Pipeline Corrosion Research Articles

A review: the utilization potency of biopolymer as an eco-friendly scale inhibitors

Scale formation is one of the major issues in the petroleum industry. The development of these scale layers could result in production losses and equipment instability because of pipeline blockage, energy leakage, corrosion acceleration and severe accidents which will impact the safety of the production process. The utilization of chemical scale inhibitors (SIs) is considered an economical and successful route for the scale prevention. Two main components of the chemical SIs are phosphonate and polymer. Many of the phosphorous compounds are toxic and very expensive. Besides, portions of the phosphonate compounds are thermally less stable than polymeric scale inhibitors in a harsh environment of high temperature and high pressure (HTHP). This is considered as an issue as a good scale inhibitor should be able to be applied under wide range of temperature and pressure. Therefore, the continuous development in petroleum production imposes the need to develop a novel phosphorus-free scale inhibitor. Meanwhile, polymers have been broadly applied as a scale inhibitor in oil and gas fields because of their enhanced thermal stability and improved environmental compatibility. Polymeric scale inhibitors also show better dispersing efficiency. Today, the biopolymers have pulled in a tremendous consideration from the industry to replace the utilization of synthetic polymer due to their interesting qualities such as their lightness, strong mechanical properties, and appealing functionality. Biopolymers are insensitive toward brine salinity yet are vulnerable to biological degradation. Specifically, these polymers present enormous potential for environmental application because of their biodegradability, chemical adaptability and reactivity, biocompatibility, and nontoxicity. Recently, several new eco-friendly scale inhibitors have been reported in the literature. Hence, this paper provides a review of the utilization of biopolymer as scale inhibitor in the application of oil and gas industry under laboratory approach or field trial application. The types of scales, chemical scale inhibitors (SIs) and biopolymers are likewise reviewed here. The presented work in this paper is expected to enhance the fundamental understanding of scale formation, as well as contribute to the development process of biopolymer scale inhibitors.

Determining Feature Extraction Parameters for Pulsed Eddy Current Sensor: A Minimisation Problem Approach

Pulsed eddy current (PEC) is an electromagnetic non-destructive testing (NDT) technique mainly used to inspect corrosion in pipelines. Like many other NDT techniques, to quantify pipe wall thickness, a signal feature has to be extracted from the PEC response. The authors’ previous work has exploited the linear relationship of the time-derivative feature to propose an in-situ calibration routine. However, to extract the time-derivative feature, two configuration parameters need to be determined prior to feature extraction. To the authors’ knowledge, none of the previous works explores the determining factors of this configuration parameters, where the current technique is still limited to using brute force method or trial-and-error. This paper brings novelty by formulating the aforementioned problem as a minimisation problem, and solving it using a particle swarm optimisation (PSO) algorithm. The obtained results, compared against brute force method, demonstrate the feasibility and performance improvement of using PSO in determining the configuration parameters. The approach thus presented is validated and the results obtained are justified by analysing the underlying physical system theory.

A REVIEW OF OIL SPILL POLLUTION AND AIR QUALITY IN THE NIGER DELTA: CAUSES, EFFECTS AND CONTROL

Oil spill is the term used to describe the leak of crude petroleum into the environment. Though, the natural seeped of crude oil into the environment is inevitable, the rate of anthropogenic leaching of oil into the ecosystem is alarming. It is released intentionally into the environment through bunkery, pipeline vandalism, pipeline sabotage, corrosion of crude oil pipeline, poor maintenance culture of oil facilities, leak from faulty equipment and sometime, from accidental discharge from tankers, vessels, and other logistic process. While the presence of crude oil on surface water, underground water and the terrestrial contaminates and pollutes them, the open combustion with the atmosphere has no economic, health and socio – economic value. The products of this now deadly mixture of chemical compound are feeds to climate change, acid rain and its associated effects on the ecosystem and many health defects in man. Because the impacts of oil spill remain many years after cleanup, the synergy of green innovations and the implementation of the millennium development goal alone will not do the trick, stakeholders should sit and review the fundamental cause of oil seep into the environment and close the gaps identified in this study in other to nip the cause of oil spill in the bud.

