scholarly journals Rational Modeling of Ultimate Pipe Strength Under Bending and External Pressure

2000 ◽  
Author(s):  
André C. Nogueira ◽  
Glenn A. Lanan
Keyword(s):  
Deep Water ◽  
Limit State ◽  
Local Buckling ◽  
External Pressure ◽  
Pressure Effects ◽  
Combined Loading ◽  
Empirical Prediction ◽  
Limit State Design ◽  
Controlled Conditions ◽  
Offshore Pipeline

The capacity of pipelines to resist collapse or local buckling under a combination of external pressure and bending moment is a major aspect of offshore pipeline design. The importance of this loading combination increases as oil and gas projects in ultra deep-water, beyond 2,000-m water depths, are becoming reality. The industry is now accepting, and codes are explicitly incorporating, limit state design concepts such as the distinction between load controlled and displacement controlled conditions. Thus, deep-water pipeline installation and limit state design procedures are increasing the need to understand fundamental principles of offshore pipeline performance. Design codes, such as API 1111 (1999) or DNV (1996, 2000), present equations that quantify pipeline capacities under combined loading in offshore pipelines. However, these equations are based on empirical data fitting, with or without reliability considerations. Palmer (1994) pointed out that “it is surprising to discover that theoretical prediction [of tubular members under combined loading] has lagged behind empirical prediction, and that many of the formula have no real theoretical backup beyond dimensional analysis.” This paper addresses the ultimate strength of pipelines under combined bending and external pressure, especially for diameter-to-thickness ratios, D/t, less than 40, which are typically used for deep water applications. The model is original and has a rational basis. It includes considerations of ovalization, anisotropy (such as those caused by the UOE pipe fabrication process), load controlled, and displaced controlled conditions. First, plastic analysis is reviewed, then pipe local buckling under pure bending is analyzed and used to develop the strength model. Load controlled and displacement controlled conditions are a natural consequence of the formulation, as well as cross section ovalization. Secondly, external pressure effects are addressed. Model predictions compare very favorably to experimental collapse test results.

Influence of Pressure in Pipeline Design: Effective Axial Force

2005 ◽  
Author(s):  
Olav Fyrileiv ◽  
Leif Collberg
Keyword(s):  
Axial Force ◽  
Local Buckling ◽  
External Pressure ◽  
Pressure Effects ◽  
Offshore Pipeline ◽  
Local Stresses ◽  
Global Buckling ◽  
The One ◽  
Pipeline Design ◽  
Force Concept

This paper discusses use of the effective axial force concept in offshore pipeline design in general and in DNV codes in particular. The concept of effective axial force or effective tension has been known and used in the pipeline and riser industry for some decades. However, recently a discussion about this was initiated and doubt on how to treat the internal pressure raised. Hopefully this paper will contribute to explain the use of this concept and remove the doubts in the industry, if it exists at all. The concept of effective axial force allows calculation of the global behaviour without considering the effects of internal and/or external pressure in detail. In particular, global buckling, so-called Euler buckling, can be calculated as in air by applying the concept of effective axial force. The effective axial force is also used in the DNV-RP-F105 “Free spanning pipelines” to adjust the natural frequencies of free spans due to the change in geometrical stiffness caused by the axial force and pressure effects. A recent paper claimed, however, that the effect was the opposite of the one given in the DNV-RP-F105 and may cause confusion about what is the appropriate way of handling the pressure effects. It is generally accepted that global buckling of pipelines is governed by the effective axial force. However, in the DNV Pipeline Standard DNV-OS-F101, also the local buckling criterion is expressed by use of the effective axial force concept which easily could be misunderstood. Local buckling is, of course, governed by the local stresses, the true stresses, in the pipe steel wall. Thus, it seems unreasonable to include the effective axial force and not the true axial force as used in the former DNV Pipeline Standard DNV’96. The reason for this is explained in detail in this paper. This paper gives an introduction to the concept of effective axial force. Further it explains how this concept is applied in modern offshore pipeline design. Finally the background for using the effective axial force in some of the DNV pipeline codes is given.

