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Eddy current detection of fatigue cracks in drill pipes
Includes abstract.
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| Other Authors: | |
| Format: | Thesis |
| Language: | English |
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Department of Mechanical Engineering
2014
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| _version_ | 1867613328608591874 |
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| access_status_str | Open Access |
| author | Molteno, Matthew Robert |
| author2 | Tait, Robert B |
| author_browse | Molteno, Matthew Robert Tait, Robert B |
| author_facet | Tait, Robert B Molteno, Matthew Robert |
| author_sort | Molteno, Matthew Robert |
| collection | Thesis |
| description | Includes abstract. |
| format | Thesis |
| id | oai:open.uct.ac.za:11427/6084 |
| institution | University of Cape Town (South Africa) |
| language | eng |
| last_indexed | 2026-06-10T12:34:23.309Z |
| license_str | Not specified — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UCTD — University of Cape Town Open Access Repository |
| publishDate | 2014 |
| publishDateRange | 2014 |
| publishDateSort | 2014 |
| publisher | Department of Mechanical Engineering |
| publisherStr | Department of Mechanical Engineering |
| record_format | dspace |
| source_str | UCTD — University of Cape Town Open Access Repository |
| spelling | oai:open.uct.ac.za:11427/6084 Eddy current detection of fatigue cracks in drill pipes Molteno, Matthew Robert Tait, Robert B Wilkinson, Andrew John Becker, TH Mechanical Engineering Includes abstract. Includes bibliographical references. The Vertical Marine Mining technique is a lucrative method used by De Beers to recover bottom lying diamonds from the seabed, mainly off the coast of Namibia. The method employs a 200m length pipe-drilling structure rotated from the surface and acting as a conduit through which the disturbed sediment is transported to the surface for processing. However, cyclic operating stresses combined with corrosion have tended to cause circumferential fatigue cracks to develop on the outside surface of the drill pipe and propagate inwards. As no early warning system exists, these cracks propagate undetected until failure occurs. High operational costs and losses associated with down time, provide a strong motivation for a system to detect fatigue cracking prior to failure, especially given that fatigue crack growth rate and fatigue lifetimes can be estimated using Fracture Mechanics principles. Therefore what is required is an early warning of fatigue crack initiation with non-destructive testing (NOT). The eddy current method is an ideal NDT technique as it does not require contact with the test surface and is highly sensitive to fatigue cracks .. However, this method is generally only sensitive to surface and near surface defects. This proves to be a major limitation - the external drill pipe surface is obstructed by flanges and fittings such that continuous inspection of the external surface would be impossible. Therefore two specialised eddy current methods to allow the detection of external fatigue cracks from inside the drill pipe were reviewed, namely: Pulsed Eddy Current (PEC) and Remote Field Eddy Current (RFEC). It was found that unlike PEC, RFEC is highly sensitive to external circumferential planar defects in ferrous pipes. This, above all, highlighted the suitability of RFEC for drill pipe inspection. 2014-08-13T13:24:30Z 2014-08-13T13:24:30Z 2012 Master Thesis Masters MSc http://hdl.handle.net/11427/6084 eng application/pdf Department of Mechanical Engineering Faculty of Engineering and the Built Environment University of Cape Town |
| spellingShingle | Mechanical Engineering Molteno, Matthew Robert Eddy current detection of fatigue cracks in drill pipes |
| thesis_degree_str | Master's |
| title | Eddy current detection of fatigue cracks in drill pipes |
| title_full | Eddy current detection of fatigue cracks in drill pipes |
| title_fullStr | Eddy current detection of fatigue cracks in drill pipes |
| title_full_unstemmed | Eddy current detection of fatigue cracks in drill pipes |
| title_short | Eddy current detection of fatigue cracks in drill pipes |
| title_sort | eddy current detection of fatigue cracks in drill pipes |
| topic | Mechanical Engineering |
| url | http://hdl.handle.net/11427/6084 |
| work_keys_str_mv | AT moltenomatthewrobert eddycurrentdetectionoffatiguecracksindrillpipes |