Calculation of maximum allowable free span length and safety assessment of the DF1-1 submarine pipeline

Xu, Jishang; Li, Guangxue; Horrillo, Juan; Rong-min, Yang; Cao, Lihua

doi:10.1007/s11802-010-0001-4

Cited by 10 publications

(4 citation statements)

References 6 publications

(6 reference statements)

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“…Ketika lubang gerusan makin besar, dan bentang bebas pipa menjadi lebih panjang dari Maximum Allowable Free Span Length (MAFSL), maka pada pipa dapat terjadi Vortex Induced Vibrations (VIV) akibat hempasan arus dan gelombang. Dengan demikian, penentuan MAFSL dalam berbagai kondisi menjadi sangat penting dalam merancang jaringan pipa baru maupun untuk mengatasi masalah pipa yang sudah ada [1]. Hal ini diatur dalam code dan standard misalnya dari DNV 1981 dan DNV RP C205.…”

Section: Pendahuluanunclassified

Analisis Panjang Span Maksimum yang Diizinkan Akibat Vortex Shedding Pada Riser KLB Platform

Hamzah¹,

Prastianto²,

Rosyid³

2022

JTITS

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Abstrak-Sistem pipa bawah laut/riser yang dipasang pada kedalaman tertentu di laut berkemungkinan mengalami kegagalan akibat beban hidrodinamik seperti gelombang dan arus, salah satunya dapat menyebabkan terjadinya Vortex Induced Vibration (VIV). Jika hal ini tidak dianalisis dalam tahap desain pipa/riser yang memiliki bentangan bebas (free span) maka sistem pipa tersebut dapat mengalami kegagalan. Dalam penelitian ini dilakukan analisis Maximum Allowable Free Span Length (MAFSL) pada riser KLB platform yang berlokasi di lepas pantai Jawa Barat sebelah utara sekitar 80-200 km timur laut Jakarta. KLB platform merupakan salah satu dari lima platform yang direncanakan oleh Pertamina Hulu Energi Offshore Northwest Java (PHE ONWJ) untuk dilakukan penggantian dan pemasangan jaringan pipa yang baru. Analisis MAFSL pada riser KLB platform yang memiliki ukuran diameter luar 323,9 mm dan panjang 1 km ini dilakukan dengan bantuan software MathCAD, serta berdasar code dan standard DNV RP C205 dan DNV 1981. Hasil penelitian ini menunjukkan bahwa panjang span dari titik clamp elevation 0,610 m ke -7,620 m yaitu 8,23 m masih aman karena nilainya tidak melebihi MAFSL yaitu 16,042 m dan dari titik clamp elevation -7,620 m ke -15,00m panjang span juga masih aman yaitu 7,38m karena tidak melebihi MAFSL yaitu 21,517 m.

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Section: Pendahuluanunclassified

Analisis Panjang Span Maksimum yang Diizinkan Akibat Vortex Shedding Pada Riser KLB Platform

Hamzah¹,

Prastianto²,

Rosyid³

2022

JTITS

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“…The static analysis method is used to calculate the maximum allowable free span length through the maximum bending moment . Xu et al (J. Xu, Li, Horrillo, Yang, & Cao, 2010) gives the maximum bending moment equation as:…”

Section: Static Analysismentioning

confidence: 99%

“…The static analysis of the pipeline was carried out using a stress-based method. This involves: calculating the maximum bending moment; calculating the allowable stress; and calculating the maximum allowable free span. The static analysis method is used to calculate the MAFSL through the maximum bending moment M MAX . Xu et al (2010) give the maximum bending moment equation as: But, it is usually taken as: Assuming marine growth is negligible. The maximum bending moment can be also expressed in terms of allowable bending stress σ b and the pipeline properties called the section modulus z and the second moment of area of the pipe section I: where: Substituting equation (22) into equation (19), the maximum allowable span length L will be: BS PD 8010 (BSI, 2004) gives the hoop stress for pipelines that satisfy the condition Dt>20 as: And, Poisson’s effect based on the maximum hoop stress can be determined as: v = 0.3. PD 8010-2 recommends that the allowable stress should be less than the SMYS by a factor of safety f d which is the design factor: Based on this standard, a design factor of 0.72 has been used for the seabed and 0.6 for risers and landfalls. The maximum combined stress can be calculated based on the specified minimum yield strength as: Also, the maximum combined stress can be calculated based on the von Mises equation as: Combining equation (29) and equation (30) gives: The longitudinal stress in tension and the longitudinal stress in compression is obtained when Poisson’s effect is subtracted from both roots of σ L .…”

