Failure analysis of stress corrosion cracking occurred in a gas transmission steel pipeline

Sadeghimeresht, Esmaeil; Shahrabi, T.; Neshati, J.

doi:10.1016/j.engfailanal.2010.11.014

Cited by 118 publications

(24 citation statements)

References 9 publications

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“…Industrial experience has shown that severe localized corrosion issues such as pitting, microbiological induced corrosion and stress corrosion cracking can still occur within these structures, and these occurrences are often related to disbonded coatings. [1][2][3][4][5][6] Coating disbandment is common in buried pipes, particularly when CP is applied, 3,7 leading to the formation of a crevice (or gap) between the metal surface and the disbonded coating layer. Solution from the surrounding environment can access these crevices, resulting in enclosed corrosive environments.…”

mentioning

confidence: 99%

Electrochemical Method for Studying Localized Corrosion beneath Disbonded Coatings under Cathodic Protection

Varela

Tan

Forsyth

2015

J. Electrochem. Soc.

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This paper presents a new method for measuring localized corrosion under disbonded coatings by means of an electrochemical sensor, denoted differential aeration sensor (DAS). It measures the distribution of electrochemical currents over an electrode array surface partially covered by a crevice that simulates a disbonded coating. The DAS has been evaluated using immersion tests at open circuit and under cathodic protection (CP) conditions. Under both conditions, anodic as well as cathodic current densities were detected within the crevice. A fundamental understanding for the detection of anodic currents under CP has been explained in terms of basic electrochemistry. Based on the current distribution data provided by the sensor, two different analysis methods have been used to estimate corrosion and its distribution. These methods consisted of a direct application of Faraday's Law to the anodic currents detected by the array, and on a sensor-specific method denoted 'corrected currents' method. It has been demonstrated that under diffusion controlled conditions this latter method produces a better corrosion estimation than the direct application of Faraday's Law. The 'corrected currents' method allowed the estimation of corrosion patterns outside the crevice under CP. Good correlation between electrochemical calculations and surface profilometry results has been obtained. Cathodic protection (CP) is typically applied in combination with barrier coatings to prevent corrosion of steel on buried structures such as in water and energy pipelines. However, this combination is not always effective. Industrial experience has shown that severe localized corrosion issues such as pitting, microbiological induced corrosion and stress corrosion cracking can still occur within these structures, and these occurrences are often related to disbonded coatings. [1][2][3][4][5][6] Coating disbandment is common in buried pipes, particularly when CP is applied, 3,7 leading to the formation of a crevice (or gap) between the metal surface and the disbonded coating layer. Solution from the surrounding environment can access these crevices, resulting in enclosed corrosive environments. Furthermore, the effectiveness of the applied CP is believed to decrease significantly within the crevice due to a phenomenon often referred to as cathodic shielding. This phenomenon is particularly serious for buried pipelines, because the typically resistive soil solution could prevent CP current from reaching deep into the crevice created by the disbondment. [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] Disbonded coatings are generally considered a 'worst case scenario' for pipeline corrosion. Therefore, early detection of insufficient CP and corrosion within such crevice environments is critical.Potential survey methods, currently used by the pipeline industry, are not able to provide information about the CP effectiveness under a disbonded coating.Whilst the use of in-line metal loss inspection tools can detect pipeline corrosion (includ...

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mentioning

confidence: 99%

Electrochemical Method for Studying Localized Corrosion beneath Disbonded Coatings under Cathodic Protection

Varela

Tan

Forsyth

2015

J. Electrochem. Soc.

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“…CAESAR II software checking method is based on the American ASME B31.4 Pipeline Transportation Systems for Liquid Hydrocarbons and other Liquids, it is recommended that pipeline stress should not exceed the 90% of the pipeline allowable stress [3][4][5]. Case study of suspended oil pipelines.…”

Section: Check Criterion Of the Oils Pipelinesmentioning

confidence: 99%

Suspended Oil Pipeline Stress Sensitivity Analysis

Wu¹,

Lu²,

Peng³

et al. 2014

Recent Advances in Material, Analysis, Monitoring, and Evaluation in Foundation and Bridge Engineering

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Buried oil pipelines can traverse hundreds of kilometers of terrain with varied environmental and geotechnical conditions, such as earthquake prone areas. These areas experience ground subsidence, will lead to pipeline being suspended, the suspended segment of pipeline may result in pipeline rupture. Suspended oil pipeline stress safety usually has two contributing factors: the length of suspended segment and water buoyancy. In order to research the influence that the two contributing factors cause on the stress of suspended pipeline, it is needed to analyze suspended pipeline stress using analysis software CAESAR II. Research shows that, the buoyancy of water is more sensitive, and suspension pipe length of oil pipe is relatively small. It is provided with some reference results for pipeline safety management.

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“…Based on above, CAESAR II is applied for a stress analysis to the pipelines that crossing the river, the stress distribution is identified; stress concentration points are clearly located, which aim to make sure the safety of pipelines operation [2][3][4].…”

Section: Introductionmentioning

confidence: 99%

Stress Analysis of the Large Excavation River-Crossing Oil Pipeline

Wu¹,

Lu²,

Wu³

et al. 2014

Recent Advances in Material, Analysis, Monitoring, and Evaluation in Foundation and Bridge Engineering

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Stress concentration of the crossing oil pipeline is the main reason for pipeline failure. Currently, the study on the stress analysis of large excavation crossing river oil pipeline also seldom, in order to ensure the safe operation of the pipeline, it is necessary to do analysis of crossing river oil pipeline stress distribution under operating conditions. We do the numerical simulation of the a certain oil pipeline with large excavation method using stress analysis software CAESAR II, come to the distribution of the pipeline, and check whether it can meet the strength requirements or not. Through the engineering case study, we draw that the maximum stress generated at saddle weight under the operating conditions, it means that the saddle weight location is the dangerous section of the crossing river pipeline. Analyze and compare primary stress and secondary stress can come to that temperature difference is the main factor which generates stress in oil pipeline, while the impact of internal pressure is less.

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Failure analysis of stress corrosion cracking occurred in a gas transmission steel pipeline

Cited by 118 publications

References 9 publications

Electrochemical Method for Studying Localized Corrosion beneath Disbonded Coatings under Cathodic Protection

Electrochemical Method for Studying Localized Corrosion beneath Disbonded Coatings under Cathodic Protection

Suspended Oil Pipeline Stress Sensitivity Analysis

Stress Analysis of the Large Excavation River-Crossing Oil Pipeline

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