On the collapse failure of dented pipes under bending moment and external pressure

2016 ◽  
Author(s):  
Sun-ting Yan ◽  
Xiao-li Shen ◽  
Hao Ye ◽  
Zhan-feng Chen ◽  
Xuan He ◽  
...  
Keyword(s):  
Bending Moment ◽  
External Pressure ◽  
Collapse Failure

Submarine Pipeline Installation JIP: Strength and Deformation Capacity of Pipes Passing Over the S-Lay Vessel Stinger

2006 ◽  
Author(s):  
Enrico Torselletti ◽  
Luigino Vitali ◽  
Erik Levold ◽  
Kim J. Mo̸rk
Keyword(s):  
Water Depth ◽  
Failure Modes ◽  
Bending Moment ◽  
External Pressure ◽  
Submarine Pipeline ◽  
Design Guideline ◽  
Moment Capacity ◽  
Sea Bottom ◽  
Major Vessel ◽  
Gas Fields

The development of deep water gas fields using trunklines to carry the gas to the markets is sometime limited by the feasibility/economics of the construction phase. In particular there is a market for using S-lay vessels in water depth larger than 1000m. The S-lay feasibility depends on the applicable tension at the tensioner which is a function of water depth, stinger length and stinger curvature (for given stinger length by its curvature). This means that, without major vessel up-grading and to avoid too long stingers that are prone to damages caused by environmental loads, the application of larger stinger curvatures than presently allowed by current regulations/state of the art is needed. The work presented in this paper is a result of the project “Development of a Design Guideline for Submarine Pipeline Installation” sponsored by STATOIL and HYDRO. The technical activities are performed in co-operation by DNV, STATOIL and SNAMPROGETTI. The scope of the project is to produce a LRFD (Load Resistant Factor Design) design guideline to be used in the definition and application of design criteria for the laying phase e.g. to S and J-lay methods/equipment. The guideline covers D/t from 15 to 45 and applied strains over the overbend in excess of 0.5%. This paper addresses the failure modes relevant for combined high curvatures/strains, axial, external pressure and local forces due to roller over the stinger of an S-lay vessel and to sea bottom contacts, particularly: • Residual pipe ovality after laying, • Maximum strain and bending moment capacity. Analytical equations are proposed in accordance with DNV OS F101 philosophy and design format.

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

2013 ◽  
Author(s):  
Erik Levold ◽  
Andrea Restelli ◽  
Lorenzo Marchionni ◽  
Caterina Molinari ◽  
Luigino Vitali
Keyword(s):  
Failure Modes ◽  
State Of The Art ◽  
Local Buckling ◽  
Bending Moment ◽  
External Pressure ◽  
Fe Model ◽  
Deformation Capacity ◽  
Offshore Pipelines ◽  
Strength And Deformation ◽  
Bending Loading

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 E&P and Statoil has been launched with the objective to quantify and assess the strength and deformation capacity of corroded pipes in presence of internal overpressure and axial/bending loading. In this paper: • The State-of-the-Art on strength and deformation capacity of corroded pipes is presented; • 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.

scholarly journals Study on the characteristics of pipe buckling strength under pure bending and external stress using nonlinear finite element analysis

2021 ◽  
Vol 12 (2) ◽  
pp. 110-116
Author(s):  
Hartono Yudo ◽  
Wilma Amiruddin ◽  
Ari Wibawa Budi Santosa ◽  
Ocid Mursid ◽  
Tri Admono
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Bending Moment ◽  
Nonlinear Finite Element Analysis ◽  
External Pressure ◽  
Diameter Ratio ◽  
Nonlinear Finite Element ◽  
Pure Bending ◽  
Element Analysis ◽  
Buckling Strength