mentioning

confidence: 99%

Review of pipeline span analysis

Shittu

Kara

Aliyu

et al. 2019

WJE

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Purpose The purpose of this paper is to mainly review the state-of-the-art developments in the field of hydrodynamics of offshore pipelines, identifying the key tools for analysis of pipeline free spans, their applications, their qualifying characteristics and capabilities and limitations. Design/methodology/approach These different analytical, numerical and semi-empirical tools available for predicting such hydrodynamic loads and their effects include VIVANA, PIPESIN, VIVSIM, SIMULATOR, FATFREE, amongst others. Inherent in these models are current effects, wave effects and/ or pipe–soil interactions. Findings Amongst these models, the most attention was given to the new VIVANA model because this model take into account the vortex-induced effects with respect to free-spanning pipelines (which have dominant effect in the span analysis in deep water) better than other semi-empirical models (such as Shear 7). Recent improvements in VIVANA include its ability to have arbitrary variation in speed and direction of current, as well as the ability for calculation of pure IL and combined IL-CF response. Improvements in fatigue assessments at free spans, i.e. pipe–soil interaction have been achieved through the combined frequency domain and non-linear time domain analysis methodology adopted. Semi-empirical models are still the de facto currently used in the design of free-spanning pipelines. However, there is need for further research on free-span hydrodynamic coefficients and on how in-line and cross-flow vibrations interact. Again, there is still the challenge due to VIV complexity in fully understanding the fluid structure interaction problem, as there is no consolidated procedure for its analysis. It has been observed that there is large scatter between the different codes adopted in the prediction of fatigue damage, as there lacks full-scale test data devoted to determination/validation of the coefficients used in the semi-empirical models. A case study of the preliminary design of a typical 48 in. pipeline has been presented in this study to demonstrate the use of the free-span analysis tool, DNV RP F105. Excel spreadsheet has been applied in the execution of formulas. Originality/value This review paper is the first of its kind to study the state-of-the-art development in pipeline free-span analysis models and demonstrate the use of analysis tool, DNV for MAFSL calculation. Hence, information obtained from this paper would be invaluable in assisting designers both in the industry and academia.

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“…A batch of studies conducted until 2006 only was responsible for a particular case that could not be extended to other states [8]. Other studies of fatigue capacity were obtained laboratory ally [11]. In 2006, DNV provided a general instruction that could be generalized to all modes.…”

Section: Fatigue Damagementioning

confidence: 99%

Evaluation of Vortex Induced Vibration Effective Parameters on Free-Span Subsea Pipelines

Sharifi

Tasdighi

2019

ijcoe

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Subsea pipelines due to the reduction of transfer costs and expedite the offshore operations is one of the all-purpose structures in marine industries. Subsea pipelines are exposed to a variety of hazards, including corrosion and fatigue Etc. Free span exacerbates the fatigue required parameters due to a phenomenon called the Vortex Induced Vibration (VIV). In this research, the influence of the span's length on the free span subsea pipeline has been reviewed with ABAQUS standard code. In this study the previous result has been expanded. The results of the VIV fatigue life are extensible to all of the depth. Achieved Results indicate that the fatigue life of the pipeline even in the worst condition is much higher than the required amount that it represents the upstream design of DNV-RP-F105. In this study the backrest pipeline has been investigated and result show that the pipeline under the different conditions in the backrest, by creating more vibration and displacement on one side of the pipeline reduces the fatigue life of 113 percent compared to snap. The VIV fatigue life has undergone a lot of changes due to span length changes, maximum changes occur between cable and behavioral which the amount of these changes is reduced by 75%. The free span length is another factor in VIV fatigue. VIV fatigue life will be increased by reducing the span length. As well as increasing the flow velocity that is the main factor in creating the VIV is increased fatigue. Therefore, in terms of the accuracy in the choice of the existing conditions of very high importance for the pipeline. Comparison between effect parameters in VIV fatigue life was shown that span length is the most effective parameter.

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Calculation of maximum allowable free span length and safety assessment of the DF1-1 submarine pipeline

Cited by 10 publications

References 6 publications

Analisis Panjang Span Maksimum yang Diizinkan Akibat Vortex Shedding Pada Riser KLB Platform

Analisis Panjang Span Maksimum yang Diizinkan Akibat Vortex Shedding Pada Riser KLB Platform

Review of pipeline span analysis

Evaluation of Vortex Induced Vibration Effective Parameters on Free-Span Subsea Pipelines

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