Abstract
Rupture of the outer sheath is one of the most common types of damage to unbonded flexible riser (UFR), which leads to tensile armor layers (TALs) direct contact with seawater and may induce localized corrosion in the wires. This seriously affects the safety of UFRs in service. In this article, a numerical model of UFR is developed. The errors between the tensile stiffness calculated by the model and experimental results are 7.16% and 6.75% under boundary conditions of limiting and allowing top-end axial torsion, respectively, verifying the model's correctness. The numerical model was used to study the effect of depth and length of localized belt corrosion and number of corroded wires on the tensile response of UFR, and it was found that tensile armor wire stress concentration occurred at the localized corrosion, and the relationship between localized corrosion depth and ultimate load was a third-degree polynomial; discussing the influence of belt corrosion spacing and combined corrosion interaction on the ultimate load, it was found that the combined corrosion depth and the ultimate load show a segmented linear relationship. The research on this article can provide theoretical support for the prediction of the ultimate load assessment of UFR under different corrosion conditions.
References
1.
Li
, X.
, Vaz
, M. A.
, and Barata Custódio
, A.
, 2023
, “A Finite Element Methodology for Birdcaging Analysis of Flexible Pipes With Damaged Outer Layers
,” Marin. Struct.
, 89
, p. 103397
. 2.
Wu
, S.
, Yang
, Z.
, Yin
, Y.
, Lu
, Q.
, Chen
, J.
, Yue
, Q.
, Yan
, J.
, and Gao
, B.
, 2021
, “Study on Failure Prediction Methodology of Flexible Pipes Under Large Torsion Considering Layer Interaction
,” ASME J. Offshore Mech. Arct. Eng.
, 143
(3
), p. 031801
. 3.
de Sousa
, J. R. M.
, de Sousa
, F. J. M.
, de Siqueira
, M. Q.
, Sagrilo
, L. V. S.
, de Lemos
, C. A. D.
, and Larsen
, C. M.
, 2012
, “A Theoretical Approach to Predict the Fatigue Life of Flexible Pipes
,” J. Appl. Methods
, 2012
(8
), pp. 1
–29
. 4.
Chen
, Y.
, He
, M.
, Zong
, Y.
, Dong
, S.
, Yan
, Y.
, Zhang
, Y.
, Liu
, H.
, and Cao
, J.
, 2021
, “Research Progress on Failure Modes of Unbonded Flexible Pipe and Their Control Measures
,” Nat. Gas Ind.
, 41
(11
), pp. 122
–131
. 5.
Drumond
, G. P.
, Pasqualino
, I. P.
, Pinheiro
, B. C.
, and Estefen
, S. F.
, 2018
, “Pipelines, Risers and Umbilicals Failures, a Literature Review
,” Ocean Eng.
, 148
, pp. 412
–425
. 6.
Anderson
, K.
, Keeffe
, B.
, and MacLeod
, I.
, 2007
, “IN-Service Repair of Flexible Riser Damage Experience With the North Sea Galley Field
,” 26th International Conference on Offshore Mechanics and Arctic Engineering
, San Diego, CA
, June 10–15
, Vol. 3, pp. 10
–15
.7.
Silva
, P.
, Svenningsen
, G.
, Dugstad
, A.
, and Gomes
, J. A. C. P.
, 2022
, “The Effect of Oxygen on the CO2 Corrosion of Tensile Wires in Simulated Annulus Environments of Flexible Pipes
,” Mater. Corros. Werkstoffe Korros.
, 73
(5
), pp. 669
–686
. 8.
Silva
, P.
, Senatore
, E.
, and Gomes
, J. A. C. P.
, 2023
, “Corrosion of Tensile Wires Covered with PA11 Layers in Simulated Annulus Environments at low CO2 Pressure
,” Mater. Corros. Werkstoffe Korros.
, 74
(2
), pp. 306
–319
. 9.
Eriksen
, M.
, and Engelbreth
, K. I.
, 2014
, “Outer Cover Damages on Flexible Pipes: Corrosion and Integrity Challenges
,” ASME 2014 33rd International Conference on Ocean, Offshore and Arctic Engineering
, San Francisco, CA
, June 8–14
, p. 24147
.10.
Barnes
, P.
, 2014
, “An Investigation Into the Corrosion Fatigue Behaviour of High Strength Carbon Steel Tensile Armour Wires
,” Ph.D. dissertation, The University of Manchester, Manchester.11.
Felix-Henry
, A.
, 2007
, “Prevention and Monitoring of Fatigue-Corrosion of Flexible Risers’ Steel Reinforcements
,” 26th International Conference on Offshore Mechanics and Arctic Engineering
, San Diego, CA
, June 10–15
, Vol. 3, pp. 10
–15
.12.
Fagundes
, D. M.
, 2009
, “Numerical-Experimental Evaluation of a Flexible Pipe With a Damaged External Tensile Armor Subjected to Tensile Loading
,” MSc Dissertation in Portuguese, Federal University of Rio de Janeiro, Rio de Janeiro.13.
Liu
, Q.
, Xue
, H.
, Tang
, W.
, and Yuan
, Y.
, 2020
, “Theoretical and Numerical Methods to Predict the Behavior of Unbonded Flexible Riser With Composite Armor Layers Subjected to Axial Tension
,” Ocean Eng.
, 199
, p. 107038
. 14.
Liu
, Q.
, Xue
, H.