Buckling and collapse are important failure modes for laying and operating conditions in a subsea position. The pipe will be subjected to various kinds of loads, i.e., bending moment, external pressure, and tension. Nonlinear finite element analysis was used to analyze the buckling strength of the pipe under pure bending and external pressure. The buckling of elastic and elasto-plastic materials was also studied in this work. The buckling strength due to external pressure had decreased and become constant on the long pipe when the length-to-diameter ratio (L/D) was increased. The non-dimensional parameter (β), which is proportionate to (D/t) (σy/E), is used to study the yielding influence on the buckling strength of pipe under combined bending and external pressure loading. The interaction curves of the buckling strength of pipe were obtained, with various the diameter-to-thickness ratio (D/t) under combination loads of external pressure and bending moment. For straight pipes L/D = 2.5 to 40, D = 1000 to 4000 mm, and D/t = 50 to 200 were set. The curved pipes D/t = 200, L/D =2.5 to 30 have been investigated by changing the radius of curvature-to-diameter ratio (R/D) from 50 to ∞, for each one. With decreasing R/D, the buckling strength under external pressure decreases slightly. This is in contrast to the bending of a curved pipe. When the value of R/D was decreased, the flexibility of the pipe was increased. However, the buckling strength of the pipe during bending was decreased due to the oval deformation at the cross-section.

scholarly journals Buckling analysis of thin-walled metal liner of cylindrical composite overwrapped pressure vessels with depressions after autofrettage processing

2021 ◽  
Vol 28 (1) ◽  
pp. 540-554
Author(s):  
Guo Zhang ◽  
Haiyang Zhu ◽  
Qi Wang ◽  
Xiaowen Zhang ◽  
Mingfa Ren ◽  
...  
Keyword(s):  
Pressure Vessel ◽  
Local Buckling ◽  
Bending Moment ◽  
High Strength ◽  
External Pressure ◽  
Pressure Vessels ◽  
Buckling Analysis ◽  
Straight Section ◽  
Metal Liner ◽  
Autofrettage Pressure

Abstract The cylindrical filament wound composite overwrapped pressure vessels (COPV) with metal liner has been widely used in spaceflight due to their high strength and low weight. After the autofrettage process, the plastic deformation of the metal liner is constrained by composite winding layers, which introduce depressions to the metal liner that causes local buckling. To predict the local buckling of the inner liner with depressions of the pressure vessel after the autofrettage process, a local buckling analysis method for the metal liner of COPV was developed in this article. The finite element method is used to calculate the overall stress distribution in the pressure vessel before and after the autofrettage process, and the influence of local depressions on the buckling is evaluated. The axial buckling of the pressure vessel under external pressure is analyzed. The control equation of the metal liner with depressions is developed, considering the changes in the pressure and the bending moment of the liner depressions and its vicinity during the loading and unloading process. Taking the cylindrical COPV (38 L) with aluminum alloy liner as an example, the effects of liner thickness, liner radius, the thickness-to-diameter ratio, autofrettage pressure, and the length of straight section on the autofrettage process are discussed. The results show that the thickness of the inner liner has the most significant influence on the buckling of the liner, followed by the length of the straight section and the radius of the inner liner, while the autofrettage pressure has the least influence.

Calculation Methods of the Local Structure Behavior of Unbonded Flexible Pipes

2013 ◽  
Vol 658 ◽  
pp. 481-486
Author(s):  
Zhi Bo Li ◽  
Hui Xu ◽  
Gui Zhen Zhang
Keyword(s):  
Local Structure ◽  
Axial Load ◽  
Bending Moment ◽  
External Pressure ◽  
Nonlinear Relationship ◽  
Calculation Methods ◽  
Flexible Pipes ◽  
Bending Load ◽  
Unbonded Flexible Pipes ◽  
Moment Load

In this paper, the nonlinear relationship between the bending moment and curvature of non-bonded flexible pipes was studied. It was found that the relation was a function of internal and external pressure, axial force, and bending moment load. The model used in this paper took into consideration of the flexural, tensile and torsional strength of layers as well as the frictions between them. Symmetrical axial load was first applied, and then the bending load. Due to friction, the response of the unbonded flexible pipes is hysteretic to the loads. In conclusion, the response of unbonded flexible pipes are both related to its own structural properties and external loads.Coupling factors of different conditions should also be considered.

