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Volume 4: Pipelines, Risers, and Subsea Systems最新文献

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Prediction of Pressure Drops in Liquid-Liquid Two-Phase Flow Across Circular Channels 液-液两相流通过圆形通道的压降预测
Pub Date : 2021-06-21 DOI: 10.1115/omae2021-62861
Zurwa Khan, R. Tafreshi, Md Ferdous Wahid, A. Retnanto
Mechanistic models are necessary for understanding and predicting the behavior of liquid-liquid flow for multiple pipe dimensions, mixture properties, and flow patterns. In this paper, a mechanistic model is proposed to calculate pressure drop across circular channels for liquid-liquid two-phase flow. The developed model considers several key aspects of liquid-liquid flow, such as mixed and wavy liquid-liquid interfaces and dispersion within each liquid’s layers. Unique identifiers, such as height, turbulence, and dispersion, are calculated for each phase, using an augmented separated flow model and nonlinear optimization. Comparison of the proposed model with experimental data, comprising of multiple inclination angles and flow patterns, shows accurate predictions for a variety of liquid-liquid flow patterns, including double- and triple-layered flow.
机械模型对于理解和预测多种管道尺寸、混合特性和流型的液-液流动行为是必要的。本文提出了一种计算液-液两相流圆形通道压降的力学模型。所建立的模型考虑了液-液流动的几个关键方面,如混合和波浪形液-液界面以及每个液体层内的分散。使用增强型分离流模型和非线性优化,计算每个相的唯一标识符,如高度、湍流和弥散。将该模型与包含多种倾斜角度和流型的实验数据进行比较,结果表明该模型能够准确预测包括双层流和三层流在内的多种液-液流流型。
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引用次数: 4
Topology Optimization Design of Filling Bodies in an Umbilical Based on Moving Morphable Components Theory 基于运动变形分量理论的脐带充填体拓扑优化设计
Pub Date : 2021-06-21 DOI: 10.1115/omae2021-63523
Lifu Wang, Zhixun Yang, Jun Yan, D. Shi, Yandong Mao, Pengcheng Zhu
Umbilical is an indispensable link of offshore oil & gas resource development equipment for underwater production system, which are mainly composed of functional components such as steel tubes, electric cables and optical cables are in a helically wound structure. Filling bodies are required to support these functional components for improving anti-crushing capacity and fatigue life. Filling bodies have a significant impact on the mechanical and physical properties, which triggers the optimization design of filling bodies. However, the complexity of filling body space brings challenge to the optimization design. Moving Morphable Components (MMC) theory is introduced to topological optimization method in complicated filling body space with the objective of mechanical properties. The results show that the optimized filling bodies can effectively reduce structural weight with the same mechanical properties. Numerical models of cross-sections of umbilicals with the optimized filling bodies are constructed, the cross-sectional mechanical properties are compared with that under the initial filling body form, which can fully verify the feasibility and correctness of this optimization design strategy.
脐带缆是水下生产系统中海上油气资源开发设备不可或缺的环节,主要由钢管、电缆、光缆等功能部件呈螺旋缠绕结构构成。填充体需要支撑这些功能部件,以提高抗破碎能力和疲劳寿命。充填体对充填体的力学和物理性能有重要影响,这就引发了充填体的优化设计。然而,填充体空间的复杂性给优化设计带来了挑战。以力学性能为目标,将运动变形分量(MMC)理论引入复杂填充体空间的拓扑优化方法。结果表明:优化后的充填体能在相同力学性能的情况下有效减轻结构重量。建立了优化充填体下脐带缆截面的数值模型,并与初始充填体形式下的脐带缆截面力学性能进行了比较,充分验证了优化设计策略的可行性和正确性。
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引用次数: 0
On the Plastic Bending Responses of Dented Lined Pipe 凹痕内衬管塑性弯曲响应研究
Pub Date : 2021-06-21 DOI: 10.1115/omae2021-64867
Lin Yuan, Jiasheng Zhou, Haowei Liu, Nian-Zhong Chen
Mechanically lined pipe, which was proven to be cost-effective in transporting corrosive hydrocarbons, has been used in many offshore applications. However, one weakness of this product is that the liner is extremely sensitive to geometric imperfections and can wrinkle and collapse under severe loading. As typical damage of the pipeline, the local dent of the lined pipe involves the deformation of both the carrier pipe and the liner, which poses a severe threat to the integrity of the composite structure. In this paper, we developed a numerical framework to study the responses of the lined pipe during indentation and, more importantly, the influence of local dents on the bending capacity of lined pipes. A slight separation between the liner and the carrier pipe was observed during the indentation, depending on the indenter’s geometric feature. Under bending, the liner typically collapsed earlier than the carrier pipe, causing a considerable reduction of the critical curvature and ultimate load-carrying capacity. The evolution of the deformation of the composite structure during the bending process is presented in this paper. Parametric investigations of some vital variables of the problem were also performed to study their influence on the behavior under indentation and the bending capacity of the composite structure.
