Buckle Propagation and Its Arrest: Buckle Arrestor Design Versus Numerical Analyses and Experiments

2003 ◽  
Author(s):  
Enrico Torselletti ◽  
Roberto Bruschi ◽  
Furio Marchesani ◽  
Luigino Vitali
Keyword(s):  
Structural Reliability ◽  
External Pressure ◽  
Numerical Analyses ◽  
Potential Hazard ◽  
Line Pipe ◽  
Deep Waters ◽  
Offshore Pipeline ◽  
Reliability Methods ◽  
Buckle Propagation ◽  
Buckle Arrestors

Buckle propagation under external pressure is a potential hazard during offshore pipeline laying in deep waters. It is normal design practice to install thicker pipe sections which, in case of buckle initiation and consequent propagation, can stop it so avoiding the lost of long pipe sections as well as threats to the installation equipment and dedicated personnel. There is still a series of questions the designer needs to answer when a new trunkline for very deep water applications is conceived: • What are the implications of the actual production technology (U-ing, O-ing and Expansion or Compression e.g. UO, UOE and UOC) on the propagation and arrest capacity of the line pipe, • How formulations for buckle arrestors design can be linked to a safety objective as required in modern submarine pipeline applications. The answers influence any decision on thickness, length, material and spacing of buckle arrestors. This paper gives an overview of buckle propagation and arrest phenomena and proposes a new design equation, applicable for both short and long buckle arrestors, based on available literature information and independent numerical analyses. Partial safety factors are recommended, based on a calibration process performed using structural reliability methods. Calibration aimed at fulfilling the safety objectives defined in DNV Offshore Standards OS-F101 and OS-F201.

Efficiency of Carbon Fibre Buckle Arrestors for Subsea Pipelines

2019 ◽  
Author(s):  
Hassan Karampour ◽  
Mahmoud Alrsai ◽  
Wayne Hall
Keyword(s):  
Pressure Gauge ◽  
External Pressure ◽  
Hyperbaric Chamber ◽  
Reinforced Polymer ◽  
Dog Bone ◽  
Buckle Propagation ◽  
Pipeline Wall ◽  
Subsea Pipelines ◽  
Buckle Arrestors ◽  
Hoop Direction

Abstract This paper experimentally investigates the feasibility and efficiency of using Carbon Fiber Reinforced Polymer (CFRP) buckle arrestors in controlling the buckle propagation failure of subsea pipelines. Hyperbaric chamber tests are conducted on 1.6m Steel pipe with D/t = 28 and using CFRP buckle arrestors with different thickness, fiber orientation and spacing. Using an external pressure gauge and a high-pressure camera inserted inside the hyperbaric chamber, the pressure magnitude, rate and shape of collapse and its propagation in the vicinity of the arrestors are measured. The dynamics of buckle propagation and efficiency of different arrestor configurations are reported. It is observed that in the vicinity of the CFRP arrestors wrapped in the hoop direction, the well-known dog-bone buckle shape changes into a U-shape and the pressure level upsurges significantly. The optimum results were obtained with CFRP as thick as the pipeline wall-thickness and wrapped in the hoop direction of the pipeline. The results show that at similar arrestor efficiency, the CFRP arrestors can be much thinner than the existing steel slip-on arrestors. Also, the spacing between the CFRP arrestor can be larger than that of the steel slip-on arrestor.

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.

Comparison of Numerical Results and Design Criteria for Buckle Propagation and Buckle Arrestor Design

2006 ◽  
Author(s):  
Thomas Plonski ◽  
Gundula Stadie-Frohbo¨s ◽  
Gordon Jokisch
Keyword(s):  
Wall Thickness ◽  
External Pressure ◽  
Design Criterion ◽  
Numerical Results ◽  
Design Criteria ◽  
Technical Solution ◽  
Offshore Pipelines ◽  
External Impact ◽  
Buckle Propagation ◽  
Buckle Arrestors