Flexible Pipe Curved Collapse Resistance Calculation

2009 ◽  
Author(s):  
Laurent Paumier ◽  
Daniel Averbuch ◽  
Antoine Felix-Henry
Keyword(s):  
Failure Modes ◽  
Analytical Calculation ◽  
External Pressure ◽  
Calculation Model ◽  
Third Party ◽  
Flexible Pipe ◽  
The Past ◽  
Curved Pipes ◽  
Pressure Resistance ◽  
Collapse Failure

In the design of flexible pipelines for offshore field developments, the determination of the pipe resistance while subjected to external pressure and bending is very important in deepwater and is now required by the ISO and API standards. One of the critical failure modes being associated with this type of loads is the hydrostatic collapse. The collapse value of flexible pipe is calculated with a model validated with over 200 tests performed on all possible pipe constructions. This model has an analytical basis, and has been established in the past, leading to a fast and straightforward use. In order to address the bent collapse failure mode, Technip and IFP have therefore developed and improved over the past few years an analytical calculation model, based on the collapse model for straight pipes. The purpose of this paper is to present this design methodology and its validation. The modelling principles of the collapse calculation of straight flexible pipes are firstly presented, along with the main hypotheses. The adaptation to the case of curved pipes is detailed in the sequel of the paper. Many types of flexible pipe samples have been tested up to collapse both in straight and curved configurations. The results of these tests have been used to validate this model. In the paper, several tests results will be presented and compared with the calculations. This model is effective, of straightforward use, and has been certified by a third party. It allows Technip to optimize the flexible pipe design in particular for ultra-deep water applications, where external pressure resistance is very important.

Developments in Testing and Manufacture of Thick-Walled Pipe

2017 ◽  
Author(s):  
Alastair Walker ◽  
Jayden Chee ◽  
Peter Roberts
Keyword(s):  
Safety Factor ◽  
Deep Water ◽  
Maximum Level ◽  
External Pressure ◽  
Full Scale ◽  
Test Facility ◽  
Collapse Pressure ◽  
Pipe Joints ◽  
Collapse Failure ◽  
Pipe Joint

Over the past 20 years there has been a considerable development of the capability to design and manufacture thick walled pipe to manufacture pipelines to operate in ultra-deep water. Design guidance is available in DNV OS F101 [1] in which the safety from pressure collapse failure during pipeline installation is determined by the use of a safety factor. The safety factor has been calibrated using the Load and Resistance Factor Design (LRFD) method in comparison with collapse pressure test results available at the time of preparation of DNV guidance. Because of the huge financial implications of loss of a very long pipeline during installation in ultra-deep water it has been the practice further to base the design of such a pipeline on specific pipe joint collapse tests in conjunction with the DNV information. Pressure testing full-scale pipe joints is an expensive undertaking that requires a suitable pressure chamber. Only a few chambers capable of applying pressures corresponding to very deep water are available in the world and transport of the pipes from the pipe mill to a suitable test facility may be very inconvenient and certainly expensive. This paper describes an alternative approach which could provide data that would enable the preparation of a safe approach specific to the pipeline diameter and design water depth. The approach could enable optimisation of the pipe design, particularly the pipe wall thickness. The proposed method is based on replacing costly full scale pipe tests by corresponding tests on ring specimens cut and machined from manufactured pipe joints. The proposal to use ring testing as the basis for design has been included successfully in the design of pipe for a recent ultra-deep water project [2]. The paper describes equipment used to subject the rings to external pressure and reports on tests carried out to validate the correspondence between the ring collapse pressure and that for the pipe joint from which the ring was obtained. Based on results from such tests it is concluded in this paper that ring pressure collapse testing is indeed a valid method to use as the basis for the design pipes in the next stage of ultra-deep water, i.e. increasing the capability to install pipeline in water depths down to 3500m from the current maximum level of 2500m.