机械衬管被证明在输送腐蚀性碳氢化合物方面具有成本效益,已在许多海上应用中得到应用。然而,这种产品的一个缺点是衬垫对几何缺陷非常敏感,在严重的载荷下会起皱和崩溃。内衬管道局部凹陷是管道的一种典型损伤,它涉及到载体管和衬管的变形,对复合材料结构的完整性构成严重威胁。在本文中,我们建立了一个数值框架来研究内衬管在压痕过程中的响应,更重要的是,局部压痕对内衬管弯曲能力的影响。根据压头的几何特征,在压痕过程中观察到衬管和载体管之间有轻微的分离。在弯曲作用下,尾管通常比承载管更早坍塌,导致临界曲率和极限承载能力大幅降低。本文介绍了复合材料结构在弯曲过程中变形的演变过程。对问题的一些关键变量进行了参数化研究,研究了它们对复合材料结构的压痕行为和弯曲能力的影响。
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引用次数: 1
Full Scale Axial, Bending and Torsion Stiffness Tests of a Three Core HVAC Submarine Cable 三芯HVAC海底电缆的全尺寸轴向、弯曲和扭转刚度试验
Pub Date : 2021-06-21 DOI: 10.1115/omae2021-63238
Panagiotis Delizisis, I. Dolianitis, D. Chatzipetros, Vasileios Kanas, G. Georgallis, Konstantinos Tastavridis, Antonios Stamelos, Efstratios Angelis
Submarine, export cables behave, to some point, as long, flexible cylindrical bodies. Their mechanical performance is crucial during laying and operating processes, which depends to a large extent on their stiffness. Although theoretical methods, used to estimate cable stiffness, are currently available, it is difficult to account for the various physical mechanisms involved, such as internal friction, residual torsion and ‘relaxation’ effects. These mechanisms are expected to affect cable stiffness and should be included some way. To represent more realistically cable stiffness, full-scale tests are performed in this paper. The deviation between theoretical and experimental values appears to be significant in certain cases: hence, non-realistic values for cable stiffness would occur if the stiffness estimation relied only on the theoretical methods. Interesting results, affording an in more depth insight and allowing for a better understanding of the cable mechanical performance, are presented in this paper.
