Burst Tests of Pipeline Containing Colonies of Metal Loss Defects With Different Sizes
- Chenliang Su (Dalian University of Technology) | Ying Li (Zhejiang University of Science and Technology) | Xin Li (Dalian University of Technology)
- Document ID
- International Society of Offshore and Polar Engineers
- The 28th International Ocean and Polar Engineering Conference, 10-15 June, Sapporo, Japan
- Publication Date
- Document Type
- Conference Paper
- 2018. International Society of Offshore and Polar Engineers
- corrosion defects, interaction of defects, steel pipe, failure test, burst pressure
- 0 in the last 30 days
- 26 since 2007
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To study the effect of interaction between colonies of defects on the burst pressure of corroded pipeline, ten experimental cases were designed. Among them, the specimens containing two longitudinal or circumferential aligned defects with different sizes and spacings were fabricated. Burst tests were conducted on the ten tubular specimens. Burst pressures and strains on the surface of defects were measured. The effects of defect sizes and spacings on burst pressures and strains of corroded pipeline were analyzed. Meanwhile, based on the experimental results, the performance of the five interaction rules such as DNV RP F101, API 579, BS 7910, Kiefner and Vieth, Pipeline operator forum (POF) on failure pressure are evaluated.
Due to the harsh environment and the role of aggressive medium, failures of oil/gas transmission pipelines with corrosion defects become of major concern in pipeline integrity management. Wall thinning caused by corrosion on the internal or external surface of the pipelines will result in stress concentration in the pipe wall. Consequently, appropriate residual strength evaluation of corroded pipelines is vitally important. A significant effort over the past 40 years has been made to study the behavior of metal-loss defects of corroded pipeline under static internal pressure using experimental methods.
The failure behavior of a colony of closely spaced defects is much more complex than the failure behavior of an isolated defect. The interaction between adjacent defects has a significant influence on the failure mode and capacity of corroded pipeline with colonies of defects. Burst tests for specimens containing machined irregular or complex-shaped external defects (Freire, Vieira, Castro and Benjamin, 2007) were conducted. Laboratory tests (Benjamin, Freire and Vieira, 2007) were performed with 12 tubular specimens containing groups of interacting defects comprising the combination of two or more base defects. However, for the above tests, the defects comprising the colonies of corrosion had the same size such as length, width and depth. The effect of interaction between colonies of corrosion with different sizes on burst pressure was seldom studied.
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