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Stelios Kyriakides - One of the best experts on this subject based on the ideXlab platform.
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integral Buckle Arrestors for offshore pipelines enhanced design criteria
International Journal of Mechanical Sciences, 2008Co-Authors: L H Lee, Stelios Kyriakides, Theodoro A NettoAbstract:Abstract Integral Buckle Arrestors are relatively thick wall rings periodically welded in an offshore pipeline at intervals of several hundred meters in order to safeguard the line in case a propagating Buckle initiates. They provide additional circumferential rigidity and thus impede downstream propagation of collapse, limiting the damage to the length of pipe separating the two Arrestors. The effectiveness of such devices was studied parametrically through experiments and numerical simulations in Park and Kyriakides [On the design of integral Buckle Arrestors for offshore pipelines. International Journal of Mechanical Sciences 1997;39(6):643–69]. The experiments involved quasi-static propagation of collapse towards an arrestor, engagement of the arrestor, temporary arrest, and the eventual crossing of collapse to the downstream pipe at a higher pressure. The same processes were simulated with finite element models that included finite deformation plasticity and contact. The experimental crossover pressures enriched with numerically generated values were used to develop an empirical design formula for the arresting efficiency of such devices. A recent experimental extension of this work revealed that for some combinations of arrestor and pipe yield stresses, the design formula was overly conservative. Motivated by this finding, a new broader parametric study of the problem was undertaken, which demonstrated that the difference between the pipe and the arrestor yield stress affects significantly the arrestor performance. The original arrestor design formula was then modified to include the new experimental and numerical results producing an expression with a much wider applicability.
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on the arresting efficiency of slip on Buckle Arrestors for offshore pipelines
International Journal of Mechanical Sciences, 2004Co-Authors: L H Lee, Stelios KyriakidesAbstract:Slip-on Buckle Arrestors are tight-fitting rings placed over the pipe at intervals of several hundred meters. They locally increase the pipe resistance to collapse by providing additional circumferential rigidity, and thus impede downstream propagation of collapse. This type of arrestor offers important advantages over other designs as it does not require welding. Alternatively, when split in two and by the addition of flanges, it can be clamped onto a continuous pipe. This is an essential characteristic for lines installed by the reeling method. It has long been known that such devices often cannot reach higher levels of arresting efficiency. The somewhat deficient performance is due to the fact that a propagating Buckle can penetrate such devices via a folded-up U-mode at pressures that are lower than the collapse pressure of the pipe. Previous work on the subject from the 1970s dealt with relatively thin-walled pipes used in shallow waters. The subject has recently been revisited and bounds for this deficiency in performance have been established. The deficiency depends on the pipe D/t and on the steel grade. This paper presents the results of a more detailed study of such Arrestors for pipes with lower D/t values (18–35) suitable for moderately deep and deep waters. The arresting efficiency has been studied parametrically through experiments and full scale numerical simulations. The results have also shown the previously developed efficiency bounds to be viable. A new empirical design formula has been developed. Used in conjunction with the efficiency bounds, it provides a reliable method for an expanded use of slip-on type Buckle Arrestors in many deepwater applications.
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efficiency limits for slip on type Buckle Arrestors for offshore pipelines
Journal of Engineering Mechanics-asce, 2002Co-Authors: Stelios KyriakidesAbstract:Slip-on Buckle Arrestors for offshore pipelines offer important advantages over other arrestor designs as they do not require welding. An additional advantage offered by the related concept of the two-part clamp-on arrestor is that it can be installed onto a continuous pipe. It has long been known that such devices often cannot reach higher arresting efficiencies. As a result, the use of slip-on Arrestors in deepwater applications has been limited. The somewhat deficient performance is due to the fact that a propagating Buckle can penetrate such devices via a folded-up U mode at pressures that are lower than the collapse pressure of the pipe. This can take place even for very rigid rings. A methodology for generating bounds on the maximum arresting efficiency that can be expected from slip-on Arrestors is developed. An upper bound of their efficiency is related to the pressure at which a propagating Buckle starts to penetrate a long and stiff circumferential confinement. A lower bound is established by relating the crossover pressure to the lowest pressure at which the Buckle will propagate through the confinement. The parametric dependence of both of these pressures was established experimentally. The method developed yields the range of pipe D/t's where degradation in arresting efficiency can be expected and predicts its extent. The arresting efficiency degradation was shown to depend on the yield stress of the pipe. Pipe of higher yield stress exhibits smaller degradation in arresting efficiency.