Synthesis of novel demulsifier nano-materials and their application in the oil industry

Nanotechnology is a scientific discipline that has a wide range of applications in practically every aspect of modern life, particularly in the fabrication of nanomaterials and nanocomposites. Due to the importance of this sector economically and in terms of energy supply, one of the most important applications of nanomaterials is their large scale use to remove or minimize the hurdles that the oil and gas industry faces. The hydrothermal method was used to prepare novel Rhodium borate nanoparticles, which were made by first obtaining Rhodium oxide from Rhodium acetate, then reacting with boric acid and other cofactors. The efficiency of the process for generating Rhodium borate nanoparticles was extremely high. The efficiency of the process for generating Rhodium borate nanoparticles was extremely high. The validity of the obtained results was confirmed by the diagnostic and estimation procedures utilized in this work (XRD, FT-IR, SEM, and TEM). One of the most critical processes in petroleum processing is demulsification. To avoid issues during oil transportation and handling, oil emulsions must be broken down. Because of the water content and dissolved salts in the aqueous phase of the emulsion, the presence of water in the crude oil is undesirable and can lead to pipeline corrosion and increased transportation costs. The physical and chemical features of crude oil from the Halfaya oil field in southern Iraq, which is known to contain a certain percentage of water, have been investigated. Rhodium borate (Rh2O3. B2O3·H2O) (DF1) nanoparticles were utilized in this work to separate water from crude oil emulsions. Effective aggregates exist in the synthesized Rhodium borate nanoparticles, allowing them to operate as demulsifying agents. The separation of water from the emulsion by the produced rhodium borate (DF1) and the standard demulsifier (RP96BQ) used in the same oil field at constant temperature (60 °C) and with varying concentrations was compared in this study using crude oil samples. A high separation efficiency was obtained for the prepared nano demulsifier with a percentage of up to (84.2%) compared with the standard demulsifier (RP96BQ).

Using Cloud Point Extraction for Preconcentration and Determination of Iron, Lead, and Cadmium in Drinking Water by Flame Atomic Absorption Spectrometry

The determination of heavy metals in drinking water is an important assessment for quality as well as for the detection of pipeline corrosion. The aim of this research was to develop a simple, low cost, and accurate method based on cloud point extraction for the preconcentration and determination of iron, lead, and cadmium by flame atomic absorption spectrometry (FAAS) when the metal concentration in the sample is below the limit of detection without enrichment. By utilizing both 2,4-diamino-6-phenyl-1,3,5-triazine (DPT) and 3-amino-7-dimethylamino-2-methylphenazine (Neutral Red, NR) as chelating agents, and using Triton X-114 as the surfactant, lead, cadmium, and iron were concentrated in water samples prior to determination. The preconcentration was optimized by varying experimental factors, including the temperature, pH, and the concentrations of the chelating agents and surfactant. Using the optimized conditions, this novel procedure allows the determination of these trace elements with a 20-fold reduction in the detection limit with recoveries as high as 99%. The good reproducibility of the results demonstrates that this method was successfully applied to the determination of iron, lead, and cadmium in water samples by FAAS.

