Residual Strength of Corroded Pipelines Under External Pressure: A Simple Assessment

Abstract

The loss of metal in a pipeline due to corrosion usually results in localized pits with various depths and irregular shapes on its external and internal surfaces. The effect of corrosion defects on the collapse pressure of offshore pipelines was studied through combined small-scale experiments and nonlinear numerical analyses based on the finite element method. An extensive parametric study using 2-D and 3-D numerical models was carried out encompassing different defect geometries and their interaction with pipe ovalization. This paper briefly summarizes these results, which are subsequently used to develop a simple procedure for estimating the collapse pressure of pipes with narrow defects.

Residual ultimate strength of offshore metallic pipelines with structural damage – a literature review

“…Metal loss is a generalised kind of structural damage that involves partial loss of material in the form of gouges, notches, etc. Research such as Fu and Kirkwood (1995), Loureiro et al (2001), Kim et al (2002), Benjamin and Andrade (2003), Netto et al (2006), and has been conducted on the effect of single metal loss damage. Specifically, investigated the residual bending capacity of pipelines with corrosion-induced metal loss on a pipe's internal surface, where the internal pressure and axial tension force were prescribed in advance.…”

“…Buckling-induced collapse can occur when pipelines are subject to external pressure. Considerable test research such as Dyau and Kyriakides (1993), Park and Kyriakides (1996), Gresnigt et al (2000), Bruschi et al (2005) and Netto et al (2006) has been done on such collapse capacity of pipelines. A typical set-up for pipe external pressure test can be seen in Figure 7(b).…”

“…Meanwhile, the bending moment exists extensively in pipes. For instance, pipes are exposed to a large bending moment when they are leaving a barge during the pipe installation phase (Gresnigt et al 2001;Vitali et al 2005;Netto et al 2006;Hilberink 2011;. The manufacturing process is an another factor that has a considerable effect on pipe strength.…”

“…To investigate the strength of pipeline structures, research methodologies are typically categorised into experimental tests, numerical simulations and analytical predictions. Experiments from the literature such as Dyau and Kyriakides (1993), Fu and Kirkwood (1995), Park and Kyriakides (1996), Lancaster and Palmer (1996a), Gresnigt et al (2000), Bjørnøy et al (2000), Gresnigt et al (2001), Loureiro et al (2001), Kim et al (2002), Benjamin and Andrade (2003), Vitali et al (2005), Bruschi et al (2005), Netto et al (2006), Hilberink (2011), , , Polenta et al (2015) and Zhang et al (2015) have been carried out. When tests are not available, a good alternative is the FEM (finite element method), which has been extensively deployed by researchers and recognised as a powerful tool that can provide accurate prediction of structure strength.…”

“…Some so-called 'numerical laboratories' for predicting pipe strength have been developed by research groups (Bruschi et al 2005;Vitali et al 2005;Gresnigt et al 2007;Bartolini et al 2014). Reliable prediction results have been obtained compared with test results in terms of the shape of buckling modes and the relation between bending moment and curvature (Zhou & Murray 1993;NEB 1994;Bruschi et al 1994;Kirkwood et al 1996;Park & Kyriakides 1996;Batte et al 1997;Loureiro et al 2001;Kim et al 2002;Benjamin & Andrade 2003;Jin & Shao 2004;Bruschi et al 2005;Netto et al 2006;Bartolini et al 2014;Chen et al 2015;Ghaednia et al 2015b). Based on experimental and numerical research, considerable data have been integrated into engineering practice in the form of industrial standards, for instance ASME B31G (ANSI 1991;Szary 2007), Shell 92 (Klever et al 1995), DNV-RP-F101 (DNV 2004), BS7910 (BSI 2005), etc.…”