, and Tang
, W.
, 2021
, “Behavior of Unbonded Flexible Riser With Composite Armor Layers Under Coupling Loads
,” Ocean Eng.
, 239
, p. 109907
. 15.
Liu
, J.
, Vaz
, M.
, Chen
, R.
, Duan
, M.
, and Hernandez
, I.
, 2020
, “Axial Mechanical Experiments of Unbonded Flexible Pipes
,” Petrol. Sci.
, 17
(5
), pp. 1400
–1410
. 16.
Zhu
, X.
, Lei
, Q.
, Meng
, Y.
, and Cui
, X.
, 2021
, “Analysis of Tensile Response of Flexible Pipe With Ovalization Under Hydrostatic Pressure
,” Appl. Ocean Res.
, 108
, p. 102451
. 17.
Yoo
, D.
, Jang
, B.
, and Yim
, K.
, 2017
, “Nonlinear Finite Element Analysis of Failure Modes and Ultimate Strength of Flexible Pipes
,” Marin. Struct.
, 54
, pp. 50
–72
. 18.
de Sousa
, J. R. M.
, Campello
, G. C.
, Kwietniewski
, C. E. F.
, Ellwanger
, G. B.
, and Strohaecker
, T. R.
, 2014
, “Structural Response of a Flexible Pipe With Damaged Tensile Armor Wires Under Pure Tension
,” Marin. Struct.
, 39
, pp. 1
–38
. 19.
de Sousa
, J. R. M.
, Magluta
, C.
, Roitman
, N.
, and Campello
, G. C.
, 2018
, “On the Extensional-Torsional Response of a Flexible Pipe With Damaged Tensile Armor Wires
,” Ocean Eng.
, 161
, pp. 350
–383
. 20.
Lei
, Q.
, Hou
, Z.
, Zhu
, X.
, and Chen
, C.
, 2024
, “Study on Torsional Response and Ultimate Loading of Unbonded Flexible Risers Under Corrosion Defects
,” Ocean Eng.
, 291
, p. 116413
. 21.
Ji
, G.
, Leira
, B. J.
, Savik
, S.
, Klabo
, F.
, Axelsson
, G.
, and Fergestad
, D.
, 2014
, “Integrity Assessment of Damaged Flexible Pipe Cross-Sections
,” Proceedings of the ASME 2014 33rd International Conference on Offshore and Arctic Engineering
, San Francisco, CA
, June 8–14
, pp. 1
–12
.22.
Ren
, S.
, Tang
, W.
, Kang
, Z.
, and Geng
, H.
, 2020
, “Numerical Study on the Axial-Torsional Response of an Unbonded Flexible Riser With Damaged Tensile Armor Wires
,” Appl. Ocean Res.
, 97
, p. 102045
. 23.
Zhu
, X.
, Lei
, Q.
, Meng
, Y.
, and Cui
, X.
, 2021
, “Tensile Response of a Flexible Pipe With an Incomplete Tensile Armor Layer
,” ASME J. Offshore Mech. Arct. Eng.
, 143
(5
), p. 051702
. 24.
Lei
, Q.
, Chen
, C.
, and Zhu
, X.
, 2023
, “Tensile Failure Behavior of Unbonded Flexible Riser With Damaged Tensile Armor Wires
,” Ocean Eng.
, 2023
(267
), p. 113112
. 25.
Witz
, J. A.
, 1996
, “A Case Study in the Cross-Section Analysis of Flexible Risers
,” Marin. Struct.
, 9
(9
), pp. 885
–904
. 26.
Zhu
, X.
, Lei
, Q.
, Meng
, Y.
, and Cui
, X.
, 2022
, “Calculation Method of Radical Compression Capacity of Carcass Layer of Unbonded Flexible Pipes
,” Acta Petrol. Sin.
, 43
(3
), pp. 410
–419
. 27.
Timoshenko
, S.
, and Woinowsky
, K. S.
, 1959
, Theory of Plates and Shells
, McGraw-Hill
, New York
.28.
Bahtui
, A.
, Bahai
, H.
, and Alfano
, G.
, 2009
, “Numerical and Analytical Modeling of Unbonded Flexible Risers
,” ASME J. Offshore Mech. Arct. Eng.
, 131
(2
), p. 021401
. 29.
Saevik
, S.
, and Berge
, S.
, 1995
, “Fatigue Testing and Theoretical Studies of Two 4 in Flexible Pipes
,” Eng. Struct.
, 17
(4
), pp. 276
–292
. 30.
Bahtui
, A.
, 2008
, “Development of a Constitutive Model to Simulate Unbonded Flexible Riser Pipe Elements
,” Ph.D. dissertation, Brunel University School of Engineering and Design, London.31.
MacKay
, J. R.
, Jiang
, L.
, and Glas
, A. H.
, 2011
, “Accuracy of Nonlinear Finite Element Collapse Predictions for Submarine Pressure Hulls With and Without Artificial Corrosion Damage
,” Marin. Struct.
, 24
(3
), pp. 292
–317
. 32.
Wu
, K.
, and Mosleh
, A.
, 2019
, “Effect of Temporal Variability of Operating Parameters in Corrosion Modelling for Natural Gas Pipelines Subject to Uniform Corrosion
,” J. Nat. Gas Sci. Eng.
, 69
, p. 102930
. Copyright © 2025 by ASME
You do not currently have access to this content.
