E-Thesis 282 views 833 downloads
Mechanical Properties of Vintage Seam-Welded Pipe / CARRIE PRESCOTT-TAGG
Swansea University Author: CARRIE PRESCOTT-TAGG
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Copyright: The author, Carrie Brisbane Prescott-Tagg, 2025
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Abstract
In the transition from fossil fuels to hydrogen, understanding the conditions and limitations of the pipelines that are currently in operation is important. Pre-1970s pipelines were designed before the development of current pipeline standards, and its data were not well-documented. Previously, vint...
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Swansea University, Wales, UK
2025
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| Institution: | Swansea University |
| Degree level: | Master of Research |
| Degree name: | MSc by Research |
| Supervisor: | Sacket, E., and Rudd, T. |
| URI: | https://cronfa.swan.ac.uk/Record/cronfa70084 |
| Abstract: |
In the transition from fossil fuels to hydrogen, understanding the conditions and limitations of the pipelines that are currently in operation is important. Pre-1970s pipelines were designed before the development of current pipeline standards, and its data were not well-documented. Previously, vintage girth welds were tested and characterised, but there was still a knowledge gap regarding vintage seam welds.Therefore, the purpose of this thesis was to characterise a section of vintage seam-welded gas pipe, determining their suitability to ongoing operation by testing and comparing weldment and parent metal from a section of pipe with modern weld quality and fatigue standards.The section of pipe tested was identified as buried vintage API 5L X52 mechanically electric-resistance-welded gas pipe and adhered to PSL-1. Four samples of the parent metal and two centred about the weld were extracted for testing.Within a weldment sample, four broad main regions were identified: the weld-line, coarse-grain heat-affected zone, fine-grain heat-affected zone, and parent metal. Through microhardness testing, all measured values fell under the maximum allowed value. The weld was the region of lowest hardness, and the fine-grain heat-affected zone was the region of greatest hardness. The samples endured fatigue testing that exceeded the minimum yield stress value for PSL-1, and a minimum of 150 years' worth of cycles, with the weldment sample outperforming the parent samples across numerous different stress ranges. The vintage weld sample exceeded a “D-curve” quality based on data from BS 7608. The lack of detected defects through use of NDT methods –ultrasonic phased array, x-ray radiography – suggest the weld-quality meets modern standards, and, despite detecting flaws that the scanning methods did not, the SEM and optical microscopy results still support the suggestion that the vintage pipe section meets the BS 7910 modern weld quality standard at a Q4 level. |
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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: |
Vintage, seam, seam-welded, pipeline, steel, HAZ, X52, fatigue, characterisation |
| College: |
Faculty of Science and Engineering |
| Funders: |
UK Shared Prosperity Fund via the UK Government and Neath Port Talbot Council, UKOPA (the United Kingdom Onshore Pipeline Operators’ Association) |