- Title
- Service life prediction of corrosion pitted pipes
- Creator
- Rajabipour, Ali
- Relation
- University of Newcastle Research Higher Degree Thesis
- Resource Type
- thesis
- Date
- 2015
- Description
- Research Doctorate - Doctor of Philosophy (PhD)
- Description
- In this study a Linear Elastic Fracture Mechanics (LEFM) based model is used to estimate the service life of pipes affected by corrosion pitting and influenced by Hydrogen-Assisted Fatigue Cracking. The main idea of the model can be summarised as follows. Firstly, the likely cracking patterns of a hydrogen affected pipe are estimated using the cracking pattern in the equivalent unaffected pipe. Secondly, the failure state of a pitted pipe is defined, based on the state of crack development from the pits. In the third step, the rate of cracking under HA-FC is estimated by reducing the material fracture toughness due to hydrogen diffusion from the crack front. Finally, having available the rate of crack development from the previous step, the location of the crack front is estimated under a HA-FC mechanism and the time required to reach the failure state is estimated. This methodology is novel and is employed herein to predict the service life of pitted brittle material pipes such as cast iron pipes. These are the main focus of this study since they have been used widely in water industry networks. For example, it is estimated that cast iron pipes account for more than 60% of the water mains in UK. In spite of a considerable number of reports on failure of cast iron pipes rigorous approaches to estimating the service life of such pipes have only recently become of research interest. It is anticipated that the present study will contribute to that work. In the last chapter numerical modelling of pipes under increasing axial load and constant internal pressure when there is corrosion pits on the exterior surface of the pipe is reported. It is shown that for the assumed ideal elastic-plastic material the shape and volume of the plastic field depend on pit depth and its geometry. Pipe wall fracture around a pit can be associated with a critical plastic section. The results reported herein should be relevant for estimating of the risk of perforation and of loss of contents for steel pipes under different loading which eventually can be used to estimate the service life time of the corrosion pitted pipes.
- Subject
- pitting corrosion; service life prediction; piplines asset management; hydrogen assisted fatigue cracking
- Identifier
- http://hdl.handle.net/1959.13/1312672
- Identifier
- uon:22448
- Rights
- Copyright 2015 Ali Rajabipour
- Language
- eng
- Full Text
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| Thumbnail | File | Description | Size | Format | |||
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| View Details Download | ATTACHMENT01 | Abstract | 777 KB | Adobe Acrobat PDF | View Details Download | ||
| View Details Download | ATTACHMENT02 | Thesis | 3 MB | Adobe Acrobat PDF | View Details Download |