Future offshore pipelines development moves towards challenging operating condition and deep/ultra-deep water applications. Understanding the failure mechanisms and quantifying the strength and deformation capacity of pipelines, special components (buckle arrestors, wye, etc.) and in-line structures (in-line sled, in-line valve, in-line tee, etc.) is a need, under installation and operation loads, taking in account different geometrical characteristics and mechanical behaviors. The objective of this paper is to present and discuss recent FEM approaches integrating global and local analyses to evaluate the pipeline response and local effects, respectively. Thanks to this method the results coming from the global FEM analysis (main loads and driving phenomena) are used as input data for local FE Model with the aim to detect stress/strain intensification and other issues due to the local characteristics. In this paper: • The challenges of future deep water offshore pipelines are briefly presented; • The typical loading scenarios for pipelines during installation and operation are discussed; • The PipeONE 2014 tool, developed to facilitate the input/output data sharing between global and local FEM analyses, is presented and fully described in its main characteristics and capabilities; • An example is presented with the aim to understand and to appreciate the PipeONE 2014 functionality in FE modeling.
With the future development of offshore pipelines moving toward difficult operating conditions and deep/ultradeep water applications, there is a need to understand the failure mechanisms and better quantify the strength and deformation capacity of corroded pipelines, considering the relevant failure modes (collapse, local buckling under internal and external pressure, fracture/plastic collapse, etc.). A joint industry project sponsored by ENI Exploration and Production and Statoil has been launched with the objective to quantify and assess the strength and deformation capacity of corroded pipes in the presence of internal overpressure.
Unexploded charges e.g. mines, bombs, torpedoes, etc... are rarely identified at a very early stage of reconnaissance surveys for pipeline route corridors. These ordnances are found during detailed pre-engineering or pre-lay surveys and, sometimes and not surprisingly, during the ordinary surveys performed on the pipeline in service. UXOs represent a hazard for the pipeline as well as for the assets and people involved in the construction phase. An appropriate mitigation plan in areas potentially affected is generally performed, including ordnance removal or mined-area clearance. Large diameter long offshore trunk lines crossing different territorial waters are often exposed to this kind of hazard. As such, pipeline construction and operation call for advanced numerical modelling as unique/valuable tool for providing a quantitative measure of the UXOs related risks. In recent projects the understanding of the underwater explosion process and prediction of damages associated to specific weapon-target engagement are based on the outcome of engineering tools based on finite element modelling. The continuing development of multi-purpose and multi-physics finite element analyses codes facilitates their application, providing sharp and detailed insight into the complex subject of underwater explosive effect and the coupled response of nearby structures. The scope of the structural integrity assessment is to define the minimum distance to be guaranteed between the pipeline and unexploded ordnance to avoid any risk of pipeline damage, as a function of the quantity of explosive. The engineering task of the integrity assessment includes the definition of the relevant conditions for the pipeline whether buried or free spanning, the analysis of the interaction between the gas bubble and shock pressure waves and the cylindrical shape of the pipeline, both as a shell that collapse under a pressure wave and a pipe length that moves laterally and develops bending. The objective is to evaluate the minimum allowable distance of the ordnance from the pipeline, as a function of the explosive quantity and type. In this paper, a series of real cases is presented in order to provide the most relevant parameters characterizing the integrity assessment under the applied load scenario from propagating shock waves. The propagation in water of shock pressure waves induced by the underwater explosion of a spherical charge is performed using finite element modelling, after model verification and validation with respect to the analytical and experimental formulations available in open literature. The outcome from finite element modelling is compared with findings from a simplified model based on modal analysis of the pipe shell – inward bulging and collapse of the pipe section and of the pipe beam – lateral displacement of the impacted stretch and bending at the crest of the buckle.
The future offshore pipeline development projects envisage the installation of medium to large diameter pipelines (16″ to 32″ ND) transporting gas from the deep waters to the shallow water areas. The development of these deep water projects is limited by the feasibility/economics of the construction phase using the J-lay or the S-lay technology. In particular, the S-lay feasibility depends on the applicable tension at the tensioner which is a function of water depth, stinger geometry (length and curvature), and installation criteria. In this paper: – The challenges of future deep water offshore pipelines are briefly presented; – The installation criteria at the overbend, stinger tip and sagbend are discussed; – The ABAQUS FE Model, developed to simulate pipeline installation, is presented together with the pre- and post-processing program put in place; – The results of the developed ABAQUS FE Model are given considering two typical examples of deep water pipelines installed in the S-lay mode.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.