Collapse of reinforced thermoplastic pipe (RTP) under combined external pressure and bending moment

2015 ◽  
Vol 94 ◽  
pp. 10-18 ◽  
Author(s):  
Yong Bai ◽  
Jiandong Tang ◽  
Weiping Xu ◽  
Yu Cao ◽  
Ruoshi Wang
Keyword(s):  
Bending Moment ◽  
External Pressure

Reliability Analysis of a Steel Catenary Riser With Environmental, Geometry, and Operational Uncertainties

2014 ◽  
Author(s):  
C. Y. Ma ◽  
U. Alibrandi ◽  
C. G. Koh
Keyword(s):  
Failure Probability ◽  
Bending Moment ◽  
External Pressure ◽  
Engineering Practice ◽  
Floating Structure ◽  
Steel Catenary Riser ◽  
Waves And Currents ◽  
Uncertainty Parameters ◽  
Environmental Geometry ◽  
Scr Model

Steel Catenary Riser (SCR) offers an attractive solution to deepwater floating structure due to its economical effectiveness, large diameters, high resistance to internal and external pressure, simple and robust installation methods. SCR forms a prolongation of a subsea flowline attached to a fixed platform or a floating unit in a catenary shape. Due to the relatively large motion under waves and currents, SCR lines are sensitive to dynamic effects and vulnerable to damage in deep water. They are commonly subjected to high top tension and large bending moment due to platform or FPSO movements which may lead to fatigue damage. There are many uncertainties that can affect the safety and cost-effectiveness of the SCR. Offshore design codes typically adopt empirical safety factors to account for these uncertainties but this approach does not permit the prediction of failure probability of the riser system. To address the above issue, this paper presents the coupling of the stochastic analysis concept to the deterministic computational model for the dynamic analysis of SCR. The finite element solution is developed for hydrodynamic and structural analysis accounting for nonlinear and dynamic coupling effects. Methods for reduction of dimensionality of uncertainties are investigated to help to make the analysis computationally feasible. Uncertainty and numerical realization of specific uncertainty parameters are modeled through riser dynamics software and uncertainty analysis software. Distributions of effective tension, bending moment, and API RP 2RD stress are illustrated for a specified SCR model. The correlation effects between structural responses and random variables are investigated. In addition, the failure probability of SCR API RP 2RD stress is investigated through Monte Carlo simulations. This will help to evaluate the behavior and reliability of SCR realistically, incorporating the environmental, geometry and operational uncertainties in engineering practice.

Bending Capacity of Pipe Bends in Deepwater Conditions

2010 ◽  
Author(s):  
Shulong Liu ◽  
Alastair Walker ◽  
Philip Cooper
Keyword(s):  
Internal Pressure ◽  
Induction Heating ◽  
Wall Thickness ◽  
Failure Modes ◽  
Limit State ◽  
Bending Moment ◽  
External Pressure ◽  
Fe Method ◽  
Moment Capacity ◽  
Operation Conditions

Offshore pipeline systems commonly incorporate induction-heating formed bends along flowlines and in pipeline end termination assemblies and spools. In deepwater locations, the pipeline and bends are subjected to various combinations of external pressure, internal pressure, bending moment and temperature changes, during installation, and operation. Although there is a history of research into the limiting loads and failure modes of such bends and pipelines systems there is, as yet, no comprehensive guidance to enable the calculation of the maximum capacity under combined bending and external pressure loading. Conservative guidance is presented in DNV OS-F101 (2007) [1] that proposes increasing the pipe wall thickness to reduce the effect of external pressure collapse effects thus enabling bending formulations relevant to straight pipe to be used. This proposed approach leads to unfeasibly large wall thickness requirements in very deepwater applications. There is therefore a requirement for a method to design deepwater bends for installation and operation conditions with levels of safety comparable with those used in the design of straight sections of pipelines that does not depend on the requirement to increase the wall thickness to the extent proposed in the current DNV guidance. In this study, a nonlinear FE method using ABAQUS is proposed to evaluate the ultimate capacities of induction-heating formed bends. The method takes into account the combined effects of non-linear material properties, initial ovality, wall thinning/thickening, external or internal pressure, internal CRA cladding and temperature change on the ultimate moment capacity of the bend. The numerical model is validated by comparison with available published results. The method developed here is based on the limit state design formulations in the current DNV OS-F101 guidance.

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