Pipeline Corrosion Research Articles

Effect of DC grounding electrode currents on the corrosion interference behavior of cathodic protection of nearby pipelines

When operating a direct current (DC) transmission grounding electrode in single-pole return ground mode, transient currents traverse the soil, generating stray currents. These currents can intensify the corrosion of long-distance transmission pipelines near the grounding electrode, subsequently altering the pipeline’s cathodic protection potential. Previous investigations into the interference of grounding electrodes on pipeline cathodic protection have overlooked the cathodic protection systems themselves. Addressing this gap, we integrated COMSOL’s electrochemical module with its AC/DC module. To corroborate the accuracy of our COMSOL-based models, we devised specific validation experiments. Additionally, we crafted a COMSOL application builder interface to streamline computations. Consequently, we derived a multi-regression function to express the cathodic protection potential of the pipeline under varied factors and executed a regression tree classification for soil resistivity. To pinpoint optimal corrosion protection for pipelines, we simulated the cathodic protection of segmentally isolated pipelines, determining that potential excursions can be notably mitigated. This research offers insights into both disturbance evaluation and protective strategies for DC transmission and pipelines.

Sulfone-functionalized metal–organic framework aerogels for selective CO2 capture from natural gas

The accumulation of CO2 in natural gas may reduce the heating value and even pose a risk of corrosion in transport pipelines, making the effective removal of CO2 highly essential. Metal–organic frameworks (MOFs), known for their high specific area and large porosity, show promising application in CO2 capture. However, a major obstacle is their intrinsic fragility and poor physicochemical stability. Herein, we present a sulfone-incorporated in-situ growth and fiber freeze-shaping strategy to develop lightweight, robust, and multiscale porous sulfone-functionalized UiO-67 (UiO-67-SO2) aerogels supported by aramid nanofibers. The resulting UiO-67-SO2 aerogels exhibit remarkable structural features, including a high MOF loading mass (64.39 wt%), low density (5.31 mg/cm3), high specific surface area (769.98 m2g−1), and large porosity (99.24 %). Moreover, owing to the introduction of CO2-philic sulfone groups, the UiO-67-SO2 aerogels exhibit high CO2 adsorption capacity (5.88 mmol/g), a high CO2/CH4 adsorption selectivity (43), and only a 2.77 % decline in their initial CO2 adsorption capacity after 10 cycles. The adsorption energy calculated by density functional theory method further confirms the strong interactions between UiO-67-SO2 aerogels and CO2 molecules. This work presents a promising direction for developing multiscale porous UiO-67-SO2 aerogels for the highly selective removal of CO2 from natural gas.

Preventive and Predictive CNN Based Solution for Pipeline Leak, Blockage and Corrosion Detection

Using Artificial Intelligence (AI) in Internet of Things (IoT) environments has shown great potential to transform many industries. As oil and gas industries continue to push for digital transformation, safety critical applications such as pipeline leak detection, corrosion and blockage detection could also benefit from the adoption of AI and IoT. In our day-to-day life, we come across pipeline accidents and their after-effects. Structural deterioration of pipes in urban distribution network has presented great challenges to the utilities all over the world. When the deterioration exceeds its resiliency, the pipes leak or burst, leading to significant socio-economic overhead. The harsh operating environment, extreme temperature and weather conditions increases the potential for corrosion induced damages to the pipelines. The extreme conditions where the pipelines are located also make it difficult to rely on human operators to physically monitor these pipelines and respond to observed leaks. We propose a preventive and predictive AI-based solution that can continuously monitor the health of a complex pipeline infrastructure. It is a complete solution where pipelines will be scrutinized for blockage, leakage, corrosion, and defects. We propose a novel approach in which video images from IoT cameras installed across various locations on the pipelines are continuously analyzed and a convolutional neural network model is implemented for detecting leaks from the pipeline. Flow sensors will be mounted on the hardware to measure the fluid flow rate. This approach is proposed to deliver greater benefits in terms of accuracy and efficiency.