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dynamic performance of integral Buckle Arrestors for offshore pipelines part i experiments
International Journal of Mechanical Sciences, 2000Co-Authors: Theodoro A Netto, Stelios KyriakidesAbstract:Abstract A design methodology for integral Buckle Arrestors for deepwater pipelines was presented in a previous study (Park TD, and Kyriakides S., International Journal of Mechanical Sciences 1997;39:643–69). It was based on experiments and analyses in which Buckles engaged the Arrestors quasi-statically. In this two-part paper series, the performance of the same Arrestors is reevaluated under the more realistic dynamic Buckle propagation conditions encountered in the sea. The experimental program described in Part I involves tubes with D/t=27.9 and Arrestors with L a /D=0.5 . The quasi-static arresting efficiency of Buckle Arrestors is first established experimentally as a function of the arrestor thickness. The same arrestor designs are then tested again in constant pressure environments where Buckles propagate at velocities of 400–1100 ft/s. Experiments are conducted using both water and air as pressurizing media. A typical test specimen involves a relatively long upstream section of tube welded to an arrestor and to a downstream tube. The Buckle is initiated in the upstream tube, accelerates to steady-state propagation, engages the arrestor and is either arrested or crosses over. For each arrestor design several such tests are required in order to bracket the dynamic crossover pressure. For all cases considered, the dynamic crossover pressure was found to exceed the corresponding quasi-static value. The reasons for this enhancement in performance are discussed in Part II in the light of results from numerical simulations of this process.
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dynamic performance of integral Buckle Arrestors for offshore pipelines part ii analysis
International Journal of Mechanical Sciences, 2000Co-Authors: Theodoro A Netto, Stelios KyriakidesAbstract:Abstract In the second part of this study we present models for simulating the quasi-static and dynamic propagation and arrest of Buckles in pipelines. The models are developed within the framework of the nonlinear finite element ABAQUS and are used to simulate the quasi-static and dynamic arrest experiments in Part I. They are based on finite deformation kinematics and properly treat the contact that develops in the collapsed tube behind the propagating Buckle. In the quasi-static model, the tube and arrestor materials are modeled as J2 flow theory solids with isotropic hardening. In the dynamic model, the rate dependence of SS-304 is assumed to exhibit an overstress power–law dependence. The pressurizing medium is assumed to be vacuum. The dynamic model is shown to reproduce accurately the conditions of steady-state Buckle propagation as well as the dynamic engagement of a Buckle with an arrestor. For Buckle velocities of interest, the Buckle profile was found to have sharpened considerably compared to the quasi-static one. The numerical results showed the same dynamic enhancement of arrestor performance observed in the experiments. When the much sharper dynamic Buckle profile engages an arrestor, it initially induces to it and to the downstream tube significant reverse ovality. This tends to obstruct and delay the flattening of the arrestor and tube which is the cause of the crossing of Arrestors with quasi-static efficiencies of less than 0.7. The net result is that a higher pressure is required to cross the Arrestors when the Buckle is running. As in the experiments, the biggest dynamic enhancement was found to occur for Arrestors of efficiencies in the range of 0.35–0.6. Based on the results of this study it is concluded that quasi-static design procedures for integral Buckle Arrestors proposed previously are conservative.
Theodoro A Netto - One of the best experts on this subject based on the ideXlab platform.
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integral Buckle Arrestors for offshore pipelines enhanced design criteria
International Journal of Mechanical Sciences, 2008Co-Authors: L H Lee, Stelios Kyriakides, Theodoro A NettoAbstract:Abstract Integral Buckle Arrestors are relatively thick wall rings periodically welded in an offshore pipeline at intervals of several hundred meters in order to safeguard the line in case a propagating Buckle initiates. They provide additional circumferential rigidity and thus impede downstream propagation of collapse, limiting the damage to the length of pipe separating the two Arrestors. The effectiveness of such devices was studied parametrically through experiments and numerical simulations in Park and Kyriakides [On the design of integral Buckle Arrestors for offshore pipelines. International Journal of Mechanical Sciences 1997;39(6):643–69]. The experiments involved quasi-static propagation of collapse towards an arrestor, engagement of the arrestor, temporary arrest, and the eventual crossing of collapse to the downstream pipe at a higher pressure. The same processes were simulated with finite element models that included finite deformation plasticity and contact. The experimental crossover pressures enriched with numerically generated values were used to develop an empirical design formula for the arresting efficiency of such devices. A recent experimental extension of this work revealed that for some combinations of arrestor and pipe yield stresses, the design formula was overly conservative. Motivated by this finding, a new broader parametric study of the problem was undertaken, which demonstrated that the difference between the pipe and the arrestor yield stress affects significantly the arrestor performance. The original arrestor design formula was then modified to include the new experimental and numerical results producing an expression with a much wider applicability.