Buckle propagation is a relevant design criterion for deep-water offshore pipelines. Imposed by external impact or local bending, e.g. during laying, a local buckle can be initiated, thereby decreasing the collapse strength of the pipeline. As a result of the high ambient external pressure, the buckle can start to propagate. Several design criteria for buckle propagation exist. This paper compares different design criteria with numerical results to obtain an impression of the levels of conservatism applied in the various codes. In most design cases, it is not suitable to avoid buckle propagation by using an increased wall thickness over the entire pipeline. Therefore, buckle arrestors are installed to stop the propagation. The common technical solution is to install sections of thicker pipeline, which requires that the buckle arrestor wall thickness and the length of the buckle arrestor have to be determined during design. A distinction is drawn between short and long buckle arrestors. Both cases are considered here. The design of the buckle arrestor can be carried out by using well-known criteria, such as the criteria developed by Kyriakides, Langner or Torselletti et al. These criteria are compared with experimental data. Numerical calculations are carried out and the results are compared with the design criteria.

Safety Factors Calibration for Wall Thickness Design of Ultra Deepwater Pipelines

2013 ◽  
Author(s):  
Eduardo Oazen ◽  
Bruno R. Antunes ◽  
Carlos O. Cardoso ◽  
Rafael F. Solano
Keyword(s):  
Safety Factor ◽  
Wall Thickness ◽  
Structural Reliability ◽  
Limit State ◽  
Large Diameter ◽  
Design Codes ◽  
Safety Factors ◽  
Offshore Pipeline ◽  
Reliability Methods ◽  
Pipeline Design

Wall thickness often presents a considerable influence in offshore pipeline capital expenditure (CAPEX). This influence is enhanced in design of ultra deepwater trunk lines of large diameter, where any wall thickness increase provides a huge impact on project costs. In ultra deepwater scenarios, thicker pipelines may eventually implicate not only in higher costs, but may also compromise the project feasibility due to installation load constraints related to laying vessels availability. One potential way to reduce the pipeline wall thickness is to calibrate fitness-for-purpose safety factors through application of structural reliability methods, instead of utilizing the standardized safety factors presented in international codes. Since mid-nineties, several offshore pipeline design codes have been allowing the calibration of safety factors by structural reliability analysis. The purpose of such an allowance is that structural reliability methods would eliminate some eventual conservatism presented in the safety factors proposed by codes. Although this enables the achievement of optimized safety factors, more than fifteen years have passed and only few pipeline projects have taken advantage of the benefits of safety factor calibration. This paper evaluates which potential benefits are available through safety factor calibration, particularly for wall thickness reduction purposes in ultra deepwater pipeline design. Calibrated safety factors are presented for some scenarios related to ultra deepwater export pipelines, considering “system collapse criteria” limit state. The calibrated safety factors are compared with the standardized safety factors presented by international pipeline design codes. The potential for safety factor reduction by the utilization of linepipes with more stringent manufacturing tolerances and the consideration of the thermal ageing imposed by coating application are also discussed.

scholarly journals A Practical Nonprobabilistic Reliability Assessment Method on Key Strata Shear Failure in Longwall Mining

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Hebing Luan ◽  
Jiachen Wang ◽  
Guowei Ma ◽  
Ke Zhang
Keyword(s):  
Structural Reliability ◽  
Shear Failure ◽  
Longwall Mining ◽  
Reliability Assessment ◽  
Friction Angle ◽  
Assessment Method ◽  
Mechanical Tests ◽  
Potential Hazard ◽  
Support Design ◽  
Key Strata

Roof cutting has long been a potential hazard factor in longwall panels in some diggings in China. Meanwhile, the key strata structural reliability, which provides an assessment on the stability of overlying roof strata, may be a significant reference for support design in underground coal mines. This paper aims to investigate a practical nonprobabilistic reliability assessment method on key strata. The mechanical tests and the hollow inclusion triaxial strain tests were conducted to measure relevant mechanical parameters and in situ stress. Furthermore, against the typical failure features in Datong Diggings, China, a shear failure mechanical model of key strata is proposed. Then, an allowable-safety-factor based nonprobabilistic stability probability assessment method is given. The sensitivity of geometrical dimensions and uncertainty levels of friction angle and cohesion are further studied. It is found that thickness and span of key strata have more dominative effect on key strata’s stability compared with the other factor and the increase of uncertainty levels results in decrease of stability probability.