在某种程度上,海底出口电缆表现为长而灵活的圆柱体。在铺设和操作过程中,其力学性能至关重要,这在很大程度上取决于其刚度。虽然目前可以使用理论方法来估计缆索的刚度,但很难解释所涉及的各种物理机制,如内摩擦、残余扭转和“松弛”效应。这些机制预计会影响电缆的刚度,应该以某种方式包括在内。为了更真实地反映索刚度,本文进行了全尺寸试验。在某些情况下,理论和实验值之间的偏差似乎是显著的:因此,如果刚度估计仅依赖于理论方法,则会出现不现实的索刚度值。有趣的结果,提供了一个更深入的见解,并允许更好地理解电缆的机械性能,在本文中提出。
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引用次数: 1
Simplified Stochastic Modelling of the Force on a Pipe Bend Due to Two-Phase Slug Flow 两相段塞流作用下弯管受力的简化随机模型
Pub Date : 2021-06-21 DOI: 10.1115/omae2021-62951
Arnout M. Klinkenberg, A. Tijsseling
Slug flow, a flow pattern with alternating aerated liquid pockets (slugs) and large gas bubbles, is a commonly observed flow pattern in oil and gas pipelines. Due to its unsteady character, the force on a pipe bend is fluctuating which results in unacceptable motions when the piping is insufficiently supported. To investigate the risk of fatigue failure of the system, finite-element models are used to predict the dynamic stresses required to estimate the fatigue life of the system. The excitation force of the slug flow is the essential input required for accurate fatigue damage predictions. A new, simplified model of slug forces on a bend is proposed. The model is calculating the slug force by solving the momentum balance over the pipe bend using slug flow properties as liquid holdup and phase velocities. Average properties predicted by a unit slug model cannot predict the stochastic force variations caused by the slug flow. The new approach introduces the stochastic character of slug flow in the force calculations via a log-normal slug length distribution. A Lagrangian slug tracking method is used to solve the governing equations. The modelled liquid holdup, pressure and predicted forces are compared with available measurements and Computational Fluid Dynamics calculations. The measurements were done under atmospheric conditions and the fluids used were air and water. Whether these measurements are representative for high-pressure oil and gas slug flow is unknown. By using a mechanistic approach where the main equations are based on physical laws instead of fitted measured data, the model is applicable for different fluids and operational conditions. To validate the model for oil and gas flows, the results are compared with Computational Fluid Dynamics calculations done with high gas density and typical oil viscosity.
段塞流是油气管道中常见的一种流型,是一种由充气液体袋(段塞)和大气泡交替形成的流型。由于管道的非定常特性,当管道没有得到充分的支撑时,作用在管道弯头上的力是波动的,从而导致无法接受的运动。为了研究系统的疲劳失效风险,采用有限元模型来预测系统疲劳寿命所需的动应力。段塞流的激励力是准确预测疲劳损伤所需的基本输入。提出了一种新的、简化的弯曲段塞力模型。该模型利用段塞流特性(含液率和相速度)求解管弯处的动量平衡,从而计算段塞力。由单元段塞流模型预测的平均性质不能预测由段塞流引起的随机力变化。该方法将段塞流的随机特性引入对数正态段塞长度分布的力计算中。采用拉格朗日段塞跟踪法求解控制方程。模拟的含液率、压力和预测力与现有的测量结果和计算流体动力学计算结果进行了比较。测量是在大气条件下进行的,所用的流体是空气和水。这些测量结果是否能代表高压油气段塞流尚不清楚。该模型采用力学方法,其中主要方程基于物理定律,而不是基于拟合的测量数据,因此适用于不同的流体和操作条件。为了验证油气流动模型,将结果与高气体密度和典型油粘度下的计算流体动力学计算结果进行了比较。
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引用次数: 0
Investigation of Near-Field Temperature Distribution in Buried Dense Phase CO2 Pipelines 埋地致密相CO2管道近场温度分布研究
Pub Date : 2021-06-21 DOI: 10.1115/omae2021-65310
Babafemi Olugunwa, J. Race, A. Yurtseven, T. Tezdogan
Buried pipelines transporting dense phase Carbon dioxide CO2 are crucial to carbon reduction and climate change mitigating technologies such as Carbon Capture and Storage (CCS) and Carbon Capture Utilization and Storage (CCUS). One of the major challenges for optimum pipeline operating conditions is to avoid phase change of the compressed CO2 and maintain temperature and pressure above the critical point throughout the pipeline route. A suitable pipe-soil heat transfer model during design can mitigate this challenge. However, variations in annual ambient temperatures, ground temperature at pipeline burial depth and soil temperature profile behaviors with seasonal climatic conditions especially during winter and summer periods also affect the heat transfer process between the soil burial medium and the CO2 pipeline. Assuming steady state, this paper investigates the nearfield temperature distribution up to 3m lateral distance away from a buried dense phase CO2 pipeline by numerical simulation with a two-dimensional pipe-soil heat transfer model at a burial depth of 2.3m to pipe center using a finite volume computational code. Results show that thermal parameters such as thermal conductivity and the soil temperature profile influence the heat exchange between pipe walls and porous soil medium. Consequently, this study shows that the near-field temperature distribution and effect of heat around a buried CO2 pipeline diminishes with distance and burial depth further away within the immediate vicinity of the pipeline.