Probabilistic finite element-based reliability of corroded pipelines with interacting corrosion cluster defects

The random distribution of pitting corrosion defects in pipelines normally leads to interacting cluster defects that behave noticeably different from single metal loss defects. Generally, the probabilistic approaches employ explicit burst pressure limit states for corroded pipelines subjected to only internal pressure. However, a significant level of conservatism is typically associated with the probabilistic assessments of corroded pipelines using the closed-form explicit limit state functions, which presents considerable challenges in maintenance planning and risk management. Therefore, this paper proposes a pathway for developing efficient performance functions for the assessment of interacting pipeline corrosion clustering defects using probabilistic finite element-based reliability method. This seven-stage framework combines multiple uncertainty representation schemes to evaluate the probability of failure. The impact of the critical design variables such as the elastic and plastic material properties, corrosion features, and interacting cluster defect characterisations are identified to guide the burst pressure design, operations and maintenance optimisation. The employed surrogate-based active learning reliability approach yielded an efficient probability estimate at a lesser computational cost than the simulation-based reliability methods. The proposed framework reduces the conservatism and computational cost related with explicit burst pressure limit state functions for corroded pipelines and offers informed decision-making on risk and maintenance management.

Quadruple-branched jellyfish-like demulsifier used for completely demulsifying water-in-oil emulsion at low temperature and its demulsification mechanism

The separation of oil–water emulsions is a pressing and crucial task due to the significant impact on transportation costs and pipeline corrosion. Currently, commercially available demulsifiers mainly utilize ethylene oxide and propylene oxide as raw materials. However, these demulsifiers involve complex and hazardous production processes, exhibit low demulsification efficiency (DE), and require high temperatures exceeding 60 °C. To address these challenges, this study presents a two-step synthesis method for producing a demulsifier (PDB-C6) that resembles a jellyfish. This demulsifier demonstrates a high DE in demulsification processes, operating at lower temperatures and shorter timeframes. Its hydrophilic head can locate water droplets in the emulsions, while the four hydrophobic tails can assist its rapid migration in the oil phase towards the oil–water interface for demulsification. The demulsifying performance was investigated in two W/O emulsions with different oil contents. Bottle tests showed that the DE of PDB-C6 in a 30% oil content W/O emulsion reached 100% with the dosage of 300 mg/L at 40 °C for 2 h, while the dosage of 400 mg/L for 3 h also achieved 100% of DE in a 70% oil content W/O emulsion. In addition, PDB-C6 had excellent demulsification performance in both high salinity and a wide pH range (2–12). Given its low demulsifier amount, low demulsification temperature, short demulsification time and high DE, PDB-C6 shows promise for wide-ranging applications in the petroleum industry. The impacts of PDB-C6 on the oil–water interface were systematically investigated and its possible demulsification mechanism in W/O emulsions was explored in detail. The findings revealed that PDB-C6 had excellent demulsification performance by rapidly migrating to the oil–water interface where it replaced natural surfactant and formed an unstable composite membrane, ultimately reducing the stability of the emulsion and leading to demulsification.

Determination of Heavy Metals and Health Risk Assessment in Tap Water from Wuhan, China, a City with Multiple Drinking Water Sources

The health issues of urban tap water are of great concern in the context of sustainability challenges to the environmental quality of water and the security of the water supply. In this work, tap water from the main urban areas in Wuhan and surface water from the Yangtze River and the Hanjiang River were collected during summer (June) and winter (December), 2022. The concentrations of 10 heavy metals including Fe, Al, Mn, Co, Ni, Cu, Se, Cd, Cr and Pb were determined for water quality evaluation and health risk assessment. The results demonstrated that almost all of the tap water samples contained metal concentrations below the Chinese national standard limits for drinking water (GB 5749-2022). The risk of heavy metals in tap water to human health was evaluated, and the results showed that the total carcinogenic risk (TCR) was in the range of 10−6 and 10−4 and the hazard index (HI) was much lower than one in both summer and winter. The current tap water in Wuhan is generally in a relatively safe state and will not cause acute hazards or chronic diseases in the short term, but the long-term cancer risk is still noteworthy. The heavy metal pollution index (HPI) showed that the overall water quality of urban drinking water sources in Wuhan has been satisfactory, despite its slightly polluted state in winter. Pipeline corrosion was considered as one of the important sources of heavy metals in Wuhan tap water, which can explain, to a certain extent, the increase in the heavy metal concentrations of tap water outlets relative to the finished water reported by waterworks, such as Fe, Ni, Cd and Pb. This study has implications for the formulation of better urban water supply security management strategies and associated sustainability challenges.