Extending the Limits for Thick Walled Pipe (D/t<20) for External Pressure and Combined Loading

2017 ◽  
Author(s):  
Henk Smienk ◽  
Erwan Karjadi ◽  
Steven Huiskes
Keyword(s):  
Limit State ◽  
Local Buckling ◽  
Bending Moment ◽  
External Pressure ◽  
Combined Loading ◽  
Load Path ◽  
Material Models ◽  
Axial Tension ◽  
Geometrical Imperfections ◽  
2D And 3D

During the operational and installation phase of submarine pipelines, the collapse and local buckling behaviour is of interest. Existing research [1] shows conservatism in the pure collapse DNV formula for thick walled pipe. The first part of the paper will focus on the collapse behaviour of empty thick walled pipe under external pressure. Using 2D and 3D FE Analysis an investigation into the collapse behaviour of pipe with a D/t < 20 is conducted. The analysis also covers an extensive sensitivity analysis with regard to geometrical imperfections and different material models. The local buckling behaviour during the combined external pressure, bending moment and effective axial force loading encountered in the sagbend is also investigated. To obtain a realistic load path for the sagbend loading, static Flexcom analyses are performed. If the load case is not sufficient to initiate collapse because of the stiffness of the catenary due to the low D/t, the pipe will be bent to the limit state while setting the effective tension to zero. The effect of each sensitivity on the collapse and local buckle behaviour of thick walled pipe in the sagbend including effective axial tension is discussed.

Parameters Study of Deep Water Subsea Pipeline Selection

2014 ◽  
Vol 69 (7) ◽  
Author(s):  
Abdul Khair Junaidi ◽  
Jaswar Koto
Keyword(s):  
Deep Water ◽  
General Trend ◽  
External Pressure ◽  
Water Project ◽  
Offshore Pipeline ◽  
Recent Developments ◽  
Pressure Limitation ◽  
Water Pipeline ◽  
Subsea Pipelines ◽  
Selection Of

Recent developments in offshore pipeline projects in Malaysia waters are showing general trend towards deeper water, such as KIKEH in 2200 meter water depth. As the exploration is getting into deeper water or crossing a deep water section, different design issues may become governing compared to shallow water. Conceptual Design for Deep Water Pipeline discusses number of issues that need to be taken onto account in the design of pipelines in deep water. Aspect related to high external pressure, limitation for installation and geo-hazards are addressed. In order to give an early insight for designer to measure the reliability for a deep water project to current technology capabilities, a simulation program required to achieve the objective. This paper discusses several factors for selection of subsea pipelines such as wall thickness, buckling arrestors design, installation configuration and free spanning.

Minimum Wall Thickness Requirements for Ultra Deep-Water Pipelines

2003 ◽  
Author(s):  
Enrico Torselletti ◽  
Luigino Vitali ◽  
Roberto Bruschi ◽  
Leif Collberg
Keyword(s):  
Wall Thickness ◽  
Deep Water ◽  
Failure Modes ◽  
Limit State ◽  
Strain Curve ◽  
External Pressure ◽  
Design Guidelines ◽  
Compressive Yield Strength ◽  
Pipe Material ◽  
Line Pipe

The offshore pipeline industry is planning new gas trunklines at water depth ever reached before (up to 3500 m). In such conditions, external hydrostatic pressure becomes the dominating loading condition for the pipeline design. In particular, pipe geometric imperfections as the cross section ovality, combined load effects as axial and bending loads superimposed to the external pressure, material properties as compressive yield strength in the circumferential direction and across the wall thickness etc., significantly interfere in the definition of the demanding, in such projects, minimum wall thickness requirements. This paper discusses the findings of a series of ultra deep-water studies carried out in the framework of Snamprogetti corporate R&D. In particular, the pipe sectional capacity, required to sustain design loads, is analysed in relation to: • The fabrication technology i.e. the effect of cold expansion/compression (UOE/UOC) of TMCP plates on the mechanical and geometrical pipe characteristics; • The line pipe material i.e. the effect of the shape of the actual stress-strain curve and the Y/T ratio on the sectional performance, under combined loads; • The load combination i.e. the effect of the axial force and bending moment on the limit capacity against collapse and ovalisation buckling failure modes, under the considerable external pressure. International design guidelines are analysed in this respect, and experimental findings are compared with the ones from the application of proposed limit state equations and from dedicated FE simulations.