Effect of Full- and Small-Scale Reeling Simulation on Mechanical Properties of Weldable 13Cr Seamless Line Pipe

2013 ◽  
Author(s):  
Hidenori Shitamoto ◽  
Nobuyuki Hisamune
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
Oil And Gas ◽  
Small Scale ◽  
Line Pipe ◽  
Offshore Pipeline ◽  
Oil And Gas Pipelines ◽  
Before And After ◽  
Offshore Oil And Gas ◽  
Offshore Oil

There are several methods currently being used to install offshore oil and gas pipelines. The reel-lay process is fast and one of the most effective offshore pipeline installation methods for seamless, ERW, and UOE line pipes with outside diameters of 18 inches or less. In the case of the reel-laying method, line pipes are subjected to plastic deformation multiplication during reel-laying. It is thus important to understand the change of the mechanical properties of line pipes before and after reel-laying. Therefore, full-scale reeling (FSR) simulations and small-scale reeling (SSR) simulations are applied as evaluation tests for reel-laying. In this study, FSR simulations were performed to investigate the effect of cyclic deformation on the mechanical properties of weldable 13Cr seamless line pipes. Furthermore, SSR simulations were performed to compare the results obtained by FSR simulations.

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.

Structural Reliability Methods Applied in Analysis of Steel Elements Subjected to Fire

2021 ◽  
Vol 147 (12) ◽  
pp. 04021108
Author(s):  
Alverlando Silva Ricardo ◽  
Wellison José de Santana Gomes
Keyword(s):  
Structural Reliability ◽  
Reliability Methods

Numerical Simulation of UOE Pipe Process and its Effect on Pipe Mechanical Behavior in Deep-Water Applications

2015 ◽  
Author(s):  
Giannoula Chatzopoulou ◽  
Spyros A. Karamanos ◽  
George E. Varelis
Keyword(s):  
Deep Water ◽  
Manufacturing Process ◽  
Large Diameter ◽  
Structural Response ◽  
Structural Instability ◽  
External Pressure ◽  
Line Pipe ◽  
Simulation Tools ◽  
Large Diameter Pipes ◽  
Pipe Manufacturing

Large-diameter thick-walled steel pipes during their installation in deep-water are subjected to a combination of loading in terms of external pressure, bending and axial tension, which may trigger structural instability due to excessive pipe ovalization with catastrophic effects. In the present study, the UOE pipe manufacturing process, commonly adopted for producing large-diameter pipes of significant thickness, is considered. The study examines the effect of UOE line pipe manufacturing process on the structural response and resistance of offshore pipes during the installation process using nonlinear finite element simulation tools.

Initiation of Propagating Buckles From Local Pipeline Damages

1984 ◽  
Vol 106 (1) ◽  
pp. 79-87 ◽  
Author(s):  
S. Kyriakides ◽  
C. D. Babcock ◽  
D. Elyada
Keyword(s):  
Parametric Study ◽  
External Pressure ◽  
Maximum Diameter ◽  
Minimum Diameter ◽  
Geometric Imperfection ◽  
Geometric Characteristics ◽  
Offshore Pipeline ◽  
Initiation Pressure ◽  
The Subject

The paper deals with the subject of initiation of a propagating buckle in an offshore pipeline. If the external pressure is high enough, then a propagating buckle can be initiated by locally denting the pipe. Such a buckle will propagate at any pressure above the propagation pressure of the pipe. The pressure at which a local geometric imperfection transforms itself into a propagating buckle is known as the initiation pressure. This pressure depends on the geometric characteristics of the damage. The paper restricts itself to a parametric study of damages produced by point, knife and plate indentors. It is found that the geometry of these types of damages can be well represented by the ratio of minimum diameter: maximum diameter of the most damaged section.

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