scholarly journals Predicting Pipeline Collapse Resistance

2000 ◽  
Author(s):  
Duane DeGeer ◽  
J. J. Roger Cheng
Keyword(s):  
Prediction Method ◽  
External Pressure ◽  
Test Results ◽  
Spreadsheet Program ◽  
Axial Tension ◽  
Collapse Resistance ◽  
Inelastic Material ◽  
Post Buckling ◽  
Manufacturing History ◽  
Semi Empirical

Much research has been performed over the past twenty-five years to refine our basic understanding of tubular stability, which includes bifurcation, imperfect systems, factors influencing tubular stability and post-buckling behaviour. Tubular instability resulting from load combinations is not a trivial topic, particularly when inelastic material behaviour occurs. Many influencing factors must be considered when attempting to understand (and predict) the onset of instability. Many existing collapse predictive methods are either simplistic or involve advanced plasticity or finite element methods. Simplistic methods are typically semi-empirical, and contain a degree of uncertainty resulting in conservative collapse predictions. Nonetheless, they are generally considered satisfactory for design purposes. Advanced methods normally involve high-end calculations using specialized software programs that might not be available for general use. Therefore, a relatively easy-to-use method that accurately predicts the actual collapse resistance is, in many cases, the most desirable option. This paper presents a collapse predictive methodology, developed from a variety of research projects performed over the last fifteen years. The prediction method, which can easily be entered into a spreadsheet program, is applicable to most forms of tubular members, including pipelines. Applicable load combinations include external pressure, axial tension and bending. An overview of the parameters influencing collapse resistance is also provided, including manufacturing history, material modelling, and tubular geometry and imperfections. Also presented is a summary of accuracy of the method to predict some test results. The test database largely contains results of collapse tests on tubular members subject to only external pressure, and axial tension with external pressure. The adaptation of the method to include external pressure with bending is summarized, and the accuracy of the prediction method is demonstrated by predicting the results of the Oman-India and Blue Stream pipeline collapse test programs, and comparing these predictions with those of other well known methodologies.

The Effect of Length: Diameter Ratio on Collapse of Casing

1984 ◽  
Vol 106 (2) ◽  
pp. 160-165 ◽  
Author(s):  
N. C. Huang ◽  
P. D. Pattillo
Keyword(s):  
Axial Load ◽  
External Pressure ◽  
Field Application ◽  
Diameter Ratio ◽  
Finite Cylinder ◽  
Oil Well ◽  
Steel Mill ◽  
Cross Sectional ◽  
Axial Tension ◽  
Collapse Resistance

This paper presents an analysis of the cross-sectional collapse of a cylinder of finite length loaded simultaneously by an axial tension (which may be zero) and external pressure. The calculation is based on Sanders’ nonlinear shell equations with plasticity introduced via the concept of effective stress from a uniaxial tension test. The finite cylinder is an appropriate model of oil well casing as it undergoes quality control testing in the steel mill where the edges of the cylinder are usually fixed in the case of nonzero axial load and free in the case of zero axial load. However, in field application, the length: diameter ratio of casing is such that the cylinder may be considered infinite. Guidelines contained herein permit prediction of the collapse resistance of field casing from the results of mill tests performed on short samples.

On the Plastic Buckling Paradox for Cylindrical Shells

1996 ◽  
Vol 210 (5) ◽  
pp. 477-488 ◽  
Author(s):  
J Blachut ◽  
G D Galletly ◽  
S James
Keyword(s):  
Biaxial Loading ◽  
Flow Theory ◽  
External Pressure ◽  
Test Results ◽  
Plastic Buckling ◽  
Shell Buckling ◽  
Axial Tension ◽  
Plate And Shell ◽  
Shell Models ◽  
Flow Theories

Previous investigations have raised some doubts about the accuracy of flow theory predictions for a few plate and shell plastic buckling problems. The present series of buckling experiments on machined, mild steel, cylindrical shell models under non-proportional biaxial loading (axial tension plus external pressure) was designed to provide additional data for the evaluation of the J2 plasticity theories. Numerical calculations were carried out with the BOSOR 5 shell buckling program, using the J2 deformation and flow theories, and these were compared with the test results. Neither theory can be said to predict plastic buckling accurately. However, deformation theory predicted the bifurcation buckling loads reasonably well, whereas flow theory was often incorrect.

Anisotropic Loading Functions for Combined Stresses in the Plastic Range

1955 ◽  
Vol 22 (1) ◽  
pp. 77-85
Author(s):  
L. W. Hu ◽  
Joseph Marin
Keyword(s):  
Plastic Flow ◽  
Biaxial Tension ◽  
Strain History ◽  
Test Results ◽  
Axial Tension ◽  
State Of Stress ◽  
Loading Function ◽  
Combined Stresses ◽  
Shift Of Origin ◽  
Tubular Specimens

Abstract A loading function is a relation between combined stresses for which the beginning of plastic flow takes place. The loading function for a given material is different depending upon the initial plastic strains produced. That is, the initial stress or strain history influences the subsequent loading function. This paper gives the results of an experimental investigation to determine the validity of certain loading functions proposed for anisotropic materials. The study reported was conducted for an aluminum alloy 24S-T and the state of stress covered was biaxial tension. These stresses were produced in the usual way by subjecting thin-walled tubular specimens to axial tension and internal pressure. The test results showed that none of the existing loading functions is adequate for interpreting the plastic stress-strain relations obtained. Tests also were made to determine the change in the loading function with increase in plastic flow. It was found that the loading function did not remain symmetrical with respect to the original function, nor was the new loading function the same as the original except for a shift of origin. However, the test results support in a qualitative way the concept of the so-called “yield corner.”