FEA of a Laminate Internal Buckle Arrestor for Deep Water Pipe-in-Pipe Flowlines

2009 ◽  
Author(s):  
Haoyu Wang ◽  
Jason Sun ◽  
Paul Jukes
Keyword(s):  
Deep Water ◽  
Mechanical Design ◽  
Limit State ◽  
Local Buckling ◽  
Design Parameters ◽  
Limit States ◽  
Element Analysis ◽  
Operational Lifetime ◽  
Buckle Propagation ◽  
Buckle Arrestors

Development of deepwater oil reservoirs has been undertaken in the Gulf of Mexico (GoM) where flowlines are installed in water depths in the vicinity of 2,740m (9,000ft). Preventing the propagation of local collapse/buckle failures is one of the key engineering design limit states that is defined in the industry codes to ensure the pipeline integrity. Deep-water buckle propagation is almost unavoidable as the wall thickness selection cannot be directly driven by the buckle propagation limit state. Field data indicates that once a buckle happens, the flowline could collapse for many kilometers instantly. Buckle propagation could cause substantial economic impact if left uncontrolled. For Pipe-in-Pipe (PIP) flowline, due to lack of pressure differential, the jacket pipe is a fragile component in terms of buckle propagation. It is crucial to prevent any possible local buckling during the flowline installation and during the entire operational lifetime. One way to stop buckle propagation is to utilize buckle arrestors of various types. Successfully designed buckle arrestors can contain such disasters to a limited pipeline section. Internal buckle arrestors are a relatively new solution for PIP systems being investigated by the industry. As it is installed in the annulus of PIP, it becomes a preferred choice since it fits all types of installation methods. The objective of this paper is to present the design and finite element analysis (FEA) of a laminate type internal buckle arrestor, and to investigate the effectiveness of this innovative buckle arrestor design for deepwater flowline. Sensitivities of key design parameters are explored with the purpose of guiding detailed mechanical design.

Study on Local Buckling of District Heating Pipes Using Limit State Design

2010 ◽  
Vol 34 (12) ◽  
pp. 1829-1836
Author(s):  
Joo-Yong Kim ◽  
Sang-Youn Lee ◽  
Hyun-Il Ko ◽  
Chong-Du Cho
Keyword(s):  
Limit State ◽  
Local Buckling ◽  
District Heating ◽  
Limit State Design ◽  
Heating Pipes

Finite Element Analysis of Clamp-On Buckle Arrestor for Pipe-in-Pipe Flowlines by Reel-Lay Installation

2008 ◽  
Author(s):  
Jason Sun ◽  
Paul Jukes
Keyword(s):  
Finite Element ◽  
Deep Water ◽  
Pipe Wall ◽  
Mechanical Design ◽  
Local Buckling ◽  
External Pressure ◽  
Design Parameters ◽  
Element Analysis ◽  
Buckle Propagation ◽  
Buckle Arrestors

Development of deep water oil reservoirs are undertaken in the Gulf of Mexico (GoM) where the flowlines are installed in the water depths in excess of 3,050m (10,000ft). Deepwater external pressure becomes so significant that it makes local buckling or accidental collapse propagate along the pipeline. Such propagation will not stop until it reaches a region where the external pressure falls below the propagating pressure or where the pipe wall is strengthened. Field data indicates that once a buckle happens, the flowline could collapse many kilometers instantly. It concludes that buckle propagation could cause substantial economical impact if left uncontrolled. For pipe-in-pipe (PIP) flowline, due to lack of pressure differential, the outer pipe becomes a fragile component in terms of buckle propagation. One way to prevent the propagation of local buckling or collapse is to utilize the buckle arrestors of various types. Clamp-on buckle arrestor is so far the best choice for the flowlines to be installed by the Reel-Lay method. The objective of this paper is to present the results of a finite element (FE) study, to reveal the phenomena of collapsing/propagating of the pipe-in-pipe flowline, and to investigate the effectiveness of Clamp-on buckle arrestor for deep water flowlines. Sensitivities of key design parameters are explored with the purpose of guiding detail mechanical design of the clamp-on buckle arrestor.