Top of line corrosion in gas-condensate pipelines

Low alloyed carbon steel is the only viable material of construction for long pipelines transporting unprocessed gas-condensate. The water that condenses is highly corrosive because it contains dissolved acid gases, i.e., CO2, H2S and organic acids like acetic and formic acid. The high velocity gas also contains droplets of water and condensate, and these will deposit if they hit the steel surface. Monoethylene glycol (MEG) injected to prevent ice and hydrates must be considered when predicting the composition and corrosivity of the aqueous phases in the pipeline. The liquids gathering at the bottom of the pipe have a higher heat capacity than the gas, and the temperature at the top of the pipe will be slightly lower than at the bottom. As the produced fluids cool during the transport from the hot wells to the process plant, water will condense on the cold pipe surface and more at the top than at the bottom. The literature on Top-of-line corrosion (ToLC) has grown steadily since the first reported case in 1960. There are also several prediction models for ToLC. This review is an overview of the main factors that cause ToLC and how these are modelled. Mass transfer from the aqueous phase at the bottom to the top contribute to the condensation. Despite the low MEG to water ratio in the gas due to the difference in vapour pressure, the fraction of MEG in the condensing water may be considerable. The concentration of MEG in the aqueous phase at the top depends on the mass transfer from bottom. The same is the case for organic acids. Liquid droplets entrained in the gas may deposit top of line and contribute to the chemistry of the aqueous phase. Models for ToLC must thus not only predict the composition of the condensing phases but also the mass transfer to be able to estimate the corrosion rate.

The evolution and influence factors of CO2 flooding crude oil defoaming behavior after depressurization

CO2 flooding crude oil may generate abundant foams in oil field separators after depressurization. A large amount of foams occupies most of the space in a separator and spends much time to burst, which, in turn, reduces the separation efficiency of the separator. Moreover, the incomplete gas-liquid separation will cause corrosion in the downstream pipeline, and damage both the pump and the compressor. Based on the self-development crude oil depressurization foaming device and the CO2 flooding crude oil, this paper studies the evolution of foam and analyzes the function mechanism of asphaltene and wax crystal on defoaming and drainage of crude oil quantitatively. The experimental results show a law that the rate of defoaming and drainage increase at the initial stage and then decrease, which is available for different crude oils. So, the paper proposes a kinetics model of the defoaming and drainage based on the three-degree polynomial function innovatively, which not only describes the evolution of foam volume, but also indicates the change of foam drainage rate. Meanwhile, the experiments found that asphaltene promoted the stability of foams by being adsorbed on foam film in the process of liquid drainage. Wax crystal reduced the fluidity of drainage, which decreased the defoaming and discharging rate. But the wax crystal with specific structures reduced the stability of foams. It is significant to explore the foaming and defoaming mechanism of crude oil for providing references for the improvement of separator efficiency and the development of separation technology.

Analysis of acoustic field characteristics to detect internal pipeline corrosion based on ultrasonic full-focus

Seawater pipelines are an important part of ship structures. After a certain period of service, corrosion becomes a serious problem. Ultrasonic corrosion detection has good applicability in seawater pipeline corrosion detection. Aiming at the focusing problem of ultrasonic arrays in pipeline inspection, the sound pressure characteristics and acoustic field directivity in the propagation process were analyzed. A mathematical model of the acoustic field propagation characteristics was established, and the influence of deflection, focusing of the sound beam, and geometric characteristics of the array element on the characteristics of the ultrasonic acoustic field were analyzed through simulation calculations. An ultrasonic array focusing transducer was used to test the corrosion of a Φ168 pipeline. The results show that the number, size, and focal length of the working array significantly affect the focused acoustic field characteristics of the ultrasonic array. The ultrasonic full-focus method can effectively detect local corrosion of pipelines, and the defect detection accuracy has a nonlinear relationship with the number of working array elements and the focal length of the focus. Within a certain range, with an increase in the number of working elements, the overall tendency of the average error of defect detection gradually decreases. With the increase in focal length, the overall tendency of defect detection error first decreases and then increases, and there is a focal length range with the best detection accuracy. In pipeline inspection, the best working parameters can be selected according to the actual size of the pipeline.

Impact of Crude Oil Emulsion on Pipeline Corrosion

The objective of this work is to study the effect of emulsion formation on steel corrosion in a sweet environment in a laboratory scale. Field experience shows that improper sizing of pipelines in the petroleum industry is often caused by a lack of understanding of three-phase flows which are characterized by a gas phase flowing together with a brine-oil liquid phase. The emulsion formation in these systems plays an important role on the corrosion rates of steel pipelines.

