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Laboratory and Numerical Study of External Corrosion Effect on the Integrity of Sea Pipelines

Afzalimir, Hamidreza | 2018

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 51543 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Raie, Mohamad
  7. Abstract:
  8. This research evaluates the effect of external corrosion geometry and bending moment on the burst pressure of pipes. In recent decades, the use of natural resources of offshore oil and gas has increased, as a result, the use of offshore pipelines for transferring products has grown dramatically. At the same time, numerous accidents and explosions in offshore pipelines and its economic and environmental consequences indicates the importance of ensuring safe operation. Pipeline Integrity Management has been developed to ensure safe and efficient operation of pipelines. Integrity management includes planning, inspection, evaluation and repair. This cycle is checked continuously. The importance of integrity evaluation is high due to the complexity of the analysis. In sea pipelines, due to the corrosive environment and high internal pressure, bursting is one of the main incidents. In this regard, some equations are presented by guidelines and codes to assess the burst pressure. Also, these equations do not cover some actual circumstances. For example, do not take into account some of loads, such as tensile axial force, while in practice it happens between the periodic repairs of the pipe. In addition, equations in some combinations of loading provide incorrect and non-conservative results. The bending moment can occur along the pipelines at different points. The most common place is free spans. Also, due to accidents such as anchoring of vessels, the pipelines may be subjected to bending moment in addition to operating loads. In this regard, for pipelines that integrity assessment is necessary due to corrosion defects, bending moments are of great importance. In this research, the finite element analysis and small scale laboratory tests have been used to investigate the effect of corrosion geometry and bending moment on the burst pressure. The results indicate that bending moment in pipes with groove shape corrosions lead to burst pressure reduction. Finally, a procedure for evaluating the burst pressure of pipes with groove shape corrosion under bending moment is presented
  9. Keywords:
  10. Subsea Pipeline ; Pipelines ; Integrated Management ; Burst Pressure ; Finite Element Analysis ; Bending Moment ; Experimental Test ; Free Span

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