Predicting Pipeline Collapse Resistance

Abstract

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.

Numerical Simulation of JCO-E Pipe Manufacturing Process and Its Effect on the External Pressure Capacity of the Pipe1

“…It has been shown for the first time that the cold forming of line pipes has a significant effect in determining the level of residual stresses in a line pipe, and should be taken into consideration for the prediction of 1 the ultimate external pressure and pressurized bending capacity. Similar conclusions have been reported in the experimental works [3], [4]. A finite element study has been reported on the effect of UOE cold bending process on the collapse pressure by Herynk et al [5] who employed an advanced two-surface plasticity model using a cyclic-plasticity model with nonlinear kinematic hardening.…”

Numerical simulation of JCO-E line pipe manufacturing and its influence on the mechanical behavior and strength of offsore pipelines

“…It has been shown for the first time that the cold forming of line pipes has a significant effect in determining the level of residual stresses in a line pipe, and should be taken into consideration for the prediction of ultimate external pressure and pressurized bending capacity. Similar conclusions have been reported in the experimental works [9], [10]. A finite element study has been reported on the effect of UOE cold bending process on the collapse pressure by Herynk et al [11], employing an advanced two-surface cyclic-plasticity model with nonlinear kinematic hardening.…”

Determination of the Collapse and Propagation Pressure of Ultra-Deepwater Pipelines

“…The dependency of collapse on the sequence of loading is related to the loading/unloading sequences (and resulting material stiffness changes) that arise around the circumference of the pipe cross section. The dependency of collapse on the load path is also discussed in [13] for B---~P and P--~B, as well as for tension plus pressure (T---~P).…”