Failure analysis of underground pipeline subjected to corrosion

Wang, W 2018, Failure analysis of underground pipeline subjected to corrosion, Doctor of Philosophy (PhD), Engineering, RMIT University.


Document type: Thesis
Collection: Theses

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Title Failure analysis of underground pipeline subjected to corrosion
Author(s) Wang, W
Year 2018
Abstract Underground pipes are essential infrastructure for the transport of water, oil and gas. The presence of localised pitting corrosion has been identified as one of the main deterioration mechanisms for metal pipes. When exposed to external loadings, these corroded pipes can easily fail due to intensified stresses at the corrosion pit. Disruptions to pipelines not only greatly affect the life of citizens, but also cause severe economic loss and pose safety risk. Therefore, accurate prediction of safe design life of buried pipes is significant. The main objective of this research is to investigate the effect of corrosion on the mechanical properties of cast iron pipes. A relatively long-term corrosion test was conducted on cast iron pipe in a corrosive clay soil. The corrosion behaviour of pipes was thoroughly examined using various corrosion techniques. At designated points of time, fracture toughness tests were conducted on single-edge bend specimens that were cut from the pipe wall. The results showed effective outcomes for corrosion behaviour in buried pipes and mechanical properties deterioration. A new three-dimensional geometrical model for sharp corrosion pits is proposed. The domain integral method has been employed, in conjunction with a three-dimensional finite element analysis, to derive the stress intensity factors for pipes. An expression of the maximum stress intensity factors has been developed for corroded pipes and the upcrossing method is employed to quantify the probability of fracture failure. This thesis concludes that both the mechanical properties and microstructure of material are changed due to corrosion. The proposed stochastic model of stress intensity factor can serve as a useful tool to predict the failure of buried cast iron pipes with improved accuracy. This research work will enhance the current knowledge of corrosion and mechanical property degradation of metal pipes and improve estimations of the remaining safe life of buried pipelines.
Degree Doctor of Philosophy (PhD)
Institution RMIT University
School, Department or Centre Engineering
Subjects Construction Materials
Structural Engineering
Civil Engineering not elsewhere classified
Keyword(s) underground pipes
cast iron
soil corrosion
deterioration
fracture
reliability
sharp corrosion pits
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Created: Tue, 27 Nov 2018, 15:13:15 EST by Keely Chapman
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