defect that occurs during pipeline service. A dented region on a pipe usually creates a strong stress concentration that may become a threat to the safety and integrity of the pipeline. Therefore, such issues are major concerns for pipeline managers. To investigate the strain history behaviour of a dented steel pipeline subjected to increasing internal pressure, a full-scale experimental burst test was performed, and a nonlinear finite element method was used to compare the numerical and experimental results in this study. The paper first discusses the test specimens and test results. Then, the finite element numerical results are verified using the experimental measurement results. Subsequently, the strain behaviour at measurement points and the deformation behaviour of the test pipes were analysed in detail. Furthermore, a sensitivity analysis of strain in the axial and circumferential directions from the dent centre was performed. Deformation analysis reveal that an outward convex phenomenon occurred in axial shoulders on both sides of the dent when the Pipewall Yield Pressure reached. Test results and finite element analysis show that the strain in the dented regions changes rapidly and sharply with a large range, which can easily lead to fatigue under operation pressure for an unconstrained dent.

Allium sativum (garlic extract) as a green corrosion inhibitor with biocidal properties for the control of MIC in carbon steel and stainless steel in oilfield environments

In the present study, the effectiveness of garlic extract to inhibit the bio-corrosion of carbon steel API 5LX (CS) and stainless steel 316 (SS) in the presence of Bacillus subtilis A1 and Streptomyces parvus B7 was estimated. The antibacterial activity of the garlic extract (GAE) was tested; 100 ppm of the GAE was identified as the minimal inhibitory concentration for bacterial growth. Weight loss and electrochemical studies including linear polarization and AC impedance along with surface analysis were used to examine the corrosion inhibition efficiency (IE) for both metals in the presence of GAE. The strains A1, B7 and their mixed consortium caused severe corrosion to both metals. In the presence of GAE the IE for abiotic system was about 81 ± 3% and 75 ± 3%, while in the presence of the mixed consortium the IE was 72 ± 3% and 69 ± 3% for CS and SS, respectively. Gas chromatography mass spectrum analysis of GAE indicated that GAE contains a sulphur rich compound which plays a key role in the inhibition of both bacterial development and corrosion. This is the first time garlic extract is proposed as a green corrosion inhibitor with biocidal activity to control biocorrosion in hypersaline corrosive environment containing microorganisms.

Reduction of hydrogen embrittlement of API 5l X65 steel pipe using a green inhibitor

Several inhibitors are used in industry to reduce the corrosive effects of harsh environments on the mechanical properties of steel structures. More recently, eco-friendly (green) inhibitors are being developed to replace the synthetic ones which are known to possess toxic organic molecules. In the present study, Ruta Chalepensis (Fijil) green corrosion inhibitors are utilized with API 5L X65 pipe steel to study their effectiveness in reducing the corrosive effects of HCl acid. Notched specimens are immersed in HCl and HCl with different concentrations of Fijil (3, 5, 10 and 30 vol%), at room temperature and at 80 °C, for periods of 3, 7 and 10 days. Charpy tests are carried out, after each period, on treated (maked in the HCl media with green inhibitor for different concentration) and untreated standard specimens to evaluate the response of the material under dynamic loading. The load-displacement curves are found to consist of four zones corresponding to different crack advance events. The optimum concentration of green inhibitor is found to be 5 vol%. Immersion of API 5L X65 in HCl with 5% green inhibitor is seen to reduce the acid's effect. The improvement of the material's fracture toughness due to the inhibitor was more than 40%.

Efficiency of Green Inhibitors Against Hydrogen Embrittlement on Mechanical Properties of Pipe Steel API 5L X52 in Hydrochloric Acid Medium

The impact of environment can cause many types of degradations such as pitting corrosion, stress corrosion cracking and sulphide stress cracking of metal structures. One of the serious problems of oil extracting industry is the corrosion process. Recently, there were a number of resource failures caused by internal corrosion phenomena recorded in oil and gas industry; the reports confirmed that the failures were due to the effect of traces amounts of Hydrochloric acid. The objective of this study is to use the plant extracts as corrosion inhibitors for API 5L X52 steel. Indeed, these natural extracts contain many families of natural organic compounds “Green”, readily available and renewable. The conducted mechanics tests in this study in the presence of green inhibitors of plant origin will give very promising results on the fracture mechanics properties. The importance of this area of research is to be attributed to the fact that natural products can replace the currently used toxic organic molecules that are condemned by the world directives for using environmentally unacceptable inhibitors.