输送致密相二氧化碳的埋地管道对于碳捕集与封存(CCS)和碳捕集利用与封存(CCUS)等碳减排和减缓气候变化技术至关重要。优化管道运行条件的主要挑战之一是避免压缩CO2的相变,并在整个管道路线中保持温度和压力高于临界点。在设计中采用合适的管道-土壤传热模型可以缓解这一挑战。然而,年环境温度、管道埋深处地温以及土壤温度剖面随季节气候条件的变化,尤其是冬夏两季,也会影响土壤埋埋介质与CO2管道之间的换热过程。在稳态条件下,采用有限体积计算程序,建立埋深为2.3m的管道-土壤二维传热模型,对埋深为2.3m的致密相CO2管道近场温度分布进行了数值模拟。结果表明,导热系数和土壤温度分布等热参数对多孔土壤介质与管壁之间的热交换有影响。因此,本研究表明,埋地CO2管道附近的近场温度分布和热量效应随着距离和埋深的增加而减小。
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引用次数: 0
Integrity Monitoring of Offshore Arctic Pipelines 北极近海管道完整性监测
Pub Date : 2021-06-21 DOI: 10.1115/omae2021-64174
Todd G. Cowin, G. Lanan, M. Paulin, D. Degeer
For safe and cost-efficient operations of new and existing offshore Arctic pipelines, monitoring of pipeline structural integrity is imperative. A well-founded pipeline integrity management program can optimize production output, extend the life of the pipeline, and serve as a tool for providing preventative maintenance information. Without the implementation of a routine integrity monitoring campaign, pipeline integrity degradation may go undetected until the point of failure. Arctic-specific offshore pipeline design and operational challenges, such as strudel scour, seabed ice gouge, pipeline upheaval buckling, permafrost thaw settlement, and remote location increase the risk and severity of a loss of pipeline integrity. These design cases can create abnormal conditions and ground deformations along sections of the pipeline which can be difficult to immediately detect through standard integrity monitoring systems and schedules. Many of the existing offshore pipelines in the Arctic are buried in remote locations under seasonal ice cover and the failure to detect pipeline damage in a timely manner could have severe safety, environmental, and economic consequences. An Arctic pipeline integrity monitoring philosophy can be implemented to provide further mitigation against loss of pipeline structural integrity by means of regular bathymetry surveys, In-Line Inspection (ILI) campaigns and Fiber Optic Cable (FOC) monitoring. This paper provides a guideline for buried offshore Arctic pipeline integrity monitoring. The guideline covers pipeline integrity assurance incorporated into the pipeline design, the surveys to be completed during installation, as-built assessment of the pipeline profile, the warm-up assessment/implementation needed before start-up, and the integrity inspections to be completed during operations.
为了安全和经济高效地运行新的和现有的北极海上管道,监测管道结构的完整性是必不可少的。一个完善的管道完整性管理程序可以优化生产产出,延长管道的使用寿命,并作为提供预防性维护信息的工具。如果没有实施常规的完整性监测活动,管道完整性的退化可能直到故障点才被发现。北极特定的海上管道设计和运营挑战,如结构冲刷、海底冰泥、管道隆起屈曲、永久冻土融化沉降和偏远位置,增加了管道完整性损失的风险和严重程度。这些设计案例可能会造成管道部分的异常情况和地面变形,而这些情况很难通过标准的完整性监测系统和时间表立即检测到。北极地区现有的许多海上管道都埋在季节性冰盖下的偏远地区,如果不能及时发现管道损坏,可能会造成严重的安全、环境和经济后果。可以实施北极管道完整性监测理念,通过定期测深测量、在线检查(ILI)活动和光纤电缆(FOC)监测,进一步缓解管道结构完整性的损失。本文为北极海上埋地管道完整性监测提供了指导。该指导方针涵盖了管道设计中的完整性保证、安装过程中需要完成的调查、管道外形的竣工评估、启动前需要的预热评估/实施,以及运行过程中需要完成的完整性检查。
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引用次数: 0
A New Transient Thermal Model for Predicting Cooling Temperature and Cooldown Time of a Subsea Pipe-in-Pipe Flowline System Transporting Waxy Hydrocarbons 用于预测输油管系统冷却温度和冷却时间的新瞬态热模型
Pub Date : 2021-06-21 DOI: 10.1115/omae2021-64866
K. Shukla
The proper understanding of cooling temperature and cooldown time for the operation of a subsea system producing hydrocarbons from the reservoir to the host facility is one of the important flow assurance issues for managing heat retention in the production system due to solids formation and their deposition. In this paper, an analytical transient thermal model is developed for determining the cooling temperature and cooldown time for shut-in operations of a subsea pipe-in-pipe production system, transporting waxy crude oil from the reservoir to the host facility. Here, the cooldown time is defined as the time when the fluid temperature approaches the wax appearance temperature before reaching the hydrate formation temperature during any shut-in operations. The analytical model builds upon an inhomogeneous transient method incorporating an internal temperature gradient. The model results are benchmarked against the commercial OLGA simulation results for a few selected deepwater pipe-in-pipe flowline configuration. The model predictions resemble well with OLGA results over a range of conditions. The analytical model could optimize dry insulation and cooldown time requirements efficiently for the assumed PIP flowline configurations and fluid properties under any subsea environments.