Deposition of DLC film on the inner surface of N80 pipeline by hollow cathode PECVD

The corrosion and wear of N80 pipeline in oil and gas field environment has always been an urgent problem to be solved in the field of oil and gas exploitation. DLC film is considered to be an effective material for prolonging the service life of pipeline due to its excellent properties. However, it is very difficult to deposit a uniform DLC film on the inner surface of long pipeline. In this paper, DLC film was deposited on the inner surface of a 1 m-long N80 pipeline with an inner diameter of 75 mm by hollow cathode plasma enhanced chemical vapor deposition (HC-PECVD) using the pipeline itself as the deposition chamber and cathode. The uniformity of microstructure, mechanical properties, corrosion resistance and tribological properties of DLC film were discussed. The results show that the DLC film deposited on the inner surface of N80 long pipeline by HC-PECVD equipment possesses excellent axial uniformity. The deposition of DLC film increases the corrosion potential and reduces the corrosion current density, which greatly improves the corrosion resistance of N80 pipeline. In addition, the deposition of DLC film also reduces the friction coefficient and wear rate, which greatly improves the wear resistance of N80 pipeline. Therefore, the deposition of DLC film is an effective protection method for the inner surface of N80 pipeline, which prolongs the service life of the pipeline. HC-PECVD equipment with pipeline as cavity uniformly deposits DLC film on the inner surface of long pipeline, which is a potential deposition method to prolong the service life of long pipeline in oil and gas exploitation.

An Approach for Easy Detection of Buried FRP Composite/Non-Metallic Pipes Using Ground-Penetrating Radar.

Pipelines remain the safest means of transporting natural gas and petroleum products. Nonetheless, the pipeline infrastructure in the US is facing major challenges, especially in terms of corrosion of steel/metallic pipes and excavation damage of onshore pipelines (leading to oil spills, explosions, and deaths). Corrosion of metallic pipelines can be avoided by using non-corrosive materials such as plastic pipes for low-pressure applications and glass-fiber-reinforced polymer (GFRP) composite pipes for transporting high-pressure oil and natural gas. However, buried non-metallic pipelines are not easily detectable, which can lead to increased excavation damage during construction and rehabilitation work. Alternative strategies for making buried non-metallic pipes easily locatable using ground-penetrating radar (GPR) were investigated in this study. Results from this study have shown that using carbon fabric or an aluminum foil overlay on non-metallic pipes before burying in soil significantly increases the reflected GPR signal amplitude, thereby making it easier to locate such pipelines. The reflected GPR signal amplitude for pipe sections with carbon fabric or aluminum foil overlays was found to have increased by a factor of up to 4.5 over the control samples. The results also highlight the importance of selecting the appropriate antenna frequency for GPR surveys, since wet silt loam soil and clay significantly reduce the penetration depths of the radar signals produced by the GPR antennae.

Non thermal plasma synthesis of ZnO nanoparticles and their corrosion inhibition activity on XC70 mild steel pipeline in 1 M HCl acidic medium

This paper investigates the inhibitory efficiency of zinc oxide nanoparticles (ZnO Nps) as an eco-friendly inhibitor against the corrosion of XC70 mild steel pipelines in a 1 M HCl acidic medium. The ZnO Nps were synthesized using non thermal plasma, in particular the gliding arc discharge-assisted (GAD) method, a chemical solvent free and safe approach that utilizes humid air as the vector gas and distilled water as the solvent. Characterization techniques such as DLS, EDX, SEM, and XRD confirmed the positive zeta potential, hexagonal wurtzite structure, spheroidal shape, and median particle size of 65.6 nm for the synthesized ZnO Nps, respectively. To evaluate the corrosion inhibition efficiency, investigations were conducted utilizing electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) techniques at varying temperature range (298–333K). Results showed that increasing the concentration of ZnO Nps improved their ability to inhibit corrosion, with an optimum concentration of 70 mg/L achieving a high effectiveness of 90.71 % at ambient temperature. SEM analysis confirmed the formation of a protective barrier film on the inhibited substrate, effectively hindering the diffusion of corrosive ions. Furthermore, the DFT method was employed to examine the corrosion mitigation mechanism. These results demonstrate the significant inhibiting properties of ZnO Nps in preventing corrosion of XC70 mild steel in a 1 M hydrochloric acid environment.