Fatigue behaviour of corrosion pits in X65 steel pipelines

Corrosion pits are a form of geometrical discontinuity that lead to stress and strain concentration in engineering components, resulting in crack initiation under service loading conditions and ultimately fracture and failure. Initiation and propagation of cracks in offshore pipelines can lead to loss of containment and environmental and commercial impacts. In order to prevent such failures, tools to predict the structural integrity of pipelines need to be improved. This work investigates the fatigue behaviour of corrosion pits in API-5L X65 grade steel pipeline utilising numerical and analytical methods. Firstly, load-controlled fatigue tests were carried out on smooth X65 steel samples to establish S–N data. Secondly, local stress–strain behaviour at corrosion pits and its effect on fatigue crack initiation were investigated using elastic-plastic finite element analysis of samples containing a single corrosion pit under cyclic loading. Analysis of stabilised stress–strain hysteresis loops at corrosion pits showed that the local stress ratio at the pit changes from 0.1 to −0.4 while the applied stress amplitude increases with the same stress ratio of 0.1. Analytical methods were also used to predict the local maximum stress and strain at the pit, which showed a similar local stress ratio to the finite element analysis result but lower stress and strain ranges. Finally, fatigue crack initiation life was predicted using the combination of finite element stress and strain analysis and the Smith–Watson–Topper strain–life approach. An advantage of this method for life estimation is that this approach considers the local stress and strains at corrosion pits rather than applied stress.

Multifactorial study of erosion–corrosion wear of a X65 steel by slurry of simulated copper tailing

Abstract A multifactorial study of erosion–corrosion (E–C) is carried out to quantify the effects of velocity, particle concentration, temperature, pH, dissolved oxygen, and copper ion content, with respect to the transport of tailings slurry through an API 5L X65 pipe. The experimental design is implemented using a rotating cylinder electrode and evaluating the resulting E–C damage by weight loss. An analysis of the statistical significance reveals that the variation in the wear rate is explained by three main effects (velocity, oxygen, and temperature) and two interactions (velocity/oxygen and particle/copper content). An empirical equation is formulated to produce contour maps of the main interactions. It is concluded that the primary damage mechanisms are the deposition of corrosion products consecutively disturbed by impinging particles and localized plastic deformation.

Relationship between Pipeline Wall Thickness (Gr. X60) and Water Depth towards Avoiding Failure during Installation

Oil and gas today being developed at different water depth characterized as shallow, deep and ultra-deep waters. Among the major components involved during the offshore installation is pipelines. Pipelines are a transportation method of material through a pipe. In oil and gas industry, pipeline come from a bunch of line pipe that welded together to become a long pipeline and can be divided into two which is gas pipeline and oil pipeline. In order to perform pipeline installation, we need pipe laying barge or pipe laying vessel. However, pipe laying vessel can be divided into two types: S-lay vessel and J-lay vessel. The function of pipe lay vessel is not only to perform pipeline installation. It also performed installation of umbilical or electrical cables. In the simple words, pipe lay vessel is performing the installation of subsea in all the connecting infrastructures. Besides that, the installation processes of pipelines require special focus to make the installation succeed. For instance, the heavy pipelines may exceed the lay vessel’s tension capacities in certain kind of water depth. Pipeline have their own characteristic and we can group it or differentiate it by certain parameters such as grade of material, type of material, size of diameter, size of wall thickness and the strength. For instances, wall thickness parameter studies indicate that if use the higher steel grade of the pipelines will have a significant contribution in pipeline wall thickness reduction. When running the process of pipe lay, water depth is the most critical thing that we need to monitor and concern about because of course we cannot control the water depth but we can control the characteristic of the pipe like apply line pipe that have wall thickness suitable with current water depth in order to avoid failure during the installation. This research will analyse whether the pipeline parameter meet the requirements limit and minimum yield stress. It will overlook to simulate pipe grade API 5L X60 which size from 8 to 20mm thickness with a water depth of 50 to 300m. Result shown that pipeline installation will fail from the wall thickness of 18mm onwards since it has been passed the critical yield percentage.