Effect of sulfur content in the crude oil to the corrosion behavior of internal surface of API 5L X65 petroleum pipeline steel

This work discussed the corrosion behavior of the internal surface of pipeline steel caused by the composition of petroleum products, particularly crude oil. Internal and external pipeline corrosion is the notable cause of pipeline failure in Malaysia’s oil and gas industry. However, internal corrosion is preferred to be concerned in this work because it involved one of the major corrosive media in the crude oil, such as sulfur content. This project aim is to find the sulfur concentration in the crude oil using Fourier transform infrared spectroscopy and atomic absorption spectroscopy. The corrosion rate, corrosion current and corrosion potential of the API 5L X65 grade carbon steel pipeline in different simulated H2SO4 solution concentrations were carried out using the Tafel extrapolation technique. The corrosion properties of the samples were morphologically measured by means of optical microscope, scanning electron microscope and energy dispersive X-ray analyses. The results showed that the corrosion rate of the pipeline steel significantly increased with the increasing H2SO4 concentrations. The corrosion products formed on the pipeline steel surfaces were mainly composed of iron sulfate, iron sulfide and iron oxide. These findings are crucial to understanding the corrosion behavior caused by the crude oil and should be further investigate with the other possible influence factors such as temperature and petroleum’s flowing velocity.

SEM-EDX and AFM analysis for the surface corrosion morphology structure and roughness on embedded X70 external pipeline in acidic soil (peat) environment

The corrosion of underground pipelines, especially on external surfaces, is generally influenced by soil properties and surrounding environmental conditions. Corrosion of the external oil and gas pipeline could result in a catastrophic incident in the oil refinery sectors due to friable points and corrosion prevention failure, restricting pipeline performance under high-pressure situations. Furthermore, this issue could cause substantial financial costs for the industry, notably in pipeline maintenance. In this study, an investigation was done focusing on the surface morphology change of this external pipeline under a series of exposure times (14, 30 and 60 days) at ambient and acidic peat environments. Organic peat with a pH range of 4.5–5.5 was chosen, as it can potentially induce surface deterioration on this pipeline external surface. SEM images revealed the production of dispersive corroded deposits form and tiny irregular porosity on the surface of X70 steel, while EDX proved the presence of Fe, O, and C elements associated with corrosion products. Meanwhile, AFM measurements verified that the average surface roughness value increased between 0.06 μm and 5.9 µm, indicating an acidic attack by these acidic soil particles leading to the heterogeneous formation with some defects at random positions on this pipeline surface. The intergranular corrosion mainly contributed to this phenomenon along this pipeline and resulted in a progressive induction of non-uniform and pitting corrosion products.

A Double-Layer Epoxy and Polyaniline/Graphene Oxide Composite Coating for Corrosion Protection of Carbon Steel Immersed in Seawater