Hydrophobization of petf-surfaces for water-in-oil emulsions separations

The technique of poly(ethylene terephthalate) track-etched membranes (PETF TMs) modification to increase of water-in-oil emulsions separations is developed. The water-in-oil emulsions separations by using PETF TMs with regular pore geometry and pore sizes 200 and 350 nm is described in the article. PETF TMs were modified with octadecyltrichlorosilane by spin-coating method to increase their hydrophobic properties. The results of changes in the pore diameters and the contact angle after PETF TMs modification are presented. The obtained samples were characterized by AFM, SEM and gas permeability test. Chloroform–water and n-hexadecane–water emulsions have been used as a test liquid for water-in-oil emulsions separations. At an operating vacuum of 700 mbar, the specific filtration performance of chloroform: water emulsions were 51.5 and 932.0 l/(m2 ⋅ h), hexadecane: water were 46.1 and 203.4 l/(m2 ⋅ h) for PETF-200 / OTS and PETF-350 / OTS, respectively. The degree of purification of emulsions by modified membranes according to the refractive index is of 100 %. Obtained membranes can be used to separate oil-water emulsions in order to prevent the corrosion of pipelines and changes of crude oil viscosity, as well as the treatment of water purification from oil industry waste.

CO2 Corrosion of X80 Steel under High Shear Flow Fields

Corrosion failure accidents owing to flow erosion and pipeline corrosion frequently occur during transportation. In this study, a high wall shear stress (WSS) experimental setup was established to conduct the online electrochemical corrosion test. The corrosion behavior of welded joints in NACE solution was studied by electrochemical experimental methods such as electrochemical impedance spectroscopy (EIS) and wire harness microelectrode (WBE). The results show that different areas of the welded joint show different corrosion phenomena in NACE solution. The weld metal (WM) has the significantly better corrosion resistance, while the base metal (BM) and heat-affected zone (HAZ) have worst corrosion resistance than WM. The current of the WM surface was cathodic current, while the current of the BM and HAZ surface were anode currents.

AC corrosion of steel pipeline under cathodic protection: A state‐of‐the‐art review

AbstractBy the advancement of the oil, electricity, and transportation industries, an increasing number of oil and gas pipelines were buried alongside high‐voltage alternating current (AC) transmission lines and electrified railways. This resulted in a growing issue of AC interference in buried pipelines. Previous studies have shown that the presence of AC interference can result in severe corrosion damage to metallic structures, even when cathodic protection (CP) is available. This paper provides a state‐of‐the‐art review on AC corrosion of cathodically protected pipeline steel. Specifically, attention is paid to research areas including influencing factors in AC corrosion for pipelines under CP, existing AC protection criteria, corrosion risk assessment based on probability of failure, numerical simulation in AC corrosion, and mitigation of AC corrosion. Each area of research is reviewed in detail and the corresponding technical gaps and future research opportunities are identified and discussed.

Computational fluid dynamics driven mass transfer model for the prediction of [formula omitted] corrosion in pipelines

A novel, computational fluid dynamics (CFD) driven modelling methodology for predicting CO2 corrosion rates in pipelines is presented. CFD is used to provide accurate predictions of the viscous sublayer thickness and turbulent diffusivities, which are then used within a mass transfer model of aqueous CO2 corrosion. Comparisons with experimental measurements of corrosion rate in horizontal pipe flow and corresponding theoretical predictions, based on empirical correlations and previous CFD approaches, show the new approach is more accurate for flows in the range of pH 4 to 6. However, the key advantage of the new approach is its flexibility. Existing models are inaccurate and highly restrictive, having been derived for very simple cases, such as 1 D pipe flow. In contrast, the new methodology provides a firm, scientific foundation for predicting corrosion rates by determining conditions in the viscous sublayer in much more complex, and practically relevant, flow situations.

Modeling of water film generation in up-inclined low liquid loading natural gas pipeline elbows and its implication on internal corrosion occurrence

Condensed water often accompanies natural gas in the transmission process. The water forms thin film when parameters such as temperature and pressure change. This accelerates pipeline corrosion and makes the pipeline wall become thinner. Severe corrosion can lead to pipeline rupture, endangering the pipeline safety and leading to economic losses. The distribution of a water film plays a significant role in the corrosion process, So the work of predicting the distribution of a water film and flow characteristics becomes a key priority when analyzing corrosion in a pipe elbow. In this study, Eulerian, RNG (re-normalization group) k-ε and Eulerian wall film models are employed to establish a pipe elbow model that predicts the locations of water phase accumulation. Combining with a limiting diffusion current density, this model can be used to predict the potential corrosion locations and extent. The proposed model is validated by using velocity and water film distributions and it shows substantial agreement with previous models and results in the literature. From the simulation outcomes, a water film is mainly distributed at bottom while the thickness of the water film increases significantly at the pipe elbow. At the elbow bottom the inlet gas velocity increases, this shifts the high corrosion rate zone from elbow rear to front. Corrosion at the elbow front is more serious regardless of the changes in the inlet liquid velocity, elbow angle or water holdup. Meanwhile, when the gas velocity or elbow angle is large, the water film gradually spreads from the elbow bottom to the side and top parts which are in a high corrosion rate zone and more dangerous. Therefore, weak positions where pipeline elbow corrosion failures may occur can be quickly and conveniently computed and determined by the proposed model.

