Lorenzo Marchionni

Pipe Strength and Deformation Capacity: A Novel FE Tool for the Numerical Lab

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.© 2014 ASME

Offshore Pipeline Installation: 3-Dimensional Finite Element Modelling

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.© 2011 ASME

In-Service Buckling Assessment: The Correct Use of Engineering Analysis Tools

There is consensus on the need for in-service buckling analyses to assess the integrity of both flowlines and long distance trunklines subject to HP/HT service condition. The extent of the analyses and supporting survey depends on the severity of the application.In the last two decades, the pipeline industry has gained significant experience in both the design and operation of pipeline systems exposed to global buckling. Actually, the early 90s have been a watershed: before the phenomenon was just known (theoretically), then it was seen...as soon as pipeline integrity management programmes have been introduced in the offshore pipeline industry practices. Although, limited information have been documented in the open literature, now as then.Several efforts have been dedicated to develop design methods and procedures suitable for operating pipeline safely as well as protecting the population, environmental resources and assets. At the beginning, there was a gap to be closed as specific mitigation measures were never designed. Nowadays, thanks to computational progress, it seems that the attention is addressed to face the uncertainties affecting the subject matter but, sometime, leading to overdesign.The scope of the paper is to present aspects of global buckling design analyses that were performed in recent projects with the aim to highlight the challenges and the risks, the accuracy or the limitation of the methods, the feedback and the lesson learnt of real installed pipelines under operating conditions.Copyright

Strength and Deformation Capacity of Corroded Pipes: The Joint Industry Project

Considering the future development for offshore pipelines, moving towards difficult operating condition and deep/ultra-deep water applications, there is the 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 EP• The full-scale laboratory tests on corroded pipes under bending moment dominated load conditions, performed at C-FER facilities, are shown together with the calibrated ABAQUS FE Model;• The results of the ABAQUS FEM parametric study are presented.© 2013 ASME

Controlling Fatigue Damage during Deepwater Installation of Inline Components

AbstractThe exploitation of ultradeepwater fields often implies the use of large-diameter export pipelines. The installation of such large-diameter and long-distance export pipelines is commonly ac...

Effects of Underwater Explosion on Pipeline Integrity

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.Copyright

Metal Loss: Corrosion Defects Qualification and Structural Integrity Assessment

The management of the flow availability in presence of corrosive fluids may considerably impact on CAPEX and OPEX of offshore pipelines. A correct approach starts from the preliminary phases of a project, with the selection of the most appropriate material in relation to the nature of the corrosive fluids and expected degradation mechanisms (i.e. general corrosion, localized or mesa corrosion and pitting). The construction phases include measures that allow meeting welding requirements and safe guarding the integrity of the line-pipe. The operation shall account for the control of process parameters and transported fluid composition.In the upcoming future offshore pipeline and field development projects, challenging operating conditions in deep/ultra-deep waters means that increasingly careful considerations on the effect of metal loss: corrosion leading to local loss of material may cause a potential pipeline failure under the additional effect of functional and environmental loads, in particular the high external pressure and applied bending moment. The assessment of the structural integrity depends on the type and accuracy of available measurements. In presence of corrosion patterns and accordingly to existing standards (DNV RP-F101, ASME B31G, API 579, BS 7910) the assessment might be unduly conservative; further the presence of important combined loads is not fully covered by standard assessment format.The use of FEM numerical lab can help the evaluation of the residual strength and deformation capacity of the pipeline affected by corrosion, leading to a quite-deterministic characterization of pipeline strength capacity at design stage and in operation. Several studies (both theoretical and experimental) available in the open literature faced this issue and their findings support the proposed analysis methodology. Recently full scale tests have been conducted by the relevant Oil & Gas industry companies (such as Statoil and ENI) and the obtained results have been used for the FE Model calibration and validation of corroded pipelines. Herein an application is presented in order to understand and appreciate the proposed methodology performance in corroded pipeline assessment.Copyright

Advanced Analysis and Design Tools for Offshore Pipeline in Operation

In the last thirty years, the attention of the offshore pipeline industry has been strongly focused on submarine pipelines crossing very uneven seabed. New pipelines crossing the uneven seabed of the Mediterranean Sea and of the North Sea and deep water pipelines crossing the uneven continental slope of the Gulf of Mexico are outstanding examples. Pipeline structural integrity may be threaten by large free-spanning sections between rocky peaks and deep depressions that may be coupled with the pipeline propensity to develop lateral/vertical deflection due to severe service conditions (High Pressure/High Temperature). Generally, these scenarios require mitigation measures aiming to control the development of excessive bending moment/deformation by means of Finite Element (FE) Modeling. FE Modeling gives a valuable contribution to the pipeline engineering at identifying a technical and cost effective solution since the early phase of the project. Finite Element (FE) Model approaches, based on standard structural finite element codes available on the market, such as ABAQUS, ADINA, ANSYS etc., are commonly used to analyze the effects of non-linearity, e.g. steel material, soil-pipe interaction and large rotations/displacements. 3-Dimensional FE Models permit to predict the overall pipeline global response under design loads taking into account the expected (during design phase) and/or actual (after measurements gathered during as-built survey campaign) 3-Dimensional pipeline configuration including 3-Dimensional (along and transversal to the pipeline route) bottom roughness, route bends, intervention works for bottom roughness and free-span correction and mitigation measures against HP/HT condition in operation. In this paper: • The design approach for HP/HT pipelines is described; • The main features of the ABAQUS FE Model, developed to predict the behavior of offshore pipelines in operation, are presented; • Two relevant examples of offshore pipelines subject to pressure and temperature conditions are presented with and without mitigation measures.Copyright