Reliability analysis of marine risers with narrow and long corrosion defects under combined loads

A marine riser, one of the most important components of offshore oil/gas transportation, needs to be designed to eliminate the risks caused by complex ocean environments, platform displacement and internal corrosion, etc. In this study, a new analytical-numerical assessment approach is proposed in order to quantitatively investigate the reliability of internally corroded risers under combined loads including axial tension and internal pressure. First, an analytical solution of the limit state function of intact risers under combined loads is obtained, which is further modified by the non-dimensional corrosion depth (d/t) for the risers with a narrow and long corrosion defect. The relationship between d/t and limited internal pressure is obtained by finite element analysis and nonlinear regression. Through an advanced first-order reliability method (HL-RF) algorithm, reliability analysis is performed to obtain the failure probability, the reliability index and the sensitivity. These results are further verified by Monte-Carlo importance sampling. The proposed approach of reliability analysis provides an accurate and effective way to estimate the reliability of marine risers with narrow and long corrosion defects under combined loads.

[1]  Kamel Chaoui,et al.  Reliability assessment of underground pipelines under the combined effect of active corrosion and residual stress , 2006 .

[2]  R. Rackwitz,et al.  Structural reliability under combined random load sequences , 1978 .

[3]  C. Guedes Soares,et al.  Reliability of pipelines with corrosion defects , 2008 .

[4]  M. Modarres,et al.  Reliability Analysis for Degradation Effects of Pitting Corrosion in Carbon Steel Pipes , 2011 .

[5]  Luca Campioni,et al.  Monte Carlo importance sampling optimization for system reliability applications , 2004 .

[6]  F. M. Burdekin,et al.  Engineering critical analyses to BS 7910 — the UK guide on methods for assessing the acceptability of flaws in metallic structures , 2000 .

[7]  Wenxing Zhou,et al.  System reliability of corroding pipelines , 2010 .

[8]  Markus R. Dann,et al.  Influence of grade on the reliability of corroding pipelines , 2008, Reliab. Eng. Syst. Saf..

[9]  Francisco Caleyo,et al.  A study on the reliability assessment methodology for pipelines with active corrosion defects , 2002 .

[10]  Michael Smith.  Fitness for Service, API 579-1/ASME FFS-1 , 2007 .

[11]  A. M. Hasofer,et al.  Exact and Invariant Second-Moment Code Format , 1974 .

[12]  L. M. Berliner,et al.  Approximate importance sampling Monte Carlo for data assimilation , 2007 .

[13]  R. Levine.  Monte Carlo, maximum entropy and importance sampling , 1998 .

[14]  Y. H. Chai,et al.  Assessment of the flexural capacity of corroded steel pipes , 2010 .

[15]  Terje Haukaas,et al.  Feasibility of FORM in finite element reliability analysis , 2010 .

[16]  Brian N. Leis,et al.  Strength Criteria And Analytic Predictions of Failure Pressure In Line Pipes , 2004 .

[17]  P Willems,et al.  Probabilistic modelling of overflow, surcharge and flooding in urban drainage using the first-order reliability method and parameterization of local rain series. , 2008, Water research.

[18]  D. Lomario,et al.  A comparison between Monte Carlo and FORMs in calculating the reliability of a composite structure , 2003 .

[19]  J. Rice.  Mathematical Statistics and Data Analysis , 1988 .

[20]  Xin Li,et al.  Burst Capacity Solutions For Submarine Pipeline With Long Corrosion Defects , 2008 .

[21]  W. Kent Muhlbauer,et al.  Pipeline Risk Management Manual , 1992 .

[22]  Robert E. Melchers,et al.  Reliability estimation of pressurised pipelines subject to localised corrosion defects , 1996 .

[23]  Segen F. Estefen,et al.  The effect of corrosion defects on the burst pressure of pipelines , 2005 .

[24]  G. Cheng,et al.  Convergence analysis of first order reliability method using chaos theory , 2006, Computers & Structures.

[25]  D. R. Stephens,et al.  An Alternative Approach to Assess the Integrity of Corroded Line Pipe - Part II: Alternative Criterion , 1997 .

[26]  Ibrahim Khairul Anwar,et al.  The effect of corrosion defects on burst pressure of pipelines , 2012 .