Structural integrity of offshore pipelines considering buckling and fracture limit-states

2021 ◽  
pp. 697-703
Author(s):  
M. Kaveh ◽  
C. Guedes Soares
Keyword(s):  
Structural Integrity ◽  
Limit States ◽  
Offshore Pipelines

Evaluation of the Effect of Yield to Tensile (Y/T) Ratio on the Structural Integrity of Offshore Pipeline by Limit State Design Approach

2006 ◽  
Author(s):  
Gianluca Mannucci ◽  
Giuliano Malatesta ◽  
Giuseppe Demofonti ◽  
Marco Tivelli ◽  
Hector Quintanilla ◽  
...  
Keyword(s):  
Structural Reliability ◽  
Failure Modes ◽  
Structural Integrity ◽  
Limit State ◽  
Minor Effect ◽  
Offshore Pipelines ◽  
Limit State Design ◽  
A Minor ◽  
Probabilistic Failure Analysis ◽  
Failure Probabilities

Nowadays specifications require strict Yield to Tensile ratio limitation, nevertheless a fully accepted engineering assessment of its influence on pipeline integrity is still lacking. Probabilistic analysis based on structural reliability approach (Limit State Design, LSD) aimed at quantifying the yield to tensile strength ratio (Y/T) influence on failure probabilities of offshore pipelines was made. In particular, Tenaris seamless pipe data were used as input for the probabilistic failure analysis. The LSD approach has been applied to two actual deepwater design cases that have been on purpose selected, and the most relevant failure modes have been considered. Main result of the work is that the quantitative effect of the Y/T ratio on failure probabilities of a deepwater pipeline resulted not so big as expected; it has a minor effect, especially when Y only governs failure modes.

scholarly journals Integrity Management of Marine Structures; With Emphasis on Design for Structural Robustness

2018 ◽  
Author(s):  
Torgeir Moan
Keyword(s):  
Structural Damage ◽  
Structural Integrity ◽  
Oil And Gas ◽  
Offshore Structures ◽  
Design Standards ◽  
Limit States ◽  
Fabrication Errors ◽  
Integrity Management ◽  
Operational Errors ◽  
And Control

Based on relevant accident experiences with oil and gas platforms, a brief overview of structural integrity management of offshore structures is given; including an account of adequate design criteria, inspection, repair and maintenance as well as quality assurance and control of the engineering processes. The focus is on developing research based design standards for Accidental Collapse Limit States to ensure robustness or damage tolerance in view damage caused by accidental loads due to operational errors and to some extent abnormal structural damage due to fabrication errors. Moreover, it is suggested to provide robustness in cases where the structural performance is sensitive to uncertain parameters. The use of risk assessment to aid decisions in lieu of uncertainties affecting the performance of novel and existing offshore structures, is briefly addressed.

On Determination of Acceptable Safety Class in Design of Pipe-In-Pipe (PIP) Systems

2014 ◽  
Author(s):  
Soheil Manouchehri ◽  
Guillaume Hardouin ◽  
David Kaye ◽  
Jason Potter
Keyword(s):  
Failure Modes ◽  
Structural Integrity ◽  
Oil And Gas ◽  
Gas Production ◽  
Point Of View ◽  
Insulation Material ◽  
Limit States ◽  
Oil And Gas Production ◽  
Operational Conditions ◽  
Outer Pipe

Pipe-In-Pipe (PIP) systems are increasingly used in subsea oil and gas production where a low Overall Heat Transfer Coefficient (OHTC) is required. A PIP system is primarily composed of an insulated inner pipe which carries the production fluid and an outer pipe that protects the insulation material from the seawater environment. This provides a dry environment within the annulus and therefore allows the use of high quality dry insulation system. In addition, from a safety point of view, it provides additional structural integrity and a protective barrier which safeguards the pipeline from loss of containment to the environment. Genesis has designed a number of PIP systems in accordance with the recognized subsea pipeline design codes including DNV-OS-F101 [1]. In section 13 F100 of the 2013 revision, a short section has been included in which PIP systems are discussed and overall design requirements for such systems are provided. It has also been stated that the inner and outer pipes need to have the same Safety Class (SC) unless it can be documented otherwise. This paper looks at the selection of appropriate SC for the outer pipe in a design of PIP systems based on an assessment of different limit states, associated failure modes and consequences. Firstly, the fundamentals of selecting an acceptable SC for a PIP system are discussed. Then, different limit states and most probable failure modes that might occur under operational conditions are examined (in accordance with the requirements of [1]) and conclusions are presented and discussed. It is concluded that the SC of the outer pipe of a PIP system may be lower than that of the inner pipe, depending on the failure mode and approach adopted by the designer.