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dynamic performance of integral Buckle Arrestors for offshore pipelines part i experiments
International Journal of Mechanical Sciences, 2000Co-Authors: Theodoro A Netto, Stelios KyriakidesAbstract:Abstract A design methodology for integral Buckle Arrestors for deepwater pipelines was presented in a previous study (Park TD, and Kyriakides S., International Journal of Mechanical Sciences 1997;39:643–69). It was based on experiments and analyses in which Buckles engaged the Arrestors quasi-statically. In this two-part paper series, the performance of the same Arrestors is reevaluated under the more realistic dynamic Buckle propagation conditions encountered in the sea. The experimental program described in Part I involves tubes with D/t=27.9 and Arrestors with L a /D=0.5 . The quasi-static arresting efficiency of Buckle Arrestors is first established experimentally as a function of the arrestor thickness. The same arrestor designs are then tested again in constant pressure environments where Buckles propagate at velocities of 400–1100 ft/s. Experiments are conducted using both water and air as pressurizing media. A typical test specimen involves a relatively long upstream section of tube welded to an arrestor and to a downstream tube. The Buckle is initiated in the upstream tube, accelerates to steady-state propagation, engages the arrestor and is either arrested or crosses over. For each arrestor design several such tests are required in order to bracket the dynamic crossover pressure. For all cases considered, the dynamic crossover pressure was found to exceed the corresponding quasi-static value. The reasons for this enhancement in performance are discussed in Part II in the light of results from numerical simulations of this process.
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dynamic performance of integral Buckle Arrestors for offshore pipelines part ii analysis
International Journal of Mechanical Sciences, 2000Co-Authors: Theodoro A Netto, Stelios KyriakidesAbstract:Abstract In the second part of this study we present models for simulating the quasi-static and dynamic propagation and arrest of Buckles in pipelines. The models are developed within the framework of the nonlinear finite element ABAQUS and are used to simulate the quasi-static and dynamic arrest experiments in Part I. They are based on finite deformation kinematics and properly treat the contact that develops in the collapsed tube behind the propagating Buckle. In the quasi-static model, the tube and arrestor materials are modeled as J2 flow theory solids with isotropic hardening. In the dynamic model, the rate dependence of SS-304 is assumed to exhibit an overstress power–law dependence. The pressurizing medium is assumed to be vacuum. The dynamic model is shown to reproduce accurately the conditions of steady-state Buckle propagation as well as the dynamic engagement of a Buckle with an arrestor. For Buckle velocities of interest, the Buckle profile was found to have sharpened considerably compared to the quasi-static one. The numerical results showed the same dynamic enhancement of arrestor performance observed in the experiments. When the much sharper dynamic Buckle profile engages an arrestor, it initially induces to it and to the downstream tube significant reverse ovality. This tends to obstruct and delay the flattening of the arrestor and tube which is the cause of the crossing of Arrestors with quasi-static efficiencies of less than 0.7. The net result is that a higher pressure is required to cross the Arrestors when the Buckle is running. As in the experiments, the biggest dynamic enhancement was found to occur for Arrestors of efficiencies in the range of 0.35–0.6. Based on the results of this study it is concluded that quasi-static design procedures for integral Buckle Arrestors proposed previously are conservative.
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on the design of integral Buckle Arrestors for offshore pipelines
Applied Ocean Research, 1998Co-Authors: Stelios Kyriakides, T.-d. Park, Theodoro A NettoAbstract:A common method of limiting the extent of damage induced by a propagating Buckle to a deep water pipeline is to periodically install along the line thick rings welded between adjacent strings of the pipe (integral Buckle arrestor). The rings locally increase the resistance to collapse and, when properly designed, arrest an incoming Buckle. The effectiveness of this type of local reinforcement as a Buckle arrestor was studied through a series of full-scale experiments and through a numerical model. The model was first proven to be capable of accurately simulating the quasi-static crossing of such Arrestors by a Buckle and was then used to study the arresting efficiency of this device as a function of the pipe and arrestor geometric and material parameters. This paper briefly summarizes these results which are subsequently used to establish some bounds for the arrestor thickness and length and to develop empirical design formulae for such devices.