Corrosion of pipelines in urban water systems: Current research status and future trends based on bibliometric analysis

The urban water systems are of vital importance to the society and the infrastructure is increasing largely due to population growth and urbanization. Corrosion is an inevitable problem faced by urban water pipelines, which causes not only the system failure leading to serious economic losses, but also the deterioration of drinking water quality. This paper quantitatively analyzed 3204 publications related to corrosion in urban water systems in the Web of Science (WoS) Core Collection Database since 1997 through bibliometric analysis. The results showed that research interest on corrosion in urban water systems increased exponentially, and the related publications mostly belonged to “Environmental sciences”, “Water resources” and “Environmental engineering” WoS categories. China and the USA have published far more papers than other countries, while Belgium is more influential with the highest citation per publication. Researchers collaborated actively globally, especially Chinese and American authors. The most cited publications showed that researchers mostly focused on the formation and composition of corrosion scales and deposits, and the release of contaminants such as heavy metals from them. The keyword analysis implied continuous research interests in lead leaching from corrosion scales in drinking water systems, and highlighted the hydrogen sulfide emission and the associated concrete biocorrosion in sewers. Future research suggestions were also proposed, including the adsorption and desorption of emerging contaminants from corrosion products in drinking water system, the effect of corrosion inhibitors and biocides dosed in sewers on the wastewater treatment processes and the biocorrosion mechanisms of the pipes in reclaimed water distribution system.

Topographical profiles and mechanical property of corrosion product films on a pipeline steel in Desulfovibrio vulgaris-containing thin electrolyte layer characterised by atomic force microscopy

ABSTRACT Internal corrosion of wet gas pipelines usually occurs in thin layers of water condensate with dissolved gases such as CO2, where a bacterial community can grow to cause microbiological corrosion. In this work, surface films generated during corrosion of an X52 pipeline steel under a CO2-containing thin electrolyte layer (TEL) in the absence and presence of Desulfovibrio vulgaris bacteria were characterised by atomic force microscopy. The film generated in the Desulfovibrio vulgaris-containing TEL, i.e. a mixture of FeS, FeCO3 and biopolymers, as compared with the film generated in the sterile TEL (i.e. FeCO3-dominant corrosion products), is topographically less compact and softer, with a reduced elastic modulus. After 7 days of immersion, the elastic modulus of the surface films generated in the sterile and D. vulgaris-containing TELs are 11.81 and 6.79 GPa, respectively.

Estimation of burst pressure of pipelines with interacting corrosion clusters based on machine learning models

Pipeline corrosion defects mostly appear in a colony such that they interact to reduce the failure pressure, which is not defined by features of a single corrosion defect. The huge amount of corrosion defects captured by in-line inspection tools including the variability of defect profile in pipelines and the dependence of the reliability assessment on such data pose significant research challenges in performance assurance. This highlights the need for computationally efficient modelling schemes to estimate the burst pressure of pipelines affected by both longitudinal and circumferential interacting corrosion defects. In the present paper, a novel approach is proposed for this purpose by combining supervised machine learning methods with 25 numerical models of corroded pipelines, validated with experimental results available from literature. Additionally, six improved composite defect shapes are proposed, resulting in 150 models to examine the non-linear behaviour of interacting corrosion defects by capturing the real the defect profiles captured by the In-line Inspection tools. The predicted failure pressures from the developed numerical models produced an absolute mean deviation of not exceeding 2.03% and 2.2% from the experimental burst pressure and the modified Mixed Type Interaction approach respectively, better than published results from the literature. Notably, the predicted failure pressures based on real pipeline data, infused with the generated artificial neural networks and non-linear regression models provide a total mean deviation of 3.1% and 7.3% respectively, thereby providing a path for effective maintenance planning.