Offshore pipelines transport the produced hydrocarbon from the upstream production well to the downstream hydrocarbon separation facilities. Offshore oil and gas pipelines are still the safest way of transporting hydrocarbon, as evidenced by significant low failure rates in contrast with highway transportation, railroad, and ships, yet. The failures do occur and often with catastrophic results, especially to the marine eco-system. There are several origins of pipeline failures, but corrosion is the main one. Coatings are always used to control external corrosion of pipelines, in combination with impressed cathodic protection. However, the development of new coatings has always been an ongoing process. Recently, non-conducting epoxy coatings combined with conducting polymers (CPs) have been used to protect metals from corrosion [1]. Epoxy coatings are often used for corrosion prevention because of their exceptional mechanical, barrier and chemical properties [2-4]. CPs coatings have exhibited promising corrosion inhibition performance of metal substrates because they are environmentally stable, eco-friendly, non-toxic, and adhere firmly to the metal surface [5].In the present work, we developed and applied a double-layer coating on carbon steel (CS) to overcome the limitation of polyaniline/graphene oxide (PANI/GO) composites during an extended emersion time in the corrosive environment. We first synthesized polyaniline (PANI) coating incorporating a single-layer-GO directly on the carbon steel substrate by an electrochemical deposition method (inner layer), which was then followed by the application of a second (outer/top) layer of commercial pure neat epoxy resin. The corrosion resistance studies revealed that the two-layer PANI/GO/epoxy coating offered a significantly better long-term protection towards corrosion of the CS surface than the two-layer PANI/epoxy and, especially, than the single-layer epoxy coating.The coatings’ surface morphology was studied by field-emission scanning electron microscopy. The thickness mapping of the coatings was evaluated by a profilometer. The coatings’ surface wettability was also determined. The electrochemical/corrosion measurements were carried out in an aqueous 3.5 wt.% NaCl. Electrochemical impedance spectroscopy (EIS) and Tafel polarization were used to investigate the corrosion resistance of the coated and uncoated samples. CS samples coated with only PANI, or PANI/GO could not be instigated using Tafel and EIS techniques due to the samples’ relatively good electrical conductivity. Before each Tafel and EIS run, the samples were conditioned at open-circuit potential (OCP) for 1 hour. EIS measurements were performed at OCP in the frequency range between 10 mHz and 50 kHz applying a ±10 mV alternating voltage amplitude. Tafel polarization curves were recorded by anodically polarizing the samples from -200 mV to +200 mV vs. OCP at a scan rate of 1 mV s-1. All potentials in this paper are referred to SCE. All the measurements were performed at 22±1oC.Profilometry measurements revealed that the thickness of the PANI and PANI/GO coatings was 4.84±0.12 mm, while the epoxy coating was substantially thicker, 20.6±0.2 mm, and the double layers coating thickness was 24.9±0.14 mm. Our corrosion resistance results indicate the application of the epoxy coating resulted in a corrosion current decrease by almost two orders of magnitude, while the addition of the thin PANI sub-layer contributed to the further reduction by ca. two orders of magnitude. A surprising finding was that incorporating just 0.01 wt.% of GO into the PANI matrix resulted in a significant additional decrease in the corrosion current of almost two orders of magnitude. Long-term measurements (60 days, Figure 1) revealed that the corrosion resistance of the PANI/GO-epoxy coating remained stable. The PANI-epoxy coating started failing after ca. 37 days, while the resistance of the single-layer epoxy coating was substantially lower and decreased first after ca. 4 days of immersion, and then again started decreasing after ca. 19 days of immersion. The sustained high impedance value for the entire immersion time demonstrates excellent barrier performance of the double-layer PANI/GO-epoxy coating.[1] D.W. DeBerry, Journal of the Electrochemical society, 132 (1985) 1022.[2] V. Mišković-Stanković, J. Zotović, Z. Kačarević-Popović, M.D. Maksimović, Electrochimica acta, 44 (1999) 4269-4277.[3] Y. Wei, L. Zhang, W. Ke, Corrosion science, 49 (2007) 287-302.[4] Y.-X. Lan, C.W. Weng, M.M. Ahmed, K.-H. Luo, W.-F. Ji, W.-R. Liu, J.-M. Yeh, Materials Chemistry and Physics, 264 (2021) 124446.[5] S. Kim, T.-H. Le, C.S. Park, G. Park, K.H. Kim, S. Kim, O.S. Kwon, G.T. Lim, H. Yoon, Scientific reports, 7 (2017) 1-9. Figure 1

An Empirical Equation for Failure Pressure Prediction of High Toughness Pipeline with Interacting Corrosion Defects Subjected to Combined Loadings Based on Artificial Neural Network