Structural analysis of old stone arch bridges

1989 ◽  
Vol 16 (6) ◽  
pp. 789-797 ◽  
Author(s):  
D. K. McNeely ◽  
G. C. Archer ◽  
K. N. Smith
Keyword(s):  
Structural Analysis ◽  
Structural Integrity ◽  
Load Capacity ◽  
Structural Response ◽  
Secondary Effects ◽  
Structural Behaviour ◽  
Limit States ◽  
Significant Deterioration ◽  
Arch Bridges ◽  
Stone Arches

The use of stone arches for bridge construction has generally ceased, but since these structures still exist in modern road systems, their structural integrity is of current concern. This paper presents an analysis technique suited for the thick jointed heritage stone arch bridges found in Canada. The effect of increased mortar joint size on structural response is investigated. The response of a section to eccentric thrust is postulated and the effective section properties are derived. Structural behaviour proceeds from a fixed arch to a two-hinge, a three-hinge, and finally a five-hinge failure mode for a symmetrical arch with midspan loading. A typical load–deflection curve is developed, suitably adjusted for secondary effects due to changes in geometry and material nonlinearity. Stone arch bridges in Canada were constructed with thick mortar joints, which exhibit significant deterioration of stiffness with load eccentricity and, therefore, significant secondary effects; as thickness increases, ultimate strength decreases. A suitable limit states prediction for the load capacity of old stone arches is proposed. Key words: arch, bridge, heritage, limit states, stone, structural analysis.

scholarly journals Incremental Dynamic Analysis for Estimating Seismic Performance of Multi-Story Buildings with Butterfly-Shaped Structural Dampers

Buildings ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 78 ◽  
Author(s):  
Alireza Farzampour ◽  
Iman Mansouri ◽  
Hamzeh Dehghani
Keyword(s):  
Dynamic Analysis ◽  
Seismic Performance ◽  
Structural Integrity ◽  
Specific Area ◽  
Load Resistance ◽  
Incremental Dynamic Analysis ◽  
Seismic Loads ◽  
Limit States ◽  
Braced Frame ◽  
Collapse Behavior

Structural strength and stiffness were previously investigated to sufficiently improve the lateral load resistance against major events. Many buildings require appropriate design to effectively withstand the lateral seismic loads and reduce the corresponding damages. Design methodologies and structural elements were recently introduced to improve the energy dissipation capability and limit the high force demands under seismic loadings. The new systems are designed to protect the structural integrity and concentrate the inelasticity in a specific area, while the remaining parts are kept undamaged and intact. This study introduces a new structural system with dampers having strategic cutouts, leaving butterfly-shaped shear dampers for dominating the yielding mechanism over other brittle limit states. The new system is designed for re-establishing the conventional eccentrically braced frame system with simple linking beams. The system with strategic cutouts is subsequently used and compared with the eccentrically braced frames (EBF) system for seismic performance investigation and incremental dynamic analysis (IDA), using the OpenSees program, which is used to indicate the collapse behavior under forty-four selected ground motions. Results show that the butterfly-shaped multi-story buildings, compared to the corresponding conventional systems, are capable of enhancing the system resistance against lateral seismic loads by postponing the collapse state to the larger drift ratio values.

scholarly journals Mechanical Modeling of the Polymeric Coating on a Subsea Pipeline

2019 ◽  
Author(s):  
Ole Vestrum ◽  
Magnus Langseth ◽  
Tore Børvik
Keyword(s):  
Structural Integrity ◽  
Mechanical Response ◽  
Mechanical Design ◽  
Design Guidelines ◽  
Polymeric Coating ◽  
Polymeric Coatings ◽  
Micro Computed Tomography ◽  
Offshore Pipelines ◽  
Subsea Pipeline ◽  
Beneficial Effects

Abstract Offshore pipelines may be exposed to a range of extreme loading situations during operation on the seabed such as impact by trawl gear or anchors. While not primarily being designed for it, thermal insulating polymeric coatings are experienced to provide beneficial contributions to the structural integrity of subsea pipeline designs. In recent editions, the prevailing standards and design guidelines are allowing for the inclusion of external coating products in the mechanical design evaluation. This secondary functionality of insulating coatings presents a great potential in terms of more optimized pipeline designs. However, due to the lack of reliable and versatile mechanical models, any beneficial effects from these complex polymeric insulating coatings are often omitted in simulations. This work presents a finite element based approach for assessing the mechanical response of polymeric coatings on offshore pipelines with different porous structures imaged using X-ray micro computed tomography. The modeling approach is also compared with experimental results.

