Towards a Validated Pipeline Dent Integrity Assessment Model

Bolton, Brock; Semiga, Vlado; Dinovitzer, Aaron; Tiku, Sanjay; Alexander, Chris

doi:10.1115/ipc2008-64621

Cited by 7 publications

(5 citation statements)

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“…The calculated peak stress values for the dent exceeded the measured yield strength for the pipe, and the resulting residual stresses would make the pipeline more susceptible to stress corrosion and fatigue [26]. In addition, the change in geometry has been found to concentrate stresses sufficiently to enable fatigue cracking under cyclic loading conditions [3,25].…”

Section: Analysis and Discussionmentioning

confidence: 90%

“…Cyclic stresses enhance local strain around the pits, increase the rate of initiation and later propagation of these cracks [15,18,27]. The pipeline underwent cyclic loading during its lifetime, which has been described or modeled as a form of low-cycle fatigue [3,28]. The tests on the uncracked dented segment of pipe attempted to replicate this low-cycle fatigue.…”

Section: Analysis and Discussionmentioning

confidence: 99%

“…One of the issues studied are dents in pipelines. Dents can create stress risers in the pipe, allowing initiation sites for fatigue and stress corrosion cracking (SCC) [3]. In addition, dents damage the protective coatings on the pipe surfaces, allowing water, microbes, and other contaminants to contact the pipe metal surface [1].…”

Section: Introductionmentioning

confidence: 99%

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Investigation and Recommendations on Bottom-Dented Petroleum Pipelines

Mueller

Liu

Chhatre

et al. 2017

J Fail. Anal. and Preven.

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On September 21, 2015, the National Transportation Safety Board responded to a petroleum leak from a transmission pipeline in Centreville, VA. A small through crack was found leaking at a dent on the underside of the pipe, located away from any welds. The investigation found that corrosion fatigue could initiate at small dents, typically caused by impingement. While top-side dents from excavation and servicing have well-been documented and regulated, bottom-side dents, deemed acceptable per regulations, were found to be susceptible to stress corrosion and fatigue cracking. This investigation explored multiple and fundamental aspects of cracking in steel pipe dents, including nondestructive inspection, electron microscopy, finite element modeling, and long-term cyclic loading tests to characterize the cause of this pipeline accident.

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Section: Analysis and Discussionmentioning

confidence: 90%

Section: Analysis and Discussionmentioning

confidence: 99%

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Investigation and Recommendations on Bottom-Dented Petroleum Pipelines

Mueller

Liu

Chhatre

et al. 2017

J Fail. Anal. and Preven.

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“…1 Specimen tested only in air (not buried or not repaired). 2 Results of specimen #3 (see reference [10]) and specimen #18 not presented due to tests carried out under different conditions. 3 Not measured at the same site area where DIC showed the maximum strain, see reference [12].…”

Section: Discussionmentioning

confidence: 99%

“…The fatigue behavior of pipeline specimens with dents under cyclic internal pressure loading, with and without restriction constraints to free deformation, have been studied by different researchers (e.g., see [1][2][3][4][5][6][7][8][9]). Although dent depth criteria are the most frequently used in the industry for their ease of application, the determination of cyclic strains operating on the dent hot spots are needed to enhance the accuracy of fatigue life predictions.…”

Section: Introductionmentioning

confidence: 99%

Fatigue Tests on Buried or Repaired Dented Steel Pipeline Specimens

Paiva

Gonzáles

Vieira

et al. 2021

Metals

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This paper presents the results of fatigue tests performed on dented steel pipeline specimens that were tested under different environmental conditions and subjected to cyclic internal pressure. Thirty-three pipe specimens were divided into three groups and tested under three different conditions. A first set of nine dented specimens was tested in air without any restrictions. A second set of eight specimens was tested while buried in the soil. A third set of sixteen specimens was tested in air, after the dents had been repaired by composite material sleeves. Hot-spot cyclic strain amplitudes were measured using two experimental techniques: Digital Image Correlation (DIC) and Fiber Optic Bragg Strain Gauges (FBSG). At first, all thirty-three specimens were tested in air along five full cycles in order to carry out full-field measurements using DIC to identify and quantify strain concentration at sites that were potential locations for fatigue cracks to initiate. Close to these point-locations, measurements of strains using FBSG were also made, and the results were then compared with the DIC results. FBSG were also used during the cyclic pressure loading process while the specimens were being tested, in such a way as to monitor the influence of the environment in the dented areas. The test results demonstrated that a simple uniaxial Manson-Coffin fatigue equation that uses the universal exponents proposed by Manson, together with the circumferential strain amplitude measured at the hot spots can be used to predict the fatigue life of the dented specimens. Moreover, it was determined that the measured strains at the hot-spot locations were not influenced by the soil coverage, although showing a considerable and beneficial decrease in their amplitudes caused by the composite repair reinforcements.

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