Northstar Development Pipelines Limit State Design and Experimental Program

2000 ◽  
Author(s):  
André C. Nogueira ◽  
Glenn A. Lanan ◽  
Tom M. Even ◽  
Joe R. Fowler ◽  
Brett A. Hormberg
Keyword(s):  
Limit State ◽  
Experimental Program ◽  
Offshore Pipelines ◽  
Limit State Design ◽  
The North ◽  
Ice Surface ◽  
Offshore Pipeline ◽  
North Slope Of Alaska ◽  
Pipeline Welding ◽  
Prudhoe Bay

BP Exploration (Alaska) Inc. (BPXA) and its Northstar Project Alliance contractors started field construction of the Northstar development in January 2000 (Lanan et al. 2000). In April 2000, the offshore section of the Northstar pipeline reached Seal Island, located in 11 m water depth Northwest of Prudhoe Bay. Seal Island is in the Beaufort Sea, 9.7 km offshore from the shore crossing at Point Storkersen, on the North Slope of Alaska. Design, testing and permitting activities required multiple years leading up to this first of it kind pipeline construction project. Figure 1 shows the offshore pipeline welding spread working on the floating sea ice surface, similar to the conventional procedures used on the overland portion of the Northstar pipeline. This paper presents the limit state design of the offshore pipelines and the associated full-scale experimental program, which demonstrated that the pipelines can safely withstand operational bending strains up to 1.8%.

Limit Load Capacity of Thick-Walled Pipe Loaded by Internal Pressure and Bending

2021 ◽  
Author(s):  
Ruud Selker ◽  
Joost Brugmans ◽  
Ping Liu ◽  
Carlos Sicilia
Keyword(s):  
Finite Element ◽  
Internal Pressure ◽  
Wall Thickness ◽  
Load Capacity ◽  
Limit State ◽  
Local Buckling ◽  
Limit Load ◽  
Combined Loading ◽  
Fe Model ◽  
State Equations

Abstract Internally pressurised pipe behaves differently than externally pressurised pipe. DNVGL-ST-F101 [4], a prevailing standard for the design of submarine pipelines, provides limit-state equations for combined loading that are valid only if the diameter-to-wall-thickness ratio (D/t) is between 15 and 45. A recent study has shown that the results are increasingly conservative for lower values of this ratio if the nett pressure is acting on the pipe’s outside [8], especially if it is below 20. In this paper, the applicability of the limit-state equations for thick-walled pipe with D/t less than 15 and loaded by a nett internal pressure has been investigated. The first step was a fundamental review of the formulations. Next, the predicted capacities were compared with those estimated using a finite-element (FE) model. The results greatly coincided, which indicates that the conservatism underlying the formulations does not depend on D/t. Hence they can be used for design against local buckling under internal overpressure, too, when the ratio is below 15.

Flexible Riser Resistance Against Combined Axial Compression, Bending, and Torsion in Ultra-Deep Water Depths

2005 ◽  
Author(s):  
Marcelo Brack ◽  
Le´a M. B. Troina ◽  
Jose´ Renato M. de Sousa
Keyword(s):  
Axial Compression ◽  
Deep Water ◽  
Failure Modes ◽  
External Pressure ◽  
Combined Loading ◽  
Test Procedures ◽  
Pipe Length ◽  
Potential Failure ◽  
Technical Specifications ◽  
Water Depths

The experience in the Brazilian offshore production systems is to adopt the traditional riser solution composed of unbonded flexible pipes at a free-hanging catenary configuration. In deep waters, the tendency has been to use different pipe length sections (normally two), each of them designed to resist typical loadings. At the bottom, pipe structure is dimensioned against external pressure, axial compression, bending and torsion, for example. The theoretical prediction of riser responses under the crescent combined loading conditions is a key issue at the TDP region. The potential failure modes are buckling of the armour tendons and also rupture of the high resistance tapes. Much effort has been done in order to have available, from the market, larger envelopes of certified methodologies and qualified products, applicable to the Brazilian ultra-deep scenarios. Since 2002, an extensive R&D Program has been conducted (i) to improve current design evaluation tools & criteria and (ii) to establish representative test procedures and scope, for prototype qualification against the potential failure modes associated with combined axial compression, bending and torsion, at the TDP regions of bottom riser sections in ultra-deep water depths. This paper describes the main steps of the R&D Program, as below: I. Improvement of computational tools to better represent the behavior of the tendons, II. Consolidation of a new strategy for structural analysis, under more realistic conditions, III. Issue of a more adequate set of pipe technical specifications, and IV. Review of both theoretical and experimental results obtained from Feasibility Technical Studies and offshore field tests, respectively. Some examples and results are showed to illustrate, step by step, the whole process covered by the cited Program. Finally, the authors document their main conclusions for further discussion.

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