Reliability assessment of free spanning subsea pipeline

Shabani, Mohammad Mahdi; Taheri, Abdolrahim; Daghigh, Mohammad

doi:10.1016/j.tws.2017.08.026

Cited by 25 publications

(8 citation statements)

References 8 publications

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“…Hydrodynamic loads according to the first flow regime in Section 2 should be calculated based on equation (7) and Table 4. We have Steps of designing a submarine pipe [18].…”

Section: Numerical Analysis and Discussionmentioning

confidence: 99%

Free Span Analysis for Submarine Pipelines

Pour

Taheri

abyaneh

2021

Shock and Vibration

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Pipelines are one of the most important and key elements that align with transferring hydrocarbon products in coastal and offshore industries which are exposed at various risks during their servicing. In this project, we are studding and describing free spanning of marine pipeline based on DNVGL-RP-F-105 regulation applying the finite element method by Abaqus software. For modeling, case studies of Gorze to Kish oil pipeline have been used. In order to provide and study the integrity of the structure against fatigue, the exact place as well as the free span length using software under environmental loading based on DNVGL-RP-F205 has been determined. Since based on DNVGL-TS-F101 free span causes local buckling, fatigue, and pipe burst then given to the servicing as well as environmental conditions, pipe condition has been monitored. Finally, using sensitivity analysis, the effect of different soil classes, elasticity module, and temperature on the pipe condition has been studied. At the end, the question if it is allowed to use a cross model for bed has been answered in previous studies.

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“…Hydrodynamic loads according to the first flow regime in Section 2 should be calculated based on equation (7) and Table 4. We have Steps of designing a submarine pipe [18].…”

Section: Numerical Analysis and Discussionmentioning

confidence: 99%

Free Span Analysis for Submarine Pipelines

Pour

Taheri

abyaneh

2021

Shock and Vibration

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“…Pipeline bends may occur downward or upward during either spanning or buckling. Ocean currents can scour the soil underneath the pipeline to cause free spanning, where a segment of the pipeline becomes unsupported except at the two ends of the free span length [4], [5]. For a The associate editor coordinating the review of this manuscript and approving it for publication was Laxmisha Rai .…”

Section: Introductionmentioning

confidence: 99%

Low-Cost and High-Efficiency Method for Detecting Vertical Bends of Subsea Pipelines

et al. 2020

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Subsea pipelines often bend upward due to vertical buckling or downward due to spanning and seabed settling. Typically, harsh environments and the difficulty of accessing underwater pipelines make the inspection and monitoring of subsea pipeline bends a challenging task. This paper demonstrates a lowcost, high-efficiency, and quasi-real-time method for detecting the vertical bends of subsea pipelines by using an in-pipe spherical detector (SD) with rolling features and a low blockage risk. When the SD rolls forward inside a bent pipeline, its rolling speed will change as it moves uphill and downhill, which can be indicated by the centripetal acceleration-the DC component of the recorded rolling acceleration signals. To achieve a high bend detection performance, the mass of the SD should be distributed in a centered disc area to make the SD capable of stably rolling around one of the sensitive axes of the accelerometer, and the accelerometer should be kept as far from the rotation axis as possible. It is experimentally demonstrated that a convex/concave DC component indicates that the pipe is bent downward/upward, and the bend detection resolution can reach 1 cm for a 12 m pipeline.

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“…The research on subsea pipeline spanning mainly focuses on the mechanical response analyses of the spanning sections under waves and currents [6], [10], [11], and the stability and reliability assessment [12], [13] of subsea pipelines. These studies provide forward guidance for how to safely lay subsea pipelines to avoid spanning and how to predict the spanning existence, but do not address how to directly detect existing spanning for pipeline reinforcement [13].…”

Section: Introductionmentioning

confidence: 99%

“…The influences of pipeline specifications and support conditions are sophisticatedly modeled to judge whether spanning will occur and predict the resonance frequency of the free spanning subsea pipeline [14], [15]. By predicting current-induced scour beneath subsea pipelines in areas with small spanning depths, the reliability of the free spanning pipeline can be assessed in advance and large spanning can be avoided by backfilling dinas or installing extra supports [12], [16]. Since many of the model parameters are simplified, screening may be too strict or too loose, leading to excessive reinforcement or missed inspections.…”

Section: Introductionmentioning

confidence: 99%

Vibration Detection of Spanning Subsea Pipelines by Using a Spherical Detector

et al. 2019

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This paper proposes a method for detecting the vibration of subsea spanning pipelines by using a spherical detector (SD) equipped with a triaxial accelerometer. The mathematical analyses and experiments demonstrate that the acceleration modulus square (AMS) and the AMS of the ac components (AMS_AC) of the acceleration signals recorded by the SD have one characteristic component whose frequency is equal to and can be used to determine the pipeline vibration frequency. As the amplitude of this component is immune to the rotation noises of the SD, its signal-to-noise ratio is higher than that of other components whose frequencies are the mixture of the vibration and rotation frequencies. Removing the dc bias along the three sensitive axes can eliminate other characteristic frequencies to make the AMS_AC having the unique frequency to indicate the pipeline vibration. The vibration frequency can be accurately and sensitively identified by using the AMS_AC. The detection thresholds of 5-, 10-, and 15-Hz vibrations are 0.6, 0.4, and 0.2 mm with regard to the amplitude, respectively.

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Reliability assessment of free spanning subsea pipeline

Cited by 25 publications

References 8 publications

Free Span Analysis for Submarine Pipelines

Free Span Analysis for Submarine Pipelines

Low-Cost and High-Efficiency Method for Detecting Vertical Bends of Subsea Pipelines

Vibration Detection of Spanning Subsea Pipelines by Using a Spherical Detector

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