External corrosion of oil and gas pipelines: A review of failure mechanisms and predictive preventions (original) (raw)
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Investigation of Corrosion Induced Degradation in Oil Pipelines
https://www.ijrrjournal.com/IJRR\_Vol.6\_Issue.6\_June2019/Abstract\_IJRR0052.html, 2019
Corrosion has been identified as a major concern in the oil and gas industry. To this end, the study investigated the corrosion induced degradation in oil pipelines within the South-South geo-political region of Nigeria. To achieve this, Direct Field Assessment Method (DFAM) was used to obtain field data because it helps ascertain which corrosion type prevails in the selected regions, since pipelines are susceptible to various kinds of corrosion depending on the potential difference between the pipe and the ground surface within a corrosive environment. The reliability and the failure rate of these pipelines in the Niger Delta regions due to corrosion were determined. Results reveal that 70.83% of the pipeline corrosion that occurs in the South-South geo-political region of Nigeria from 1999-2015 is due to Stress Corrosion Cracking (SCC) and that there is a seemingly correlation between the 3 rd party activity (vandalism) and corrosion. This is because the areas with higher 3 rd party activity have corresponding higher failure rate and corrosion occurrence. However, despite the effect of 3 rd party activities and corrosion activities, the reliability result suggests that the oil pipelines are still within their useful life stage.
A Review of Field Corrosion Control and Monitoring Techniques of the Upstream Oil and Gas Pipelines
Nigerian Journal of Technological Development, 2018
All steel pipelines used in hydrocarbon transportation are susceptible to either electrolytic or galvanic corrosion attack which deteriorate with time leading to failure even before end of design life. Consequences of corrosion attack and eventual failure of pipelines within oil and gas industry has been classified into economic, health, safety and environmental impacts. The present study considers detailed review of practical field corrosion control and monitoring mechanisms necessary to preserve, extend service life of pipelines and reduce corrosion impacts. The corrosion controls are various preventive strategies considered during construction and prior to pipelines' commissioning which include design, material selection, protective coating, chemical treatment and cathodic protection system. But the corrosion monitoring strategy is aimed at establishing condition of pipelines and environmental variables that may accelerate corrosion process and this includes potential survey, bacteria count, corrosion coupons and intelligent pigging. The identified corrosion control and monitoring techniques are not governed by any industry code and standard but has been generally accepted as best practice within the oil and gas industry as ways of combating corrosion and evaluating pipelines condition. Therefore, effective implementation of the identified corrosion control and monitoring strategies would limit corrosion attack and guide pipelines' operators to make informed decision and timely respond to corrosion threat before failures.
ISRN Corrosion, 2012
Effective management of assets in the oil and gas industry is vital in ensuring equipment availability, increased output, reduced maintenance cost, and minimal nonproductive time (NPT). Due to the high cost of assets used in oil and gas production, there is a need to enhance performance through good assets management techniques. This involves the minimization of NPT which accounts for about 20-30% of operation time needed from exploration to production. Corrosion contributes to about 25% of failures experienced in oil and gas production industry, while more than 50% of this failure is associated with sweet and sour corrosions in pipelines. This major risk in oil and gas production requires the understanding of the failure mechanism and procedures for assessment and control. For reduced pipeline failure and enhanced life cycle, corrosion experts should understand the mechanisms of corrosion, the risk assessment criteria, and mitigation strategies. This paper explores existing research in pipeline corrosion, in order to show the mechanisms, the risk assessment methodologies, and the framework for mitigation. The paper shows that corrosion in pipelines is combated at all stages of oil and gas production by incorporating field data information from previous fields into the new field's development process.
Durability of the Oil Pipeline Systems Under Environmental Effects
THE IRAQI JOURNAL FOR MECHANICAL AND MATERIALS ENGINEERING, 2019
Recent discoveries of petroleum and gas reserves in environments with severe operationalconditions metallic materials, carbon and low alloy steels, have pushed and prompted theneed to find alternatives. The presence of gaseous hydrogen may cause the suffering ofhydrogen damage and embrittlement. The effect of hydrogen and temperature on fatigue lifeproperties, have pushed the utilization of steel procurement specification even stricter thanthey used to be. The main modifications concern the mechanical resistance, toughness at lowtemperatures weld ability and resistance to embrittlement related to hydrogen.Aiming to enhance the reliability and operation of pipelines system, a study based on theelastoplastic fracture was carried out to determine high level prediction for the fatigue life,as well as to evidence the toughness resistance of the used materials. The materials testedhere are API 5L X70 and X100 micro alloyed steels. Hydrogen had affecting the materialproperties, which are r...