Conventional pipeline corrosion assessment methods for failure pressure prediction do not account for interacting defects subjected to internal pressure and axial compressive stress. In any case, the failure pressure predictions are conservative. As such, numerical methods are required. This paper proposes an alternative to the computationally expensive numerical methods, specifically an empirical equation based on Finite Element Analysis (FEA). FEA was conducted to generate training data for an ANN after validating the method against full scale burst test results from past research. An ANN with four inputs and one output was developed. The equation was developed based on the weights and biases of an ANN model trained with failure pressure from the FEA of a high toughness pipeline for various defect spacings, defect depths, defect lengths, and axial compressive stresses. The proposed model was validated against actual burst test results for high toughness materials, with a R2 value of 0.99. Extensive parametric study was subsequently conducted to determine the effects of defect spacing, defect length, defect depth, and axial compressive stress on the failure pressure of the pipe. The results of the empirical equation are comparable to the results from numerical methods for the pipes and loadings considered in this study.

Effect of Magnetic Field on the Corrosion of API-5L-X65 Steel Using Electrochemical Methods in a Flow Loop

Limited studies have been conducted on the effect of a magnetic field on the corrosion behavior of steels. Investigating the effect on pipeline material in the oil and gas industries will be beneficial regarding corrosion prediction and control. In this work, the effect of a magnetic field on the corrosion process of API 5L X65 carbon steel was investigated in a well-developed flow loop using potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS). Using permanent magnets and a well-designed corrosion electrode set-up, the corrosion mechanism of API 5L X65 steel was studied at different magnetic orientations and different flow conditions in a NaCl solution. The surface morphology of the corroded samples was studied using a scanning electron microscope, and the micro-morphologies of the corrosion deposits and the surface elemental composition were analyzed. The results show that the presence of a magnetic field increases the corrosion rate of API 5L X65 carbon steel, and that flow velocities and magnetic orientation have a significant influence on the anodic corrosion current. The results of the polarization curves indicate a negative shift in the Tafel curve, leading to an increase in the corrosion rate with the introduction of a magnetic field in the flow system. The results of the EIS show that the charge transfer rate is decreased when a magnetic field is applied. This work provides important direction in terms of the understanding of the combined effect of magnetism and flow on the corrosion in pipelines used in the oil and gas industries.

Analysis on corrosion-induced failure of shale gas gathering pipelines in the southern Sichuan Basin of China

In the shale gas field in southern Sichuan Basin, the corrosion-induced failure has been observed. In this paper, first, the corrosion phenomenon was analyzed. Second, the causes of corrosion were analyzed thoroughly from the aspects of corrosive environment, materials, and corrosion products. Finally, the field water environment was simulated, and the result showed the following: SRB is one of the main causes of corrosion and perforation of shale gas pipelines, bacterial enrichment is the primary reason for local corrosion, and CO2 promotes the formation of bacterial film and accelerates corrosion.

Performance assessment of multi-MFL inspection using feature-based POD

Oil and gas pipelines, which transport large quantities of oil products and natural gas, are subject to pipeline failures caused by corrosion. Magnetic flux leakage (MFL) is one of the most popular non-destructive testing (NDT) techniques for the detection of pipeline corrosion. Since individual MFL is insensitive to the corrosion components that are parallel with its magnetic field, two types of MFL tools with perpendicular magnetic fields are usually employed in one inspection to detect all corrosion defects. This study applies probability of detection (POD) to quantitatively assess the detection capabilities of two individual MFL tools and their combination. Due to the characteristics of MFL inspection, this study proposes the construction of the POD model as a function of two geometric features, namely the volume and the orientation, which have a significant influence on the MFL signal response. Detection results from two MFL tools are integrated using logical OR operation to study the POD of their combination. With the proposed POD model, the minimum criteria that ensure a corrosion defect will be reliably detected by MFL tools are studied in this paper. The validity of the proposed POD model is justified on the data collected from an in-service pipeline.