L H Lee - One of the best experts on this subject based on the ideXlab platform.
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integral Buckle Arrestors for offshore pipelines enhanced design criteria
International Journal of Mechanical Sciences, 2008Co-Authors: L H Lee, Stelios Kyriakides, Theodoro A NettoAbstract:Abstract Integral Buckle Arrestors are relatively thick wall rings periodically welded in an offshore pipeline at intervals of several hundred meters in order to safeguard the line in case a propagating Buckle initiates. They provide additional circumferential rigidity and thus impede downstream propagation of collapse, limiting the damage to the length of pipe separating the two Arrestors. The effectiveness of such devices was studied parametrically through experiments and numerical simulations in Park and Kyriakides [On the design of integral Buckle Arrestors for offshore pipelines. International Journal of Mechanical Sciences 1997;39(6):643–69]. The experiments involved quasi-static propagation of collapse towards an arrestor, engagement of the arrestor, temporary arrest, and the eventual crossing of collapse to the downstream pipe at a higher pressure. The same processes were simulated with finite element models that included finite deformation plasticity and contact. The experimental crossover pressures enriched with numerically generated values were used to develop an empirical design formula for the arresting efficiency of such devices. A recent experimental extension of this work revealed that for some combinations of arrestor and pipe yield stresses, the design formula was overly conservative. Motivated by this finding, a new broader parametric study of the problem was undertaken, which demonstrated that the difference between the pipe and the arrestor yield stress affects significantly the arrestor performance. The original arrestor design formula was then modified to include the new experimental and numerical results producing an expression with a much wider applicability.
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on the arresting efficiency of slip on Buckle Arrestors for offshore pipelines
International Journal of Mechanical Sciences, 2004Co-Authors: L H Lee, Stelios KyriakidesAbstract:Slip-on Buckle Arrestors are tight-fitting rings placed over the pipe at intervals of several hundred meters. They locally increase the pipe resistance to collapse by providing additional circumferential rigidity, and thus impede downstream propagation of collapse. This type of arrestor offers important advantages over other designs as it does not require welding. Alternatively, when split in two and by the addition of flanges, it can be clamped onto a continuous pipe. This is an essential characteristic for lines installed by the reeling method. It has long been known that such devices often cannot reach higher levels of arresting efficiency. The somewhat deficient performance is due to the fact that a propagating Buckle can penetrate such devices via a folded-up U-mode at pressures that are lower than the collapse pressure of the pipe. Previous work on the subject from the 1970s dealt with relatively thin-walled pipes used in shallow waters. The subject has recently been revisited and bounds for this deficiency in performance have been established. The deficiency depends on the pipe D/t and on the steel grade. This paper presents the results of a more detailed study of such Arrestors for pipes with lower D/t values (18–35) suitable for moderately deep and deep waters. The arresting efficiency has been studied parametrically through experiments and full scale numerical simulations. The results have also shown the previously developed efficiency bounds to be viable. A new empirical design formula has been developed. Used in conjunction with the efficiency bounds, it provides a reliable method for an expanded use of slip-on type Buckle Arrestors in many deepwater applications.
T.-d. Park - One of the best experts on this subject based on the ideXlab platform.
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on the design of integral Buckle Arrestors for offshore pipelines
Applied Ocean Research, 1998Co-Authors: Stelios Kyriakides, T.-d. Park, Theodoro A NettoAbstract:A common method of limiting the extent of damage induced by a propagating Buckle to a deep water pipeline is to periodically install along the line thick rings welded between adjacent strings of the pipe (integral Buckle arrestor). The rings locally increase the resistance to collapse and, when properly designed, arrest an incoming Buckle. The effectiveness of this type of local reinforcement as a Buckle arrestor was studied through a series of full-scale experiments and through a numerical model. The model was first proven to be capable of accurately simulating the quasi-static crossing of such Arrestors by a Buckle and was then used to study the arresting efficiency of this device as a function of the pipe and arrestor geometric and material parameters. This paper briefly summarizes these results which are subsequently used to establish some bounds for the arrestor thickness and length and to develop empirical design formulae for such devices.