Integrity Management of Offshore Structures With Emphasis on Design for Structural Damage Tolerance

2020 ◽  
Vol 142 (3) ◽  
Author(s):  
Torgeir Moan
Keyword(s):  
Structural Damage ◽  
Structural Integrity ◽  
Oil And Gas ◽  
Damage Tolerance ◽  
Progressive Failure ◽  
Offshore Structures ◽  
Limit States ◽  
Safety Level ◽  
Integrity Management ◽  
Conservative Values

Abstract Based on relevant accident experiences with oil and gas platforms, structural integrity management of offshore structures is briefly outlined, including adequate design criteria, fabrication and operational procedures, as well as life cycle quality assurance and control. The focus is on developing an operational design standard for accidental collapse limit states to ensure robustness or damage tolerance. The focus is to ensure an acceptable safety level against progressive failure leading to total loss in view of initial damage caused by accidental actions due to operational errors and abnormal structural damage due to fabrication errors and abnormal deterioration during operation as well as the actions on the damaged structure and inherent uncertainties. Moreover, the damage tolerance required for achieving safety by inspection, monitoring and repair strategies, is briefly addressed. While the basic damage tolerance requirement refers to the survival of the structure in certain damage conditions, wider aspects of robustness in terms of the structure’s sensitivity to the deviation of action effects and resistances from normal conditions are also briefly addressed. In particular, it is suggested to provide robustness in cases where the structural performance is sensitive to uncertain parameters, by choosing conservative values of these parameters.

Structural Integrity Assessment of a Pipeline Subjected to an Underwater Explosion

2011 ◽  
Author(s):  
Paolo Monti ◽  
Caterina Molinari ◽  
Massimiliano Bocciarelli ◽  
Alberto Corigliano ◽  
Stefano Mariani
Keyword(s):  
Structural Integrity ◽  
Underwater Explosion ◽  
Structural Response ◽  
Potential Hazard ◽  
Limit States ◽  
Integrity Assessment ◽  
Definition Of ◽  
Bubble Pulsation ◽  
Numerical Approaches

Several trunklines cross either areas which in the recent past were war theatre or dumping areas used for burying weapons after the last war. The presence of unexploded mines, bombs or torpedoes on the seabed constitutes a potential hazard for the structural integrity of submarine pipelines. Before laying, it is therefore necessary to remove the unexploded charges within a corridor including the route. Risk still remains during the pipeline life, since annual surveys can show evidences of unexploded mines or torpedoes dragged by fishing gears till the protruding pipeline. Consequently, the structural integrity assessment of a submarine pipeline subjected to underwater explosions is of the utmost importance. The aforementioned assessment involves several aspects: the characterization of shock wave and gas bubble pulsation in water; the definition of loading conditions on the pipeline; the characterisation of the strain-rate properties of the steel; the local and global structural analysis; the pipe verification criteria. Aim of this study is to describe how the aforementioned aspects can be managed. Analytical and numerical approaches concerning the assessment of the structural response of the pipeline are presented, and criteria for Serviceability and Accidental Limit States are proposed.

Structural integrity of a welded attachment junction: Analysis and collapse tests

2000 ◽  
Vol 35 (6) ◽  
pp. 567-580 ◽  
Author(s):  
T G F Gray ◽  
D Mackenzie ◽  
A Heaton ◽  
A Lubis
Keyword(s):  
Structural Integrity ◽  
Limit State ◽  
Strength Properties ◽  
Limit States ◽  
Element Analysis ◽  
Design Assessment ◽  
Linear Elastic ◽  
Codes Of Practice ◽  
Load Carrying ◽  
Failure Conditions

The aim of the research described was to establish a sound structural analysis procedure for load-carrying fillet-welded attachments with particular reference to cases where the welds are well separated by crack-like discontinuities. Finite element analysis (FEA) was used to determine linear elastic fracture mechanics stress intensities and limit states for a range of typical attachment geometries, on the assumption that these two failure conditions represent practical extremes of behaviour. The influence of differences between the yield strengths of the parent materials and the welds was explored in the theoretical study. The results of the FEA were analysed to obtain the development of appropriate design/assessment formulae, based on simple structural mechanics models. These formulae provide an approach that improves on current codes of practice, which treat the loads on welds as statically determinate and ignore crack-related failure potential. Collapse tests were carried out on two-dimensional models of the cases studied. These included specimens where the strength properties were uniform throughout and others where higher-yield-strength welds were incorporated. The results confirmed the FEA results and associated formula with respect to the limit state and provided some insight into the effects of heterogeneous strength properties in the junction.

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