Field study on the characteristics of scales in damaged multi-material water supply pipelines: Insights into heavy metal and biological stability

Microbial corrosion and heavy metal accumulation in metal water supply pipelines aggravate scale formation and may result in pipeline leakage or bursting events. To better understand the corrosion and corrosion products in the damaged pipes, deposits excavated from three damaged pipes after 22–26 year service periods were analyzed. Using a combination of advanced micro-mineral techniques and 16S rRNA high-throughput sequencing, the micromorphology, chemical composition, and bacterial community were investigated systematically. Unlined pipe wall scales ruptured while lined pipes leaked due to joint scales. Dendrogram correlation results demonstrated that V/As, Al/Pb, and Cr/Mn clusters exhibited co-adsorption and co-precipitation characteristics. FTIR and XRD analysis detected the presence of γ-FeOOH, α-FeOOH in loose scales, and Fe3O4 in rigid scales. Scales were colonized by various corrosion bacteria, with sulfate reducing bacteria and ammonia producing bacteria being dominant in the scales of anticorrosive and non-corrosive pipe, respectively. Tl, Ca, Al, and Pb exhibited an extremely positive correlation with Rhodocyclaceae, Ferritrophicum, Thermodesulfovibrionia, and Clostridiaceae. Al and V presented a potential Hazard Quotient risk to consumers, while Cd was potentially bioavailable in all inner scales. Overall, this study provides valuable information for the effective management and avoidance of corrosion-induced pipeline damage and heavy metal release.

Inhibition of corrosion of mild steel pipeline carrying simulated oil well water by Allium sativum (garlic) extract

Inhibition of corrosion of mild steel pipeline carrying simulated oil well water by Allium sativum (garlic) extract

The effect of laser energy density on the geometric characteristics, microstructure and corrosion resistance of Co-based coatings by laser cladding

In view of the urgent problem of oil pipeline corrosion in the petroleum industry, Co-based coating was prepared on 42CrMo pipeline steel through laser cladding technology to realize the surface strengthening. The objective of the paper is to investigate the effects of process parameters (Led = 64–100 J/mm2) on the geometric characteristics, microstructure and corrosion resistance of the coating. It can be seen from the results that the increase of Led led to the increase of the dilution ratio and the Marangoni convection effect. At the Led of 90 J/mm2, the grain size of the coating was refined, and the dendrite growth direction was clearly visible. In the electrochemical test, the corrosion resistance of the coating first increased and then decreased with the increase of Led. Using the appropriate process parameters, the corrosion current density of the coating was only 1.740 × 10−7 (A/cm2), and a dense passive film was formed on the Co-based coatings. The Led was closely related to the properties of the coating. While at the Led of 64 J/mm2, the passive film resistance reached 6.474e+003 Ω cm2, and many microcracks appeared on the surface of the coating after corrosion. However, at the Led of 90 J/mm2, the corrosion products on the coating surface were less with excellent corrosion resistance. Therefore, the process parameters of laser cladding showed great effect on the forming quality and corrosion resistance of the coating. The coating with excellent corrosion resistance could be obtained by the adjustment of the process parameters.

Pipeline leak detection and corrosion monitoring based on a novel FBG pipe-fixture sensor

Pipeline leakage and pipeline internal corrosion are two serious threats to pipeline safety operation. In this study, based on the measurement theory of pipeline internal diameter variation and a numerical simulation analysis of existing sensor shortcomings, a novel FBG pipe-fixture sensor is designed and developed to detect pipeline leakage and monitor pipeline internal corrosion simultaneously. A calibration test is conducted, and the test results indicate that the FBG pipe-fixture sensor solves the problem of a large difference between the test values and the theoretical values and eliminates the limitation of measurement range. To validate the actual performance of the sensor, a pipeline leak detection test and a pipeline internal corrosion monitoring test are, respectively, conducted on a steel pipe leak test platform and a steel pipe with different simulated corrosion levels. The test results demonstrate that the FBG pipe-fixture sensor can effectively detect pipe leakage and decrease the localization error of the leakage point to within 1 m. The sensor can also effectively monitor pipe internal corrosion and evaluate the internal corrosion degree with a measurement accuracy of 0.1 mm. The novel FBG pipe-fixture sensor may be a potential sensor for pipeline leak detection and pipeline internal corrosion monitoring.