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on the performance of integral Buckle Arrestors for offshore pipelines
International Journal of Mechanical Sciences, 1997Co-Authors: T.-d. Park, Stelios KyriakidesAbstract:Abstract This paper presents the results of a study on the effectiveness of integral Buckle Arrestors for offshore pipelines. A series of full scale experiments were conducted where the pressure at which Buckles propagating quasi-statically crossed Arrestors of various lengths and thicknesses was established. The crossover pressures were used to establish the parametric dependence of the arresting efficiency (as defined in Kyriakides and Babcock, ASME Journal of Pressure Vessel Technology102 (1980) and Proceedings of Offshore Technology Conference (1979)) of such devices. Buckles penetrated the arrestor in two modes: the flattening mode, where the arrestor and downstream pipe collapse in the same manner as the incoming Buckle and the flipped mode, where the sense of collapse of the downstream pipe is orthogonal to the incoming Buckle. The mode switch occurred in the neighborhood of efficiency of 0.7. The process of quasi-static engagement of an arrestor by a propagating Buckle, the temporary arrest of the Buckle and the eventual crossing of the arrestor were simulated through a finite element model. The model is based on finite deformation kinematics, incorporates J2-type plasticity with isotropic hardening, and allows for contact of the walls of the collapsed section of pipe upstream of the arrestor. The model was verified by simulating each of the 15 physical experiments conducted using the actual geometric and material characteristics of the test specimens. The crossover pressures of the simulations were within 5% from the measured values and the mode of crossover was predicted correctly as well. The model was subsequently used to extend the experimental parametric study of arrestor efficiency. Some limiting values of the parameters were established from the results and several design recommendations are made.
Hutama, Isha Frandika - One of the best experts on this subject based on the ideXlab platform.
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Analisis Stabilitas Subsea Gas Pipeline Pada Tumpuan MPS (Major Pipeline Suspension) PT. Perusahaan Gas Negara (Persero) Tbk. SBU Transmisi Sumatera – Jawa
2014Co-Authors: Hutama, Isha FrandikaAbstract:MPS (major pipeline suspension) merupakan salah satu alat yang digunakan untuk meretifikasi panjang bentangan bebas pipa. Metode ini digunakan oleh Perusahaan Gas Negara untuk pipa yang berada di jalur Station Labuhan Maringgai – Muara Bekasi. Hal ini dikarenakan pada kilometer (KP) 12 terdapat palung laut sepanjang 225 m dengan kedalaman maksimal 13 m dari seabed. Pada palung laut tersebut kemudian dipasang 4 buah mps dengan jarak yang bervariasi. Dengan pemasangan mps yang bervariasi ini mengakibatkan pipa mengalami span dikarenakan adanya panjang bentangan bebas yang tidak tertumpu. Oleh karena itu pada tugas akhir ini dilakukan analisis panjang bentangan bebas pada tumpuan mps berkenaan dengan dinamik dan statik span beserta tegangan kombinasi yang terjadi. Dari hasil pembahasan didapatkan bahwa bentangan pipa pada tumpuan mps masih memenuhi kriteria untuk dinamik span dan statik span. Pada analisis statik span perlu dipasang Buckle arrestor untuk mencegah perambatan buckling dikarenakan tekanan eksternal melebihi tekanan perambatan. Hal ini dapat mengakibatkan lokal buckling meskipun tekanan eksternal lebih kecil dari tekanan inisiasi. Sementara untuk tegangan kombinasi masih pada batas aman yakni sebesar 4.21 x 108 Pa dengan batas maksimum tegangan ijin sebesar 4.36 x 108 Pa. ==================================================================================================== MPS (major pipeline suspension) is one of the things which is used to decrease freespan of subsea pipeline. This method had been used by Perusahaan Gas Negara for subsea pipeline in Labuhan Maringgai – Muara Bekasi rute. MPS was built at KP 12 because this location was existed trench along 225 m and the depth of trench 13 m from seabed. Then at KP 12 was built 4 mps with variation distance. Although mps had been built, freespan can not be removed. So, this final project would be analize the freespan at the foundation mps for its dynamic and static span criteria, as well as combination stress. The result of analysis was found that freespan at foundation mps fulfill dynamic and static span criteria. The result of static criterion need to be installed Buckle Arrestors to restrain propagation buckling because of pressure higher than the propagation stress criteria. This case could cause local buckling. While the result of combination stress is 4.21 x 108 Pa which is less than the combination stress criteria of 4.36 x 108 Pa