On Some Factors Affecting Casing Collapse Resistance under External Pressure

2020 ◽  
Author(s):  
Bisen Lin ◽  
David Coe ◽  
Richard Harris ◽  
Timothy Thomas
Keyword(s):  
External Pressure ◽  
Factors Affecting ◽  
Collapse Resistance ◽  
Casing Collapse

Application of a General Technique for Prediction of Riser Vortex-Induced Response in Waves and Current

1989 ◽  
Vol 111 (2) ◽  
pp. 82-91 ◽  
Author(s):  
G. J. Lyons ◽  
M. H. Patel
Keyword(s):  
Time Domain ◽  
Calculation Method ◽  
Prediction Method ◽  
Induced Response ◽  
Flow Properties ◽  
General Technique ◽  
Prediction Technique ◽  
Combined Action ◽  
Semi Empirical ◽  
Surface Vessel

This paper describes applications of an extension to a recently developed calculation method for vortex-induced response of risers and tethers. The vortex-induced vibration response for the excited modes is generated using a semi-empirical formulation which is applied within a time domain calculation. This makes it possible to take account of the variation of flow properties along the riser length, as well as in time. The calculation method has been verified by comparison with model test data for vortex-induced response to surface vessel motions in still water. This paper presents applications of the technique for vortex shedding due to the combined action of current, surface vessel motions and waves. The mathematics of the extended prediction technique is described and results are illustrated by presenting typical vortex-induced responses for single-tube risers. The results of the prediction method are used to highlight the relative magnitudes and nature of vortex-induced response excited by currents, surface vessel motions and waves.

Prediction method of bridge static load test results based on Kriging model

2020 ◽  
Vol 214 ◽  
pp. 110641 ◽  
Author(s):  
Pengzhen Lu ◽  
Zijie Xu ◽  
Yangrui Chen ◽  
Yutao Zhou
Keyword(s):  
Static Load ◽  
Prediction Method ◽  
Kriging Model ◽  
Load Test ◽  
Test Results ◽  
Static Load Test

scholarly journals Research on Lifespan Prediction of Cross-Linked Polyethylene Material for XLPE Cables

2020 ◽  
Vol 10 (15) ◽  
pp. 5381
Author(s):  
Yi Zhang ◽  
Zaijun Wu ◽  
Cheng Qian ◽  
Xiao Tan ◽  
Jinggang Yang ◽  
...  
Keyword(s):  
Operating Time ◽  
Prediction Method ◽  
Hardness Test ◽  
High Accuracy ◽  
Future Research ◽  
Test Results ◽  
Scanning Calorimetry ◽  
Characterization Methods ◽  
Gel Content ◽  
Mechanical And Electrical Properties

In this paper, cross-linked polyethylene (XLPE) cables of the same batch from Factory A, which ran from 1 to 8 years in Jiangsu Province, are sampled. Some widely accepted aging characterization methods of XLPE cables such as the gel content test, differential scanning calorimetry (DSC) test, tensile test and hardness test are employed to obtain the physicochemical, mechanical and electrical properties of the samples. Then, some lifespan prediction parameters significantly correlated with operating time are obtained through correlation calculations. Finally, a prediction method is proposed to predict the operating time of XLPE cables from Factory A. The test results indicate that parameters including the gel content Cge, the crystallinity XC, tensile strength σ, ultimate elongation δ, the dielectric permittivity ε, and the dielectric loss Jtan are significantly correlated with operating time, which can be used in evaluating the aging degree of XLPE cables. Moreover, due to the high accuracy of the experimental verification, it turns out that the lifespan prediction method proposed in this paper can be used to determine the operating time of XLPE cables from Factory A in future research.

A Simple Procedure for the Prediction of the Collapse Pressure of Pipelines With Narrow and Long Corrosion Defects: Uncertainty and Sensibility Analysis

2018 ◽  
Author(s):  
Nara Oliveira ◽  
Theodoro Netto
Keyword(s):  
Simple Procedure ◽  
Experimental Tests ◽  
External Pressure ◽  
Experimental Program ◽  
Small Scale ◽  
Test Results ◽  
Collapse Pressure ◽  
Operational Conditions ◽  
Sensibility Analysis ◽  
Corrosion Defects

The collapse pressure of pipelines containing corrosion defects is usually predicted by deterministic methods, either numerically or through empirical formulations. The severity of each individual corrosion defect can be determined by comparing the differential pressure during operation with the estimated collapse pressure. A simple deterministic procedure for estimating the collapse pressure of pipes with narrow and long defects has been recently proposed by Netto (2010). This formulation was based on a combined small-scale experimental program and nonlinear numerical analyses accounting for different materials and defect geometries. However, loads and resistance parameters have uncertainties which define the basic reliability problem. These uncertainties are mailyrelated to the geometric and material parameters of the pipe and the operational conditions. This paper presents additional experimental tests on corroded pipes under external pressure. The collapse pressure calculated using the equation proposed by Netto (2010) is compared with this new set of experiments and also with test results available in open literature. These results are used to estimate the equation uncertainty. Finally, a sensitivity analysis is performed to identify how geometric parameters of the defects influence the reduction of collapse pressure.

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