Key issues related to modelling of internal corrosion of oil and gas pipelines – A review
The state-of-the-art in modelling of internal corrosion of oil and gas pipelines made from carbon steel is reviewed. The review covers the effects of: electrochemistry, water chemistry, formation of protective scales and scales, temperature, flow, steel, inhibition, water condensation, glycol/methanol and localized attack. Various mathematical modelling strategies are discussed.
The effect of defect size and soil aggressivity on corrosion of underground oil gas pipelines
E3S Web of Conferences
Nowadays, the oil & gas industry has limited number of non-destructive corrosion techniques for assessment of life-time of existing infrastructures, especially on low and medium pressure pipelines exposed to aggressive soil environment where defect in isolation and presence of water formed ideal conditions for corrosion attack. Efficient non-destructive corrosion monitoring can be achieved using mobile potentiostat through the selection of appropriate monitoring techniques and special kind of sensor. OCP potential is monitored for 10 minutes and actual corrosion rate of pipeline with corrosion products in soil mixture was determined using Stern polarization technique in non-invasive arrangement. Using global database with range of minimum and maximum corrosion rate limits obtained from terrain measurements we can determine active or passive role of corrosion products and assess risk joint with aggressiveness of soil in location of interest. Finally, values were divided between high ...
Effect of Corrosion on Hydrocarbon Pipelines T
The demand of hydrocarbons has increased the construction of pipelines and the protection of the physical and mechanical integrity of the already existing infrastructure. Corrosion is the main reason of failures in the pipeline and it is mostly produced by acid (HCOOCH 3). In this basis, a CFD code was used, in order to study the corrosion of internal wall of hydrocarbons pipeline. In this situation, the corrosion phenomenon shows a growing deposit, which causes defect damages (welding or fabrication) at diverse positions along the pipeline. The solution of the pipeline corrosion is based on the diminution of the Naphthenic acid.
Procedia structural integrity, 2019
The calculation model is developed to evaluate the residual lifetime of a pipe with a crack considering in-service degradation of the pipeline steel and the effect of soil corrosion. The model is based on the first law of thermodynamics. The problem of determination of the period of subcritical crack growth in a pipe is reduced to the differential equation subjected to definite initial and final conditions. Obtained equation together with the boundary conditions are used for prediction of the residual lifetime of the pipe made of the X52 pipe steel. The pipe contains external surface semi-elliptical crack. The task consists in the determination of the time of crack propagation through the pipe wall till its decompression. According to the experimental data, cracks in the studied steel under long-term loading and soil corrosion propagate mainly at constant rate, which is different for the as-received pipeline steel and the steel after 30 years in service. Based on these data, the equation for approximate determination of the crack growth rate for arbitrary service time of the pipe made of the X52 steel is proposed. To evaluate the crack propagation time, the energy approach is employed. For a crack that remains semi-elliptical during propagation, the problem is reduced to the differential equation system that determines the variations of the crack semi-axes. The system solution under definite initial and final conditions renders the expression for the pipe residual lifetime. The dependences of pipe residual lifetime on initial crack depth and pipe operation time are derived. The strong influence of the time of steel previous service on the pipe residual lifetime is manifested.
Developing a Predictive Model of Near Neutral pH Stress Corrosion Cracking of Underground Pipelines
Volume 2: Pipeline Integrity Management, 2012
Near neutral pH Stress Corrosion Cracking (NNpHSCC) associated with external corrosion of pipelines is an issue facing industry today. Determining areas of NNpHSCC susceptibility is crucial to developing Integrity Management Programs and inspection dig schedules. This research involved collecting pertinent field data (inspection dig reports, failure reports, loading histories) and developing a predictive model to help identify areas and lines most susceptible to NNpHSCC. The predictive model focused on the loading history (in this case, SCADA data) patterns to classify different groups of loading conditions. Hydrogen has been identified and established in previous literature to be a major contributor to NNpHSCC. Different Hydrogen Enhancement Factors (HEF) were applied based on how the mechanisms of hydrogen embrittlement react to the respective loading conditions. The predictive model illustrated a dormancy behaviour, similar to the one seen in field conditions and a mechanically a...