Effect of silicate-based films on the corrosion behavior of the API 5L X80 pipeline steel

The aim of this work was to investigate the effect of silicate-based films on the corrosion resistance of the API 5L X80 steel in carbonate-bicarbonate solution at room temperature. The films were electrochemically obtained by anodic and cathodic treatments and by immersion in 1.0 M sodium metasilicate solution. The corrosion behavior was evaluated using electrochemical impedance spectroscopy and potentiodynamic polarization. Film morphology was examined by scanning electron microscopy. Adhesion strength was measured by pull-off tests. The chemical composition was evaluated by X-ray photoelectron spectroscopy. The anodic film yielded the best corrosion resistance (protection efficiency 83%). The protection mechanism is discussed.

Effect of L-Citrulline from Watermelon Seed Extract as a Green Corrosion Inhibitor against the Corrosion Rate of Pipe Steel API 5L X65

API 5L X65 carbon steel is used in many industries, especially as oil and gas pipelines. However, this carbon steel pipe is vulnerable to corrosion at the inner surface owing to the flow of oil that is a multiphase system and contains dissolved salts. The corrosion phenomenon of the internal surface can be prevented by using an inhibitor. Most of the inhibitors used in industry are composed of compounds that are toxic and environmentally unfriendly. Consequently, the use of a natural inhibitor is at the forefront of corrosion inhibition studies. This study examines the efficiency of watermelon seed extract as an inhibitor before and after the addition of methyl ethyl glycol (MEG). The influence of L-citrulline from watermelon seed extract (WMSE) and MEG on the inhibition of corrosion of carbon steel in 3% NaCl containing acetic acid saturated by CO2 at room temperature was investigated by the immersion test, polarization test, electrochemical impedance spectroscopy (EIS), and surface analysis by scanning electron microscopy (SEM). According to the experiment results, the corrosion rate increased with the acid concentration and the effect of CO2. The corrosion rate can be inhibited by MEG, WMSE, and mixtures thereof. In comparison with 3% NaCl media containing acetic acid (HAc) 3360 ppm in saturated CO2 at room temperature, the inhibition efficiency of WMSE using polarization and EIS methods were 93.54% and 95.89%, respectively. However, based on the immersion test results, the inhibition efficiency was decreased. The inhibition efficiency of WMSE dropped after 120 hours of the immersion process by almost 40fold to 2.38%, while the efficiency of MEG was able to inhibit the surface by 80.48%. The mechanism of the inhibition by a WMSE molecule is through a chemisorption process, which forms a complex bond and generates a passive layer of Fe-WMSE Keyword: citrulline, corrosion, electrochemical

Biofilm Formation and Corrosion on Carbon Steel API 5LX60 in Clayey Soil

Corrosion of buried pipelines is a matter of concern to the oil and gas industry since the time when carbon steel began to be widely used in these pipelines for the transportation of fluids. The microbial communities associated with biofilms promote modification in the surrounding environment and may accentuate the degradation of oil and gas pipelines causing leaks or even accidents. This work aimed to evaluate corrosion and biofilm formation in carbon steel API 5LX60 coupons buried in clayey soil from an industrial region in north-eastern Brazil. The average corrosion rates were determined by gravimetric test and the quantification of bacteria and fungi were using the Most Probable Number (MPN) and Colony Forming Units (CFU) techniques respectively. The results showed a great influence of clayey soil on corrosion rates and time of adherence for microorganisms on metal surfaces.