对于从油藏到主机设备生产碳氢化合物的海底系统来说,正确理解冷却温度和冷却时间是管理由于固体形成和沉积而导致的生产系统热保留的重要流动保证问题之一。本文建立了一个分析的瞬态热模型,用于确定海底管中管生产系统关井作业的冷却温度和冷却时间,该系统将含蜡原油从油藏输送到主机设施。这里的冷却时间定义为在任何关井作业中,流体温度接近蜡样温度,然后达到水合物形成温度的时间。该分析模型建立在包含内部温度梯度的非均匀瞬态方法之上。模型结果与商业OLGA模拟结果进行了基准测试,用于几种选定的深水管中管管线配置。在一系列条件下,模型预测与OLGA结果非常相似。该分析模型可以有效地优化任何海底环境下假定的PIP管线配置和流体性质的干绝缘和冷却时间要求。
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引用次数: 0
A Review of DNVGL-RP-F105 Fatigue Assessment Model or Why My Free Span Has Not Failed DNVGL-RP-F105疲劳评估模型综述&“为什么我的自由跨度没有失效
Pub Date : 2021-06-21 DOI: 10.1115/omae2021-63747
Mario Caruso
The objective of a free span fatigue assessment is to provide a rational criterion to evaluate the long-term integrity of a free spanning pipeline, to which DNVGL-RP-F105 was developed. The Recommended Practice has a long history. Guideline 14, the foundation document to it, was released in 1998. The guidelines of the DNVGL-RP-F105 were gradually adopted by the industry for free spans analysis, and even API 1111 makes direct reference to it. Today, DNVGL-RP-F105 is the de facto Vortex Induced Vibration analysis guide for all applications where small number of bending driven modes are expected to be excited, overstepping its original purpose of free spanning pipelines and providing guidance when no other source exists. With such a long history, it is easy to forget the basis for the Recommended Practice fatigue model and obtain results that do not match expectations. A prime example is when assessing a free span based on survey and the fatigue life capacity calculated following the Recommended Practice is much smaller than the actual exposure time. In this situation one may ask “why my free span has not failed?” and conclude that the Recommended Practice is either too over conservative or plainly wrong. This paper reviews some key aspects of the DNVGL-RP-F105 fatigue model and explore their implication to fatigue design and assessment. And it hopes to clarify why your free span has not failed even when you expected it to.