Gas liquid-carried flow accelerates MIC by sulfate reducing bacteria biofilm

The corrosion and perforation leakage of shale gas pipelines can lead to serious environmental damage. By tracking the water and gas components throughout the shale gas production cycle, the main factors that affect corrosion in shale gas pipelines have been identified: carbon dioxide, dissolved oxygen, sulfate-reducing bacteria, and chloride ions. The study focused on understanding the development mechanism of localized corrosion of L360N steel within the upward shale gas gathering pipeline, particularly under the combined influence of sulfate-reducing bacteria and flowing conditions. SRB could form a biofilm on the surface of the steel. Through the Dissimilatory Sulfate Reduction (DSR) process, the metabolites reacted with Fe2+ to produce FeS. The corrosion rate of L360N steel was observed to be higher when exposed to gas-liquid flow compared to static conditions. In the flowing state, the boundary layer within the upward pipeline exhibited backflow tendencies, causing a portion of the corrosion products and biofilm to peel off. This exposure revealed a local surface, acting as an anode. As a result, corrosion pits were further deepened due to microscopic eddy currents, indicating that zero net liquid flow accelerated the corrosion process.

Monitoring and Preventing Failures of Transmission Pipelines at Oil and Natural Gas Plants

In recent years, the increase in energy prices and demand has been driven by the post-pandemic economic recovery. Of the various energy sources, oil and natural gas remain the most important source of energy production and consumption after coal. Oil and gas pipelines are a key component of the overall energy infrastructure, transporting oil and gas from mines to end users, so the reliability and safety of these pipelines is critical. The oil and gas industry incurs large expenses for the removal of failures related to, among others, corrosion of pipelines caused by the presence of Hg, CO2 H2S, carbonates and chlorides in reservoir waters. Therefore, pipeline operators must constantly monitor and prevent corrosion. Corrosion failure losses are a major motivation for the oil and gas industry to develop accurate monitoring models using non-destructive NDT methods based on test results and failure frequency observations. Observing the locations of frequent pipeline failures and monitoring and applying corrosion protection to pipelines play an important role in reducing failure rates and ultimately increasing the economic and safety performance of pipelines. Monitoring and prevention efforts support the decision-making process in the oil and gas industry by predicting failures and determining the timing of maintenance or replacement of corroded pipelines. We have presented methods of prevention through the use of corrosion inhibitors in crude oil and natural gas transmission pipelines, as well as various factors that influence their application. In this article, a review of corrosion rate monitoring systems is conducted, and a range of control and monitoring scenarios is proposed. This knowledge will aid scientists and practitioners in prioritizing their policies, not only to choose the appropriate monitoring technique but also to enhance corrosion protection effectiveness.

Investigation into main controlling factors and prediction model of L245NS steel corrosion rate in CO2–O2–SO2–H2S–H2O environment

Multi-component thermal fluid flooding is an increasingly mature technology for heavy oil recovery. However, the production of associated gas containing highly corrosive CO2/O2/SO2/H2S/H2O impurities can lead to corrosion and perforation failure in gathering pipelines. This study systematically investigated the effects of temperature/CO2/O2/SO2/H2S on L245NS steel corrosion in a CO2–O2–SO2–H2S–H2O environment and analyzed the correlation between these factors and corrosion rate. The corrosion behavior of L245NS steel in a CO2–O2–SO2–H2S–H2O environment was investigated through weight-loss experiments and surface characterization techniques. An empirical model for predicting the corrosion rate in this environment was established based on the obtained results. The results indicated that the sequence of importance for corrosion rate was as follows: O2 (0.8181) > H2S (0.7511) > Temperature (0.7491) > CO2 (0.7312) > SO2 (0.7017). Surface characterization revealed that the predominant corrosion products were FeCO3, FeS2, FeS, Fe(OH)3, FeOOH, Fe3O4, Fe2O3, elemental sulfur and FeSO4·4H2O. The corrosion reaction involved CO2/O2/SO2/H2S while synergistic reactions between SO2–O2 and SO2–H2S further promoted corrosion. Finally, an empirical model for the corrosion rate of L245NS steel in a CO2–O2–SO2–H2S–H2O environment was established. The fitting error ranged from 0.03% to 8.99%, and the verification error ranged from 2.62% to 14.83%. This model can provide a valuable reference for preventing and controlling pipeline corrosion.