E-Thesis 401 views 1202 downloads
Weld line Charpy toughness investigations on High Frequency Induction (HFI) welded pipes and exploration of a method to achieve toughness improvements / SAMUEL BAKER
Swansea University Author: SAMUEL BAKER
DOI (Published version): 10.23889/SUThesis.68373
Abstract
The growth of the gas and oil industry into cold regions has driven the demand for high frequency induction welded pipes that are resistant to sour service. However, the toughness of the weld line can deteriorate in cold and harsh environments and producing a weld line that is resistant to these con...
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Swansea University, Wales, UK
2024
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| Institution: | Swansea University |
| Degree level: | Doctoral |
| Degree name: | Ph.D |
| Supervisor: | Pleydell-Pearce, C. |
| URI: | https://cronfa.swan.ac.uk/Record/cronfa68373 |
| Abstract: |
The growth of the gas and oil industry into cold regions has driven the demand for high frequency induction welded pipes that are resistant to sour service. However, the toughness of the weld line can deteriorate in cold and harsh environments and producing a weld line that is resistant to these conditions is challenging since it is already difficult to guarantee acceptable weld line toughness with a sufficiently high level of confidence.Previous research has investigated the factors causing poor toughness. Nonetheless, the research was somewhat limited due to several reasons. The literature has also suggested that a more uniform temperature distribution during welding can improve the weld quality. However, justifications to why have not been determined.This researched aimed to develop a deeper understanding of the factors influencing the toughness of the weld line on a 16 mm thick X60 high frequency induction welded pipe, so subsequent rational could then be developed to establish why a more uniform temperature distribution during welding could improve the weld line toughness. If successful, this knowledge could then be used to develop a method to improve the temperature distribution, and thus enhance the weld line toughness.Characterisation and impact testing established the main factors influencing the toughness of the weld line. It was also discovered that the microstructure varied through the depth of the weld line, where the parts which experienced the greatest heating displayed the most undesirable features for satisfactory toughness. Therefore, it was concluded that by reducing the high temperatures in these regions, the overall microstructure could be improved, subsequently enhancing the toughness of the weld line. With this new knowledge, computational modelling was implemented to explore a method to improve the temperature distribution during welding. This was successful, and achieved by altering the geometry of the strip edges. |
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| Item Description: |
A selection of content is redacted or is partially redacted from this thesis to protect sensitive and personal information. |
| Keywords: |
Welding, toughness, HFI welded pipe, Charpy, high frequency induction welding |
| College: |
Faculty of Science and Engineering |
| Funders: |
Tata Steel, EPSRC & M2A |