自由跨疲劳评估的目的是为评估自由跨管道的长期完整性提供一个合理的标准,DNVGL-RP-F105就是为此而开发的。推荐实践有很长的历史。准则14,它的基础文件,于1998年发布。DNVGL-RP-F105的指导原则逐渐被业界采用,甚至API 1111也直接参考了它。如今,DNVGL-RP-F105实际上是旋涡诱导振动分析的指南,适用于所有希望激发少量弯曲驱动模式的应用,超越了其自由跨越管道的原始目的,并在没有其他源存在的情况下提供指导。有了这么长的历史,很容易忘记推荐实践疲劳模型的基础,并获得与预期不匹配的结果。一个典型的例子是,当根据调查评估自由跨度时,根据推荐实践计算的疲劳寿命容量远远小于实际暴露时间。在这种情况下,人们可能会问“为什么我的自由跨度没有失效?”,并得出结论:“推荐做法”要么过于保守,要么明显是错误的。本文综述了DNVGL-RP-F105疲劳模型的一些关键方面,并探讨了它们对疲劳设计和评估的意义。它还希望澄清为什么即使在您预期的情况下,您的自由跨度也没有失效。
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引用次数: 0
Tangguh Project: In-Service Buckling Design of Offshore Pipelines With Major Uncertainties on Soil Characterization and Seabed Mobility 唐古项目:考虑土壤特性和海底流动性等主要不确定性因素的海上管道在役屈曲设计
Pub Date : 2021-06-21 DOI: 10.1115/omae2021-62361
S. Bughi, Luigi Foschi, Lorenzo Marchionni, R. Vichi, Yansa Zulkarnain
This paper is based on the experience made during the design and installation of an offshore pipeline recently completed in Indonesia, where a 24” subsea production pipeline (16km long in 70m water depth) was found susceptible during design to lateral buckling. Buckling is a well understood phenomenon. However, this project was characterized by major uncertainties mainly driven by soil characterization, soil zonation, soil-pipe interaction, seabed mobility and seabed liquefaction. These uncertainties have played a key role in the in-service buckling design. In particular, extreme pipeline embedment scenarios ranging from fully exposed to fully covered (due to natural sand transportation) were accounted with a significant impact on soil-pipe interaction. To limit the development of excessive strain within the acceptance criteria, a mitigation strategy based on interacting planned buckles has been adopted installing three Buckle Initiators (BI) along the pipeline route. During design great efforts have been spent with the aim to demonstrate the robustness of the proposed solution. 3-D FEM simulations with ABAQUS have been performed taking into account the pipeline route including route curves and the sea bottom profile and the buckle initiators with their main geometries. All uncertainties have been considered following a deterministic approach. The impact of environmental and accidental loads due to a potential trawl-gear interaction were assessed as well. The pipeline susceptibility to lateral and/or upheaval buckling along the sandwave areas has been analyzed as well in order to evaluate the need of mitigation measures suitable to freeze the pipeline configuration during the operating life. Finally, once the lateral buckling design philosophy was established, the cyclic expansion and walking behavior of the pipeline were assessed to verify the pipeline structural integrity at buckles, route curve pull-out and the accumulative pipeline expansion at spools. This paper presents all main engineering aspects faced during design and first feedbacks from field after the pipeline installation.
本文基于最近在印度尼西亚完成的一条海上管道的设计和安装过程中的经验,该管道在设计过程中发现一条24英寸海底生产管道(长16公里,水深70米)容易发生侧向屈曲。屈曲是一种众所周知的现象。然而,该项目具有主要不确定性,主要受土壤特性、土壤区带性、土壤-管道相互作用、海底流动性和海底液化的影响。这些不确定性对在役屈曲设计起到了关键作用。特别是,从完全暴露到完全覆盖(由于自然输沙)的极端管道埋置场景对土-管相互作用产生了重大影响。为了在验收标准范围内限制过度应变的发展,采用了一种基于相互作用的计划屈曲的缓解策略,在管道路线沿线安装了三个屈曲启动器(BI)。在设计过程中,为了证明所提出的解决方案的鲁棒性,已经付出了巨大的努力。利用ABAQUS软件进行了三维有限元模拟,考虑了管道的路线曲线和海底剖面,以及扣环起爆器的主要几何形状。所有的不确定性都是按照确定性方法来考虑的。由于潜在的拖网渔具相互作用,环境和意外载荷的影响也进行了评估。此外,还分析了沿沙波区域的管道对横向和/或剧变屈曲的敏感性,以评估在使用寿命期间采取适当的缓解措施以冻结管道配置的必要性。最后,在建立横向屈曲设计理念后,评估管道的循环膨胀和行走行为,以验证管道在屈曲处的结构完整性,路线曲线拉出和管道在阀芯处的累积膨胀。本文介绍了管道设计过程中面临的主要工程问题和管道安装后现场的初步反馈。
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引用次数: 0
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Volume 4: Pipelines, Risers, and Subsea Systems
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