{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,14]],"date-time":"2026-01-14T14:45:18Z","timestamp":1768401918454,"version":"3.49.0"},"reference-count":25,"publisher":"MDPI AG","issue":"1","license":[{"start":{"date-parts":[[2017,1,21]],"date-time":"2017-01-21T00:00:00Z","timestamp":1484956800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["51505308"],"award-info":[{"award-number":["51505308"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["51175356"],"award-info":[{"award-number":["51175356"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["51475194"],"award-info":[{"award-number":["51475194"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100012226","name":"Fundamental Research Funds for the Central Universities","doi-asserted-by":"publisher","award":["2015SCU11059"],"award-info":[{"award-number":["2015SCU11059"]}],"id":[{"id":"10.13039\/501100012226","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100004543","name":"China Scholarship Council","doi-asserted-by":"publisher","award":["201606245039"],"award-info":[{"award-number":["201606245039"]}],"id":[{"id":"10.13039\/501100004543","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>To meet the great needs for MFL (magnetic flux leakage) inspection of drill pipes at wellheads, a lift-off-tolerant MFL testing method is proposed and investigated in this paper. Firstly, a Helmholtz coil magnetization method and the whole MFL testing scheme are proposed. Then, based on the magnetic field focusing effect of ferrite cores, a lift-off-tolerant MFL sensor is developed and tested. It shows high sensitivity at a lift-off distance of 5.0 mm. Further, the follow-up high repeatability MFL probing system is designed and manufactured, which was embedded with the developed sensors. It can track the swing movement of drill pipes and allow the pipe ends to pass smoothly. Finally, the developed system is employed in a drilling field for drill pipe inspection. Test results show that the proposed method can fulfill the requirements for drill pipe inspection at wellheads, which is of great importance in drill pipe safety.<\/jats:p>","DOI":"10.3390\/s17010201","type":"journal-article","created":{"date-parts":[[2017,1,23]],"date-time":"2017-01-23T10:40:33Z","timestamp":1485168033000},"page":"201","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":36,"title":["A Lift-Off-Tolerant Magnetic Flux Leakage Testing Method for Drill Pipes at Wellhead"],"prefix":"10.3390","volume":"17","author":[{"given":"Jianbo","family":"Wu","sequence":"first","affiliation":[{"name":"School of Manufacturing Science and Engineering, Sichuan University, Chengdu 610065, China"}]},{"given":"Hui","family":"Fang","sequence":"additional","affiliation":[{"name":"School of Manufacturing Science and Engineering, Sichuan University, Chengdu 610065, China"}]},{"given":"Long","family":"Li","sequence":"additional","affiliation":[{"name":"School of Mechanical Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China"}]},{"given":"Jie","family":"Wang","sequence":"additional","affiliation":[{"name":"School of Manufacturing Science and Engineering, Sichuan University, Chengdu 610065, China"}]},{"given":"Xiaoming","family":"Huang","sequence":"additional","affiliation":[{"name":"School of Manufacturing Science and Engineering, Sichuan University, Chengdu 610065, China"}]},{"given":"Yihua","family":"Kang","sequence":"additional","affiliation":[{"name":"School of Mechanical Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China"}]},{"given":"Yanhua","family":"Sun","sequence":"additional","affiliation":[{"name":"School of Mechanical Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3749-947X","authenticated-orcid":false,"given":"Chaoqing","family":"Tang","sequence":"additional","affiliation":[{"name":"School of Electrical and Electronic Engineering, Newcastle University, Newcastle upon Tyne NE1 7RU, UK"}]}],"member":"1968","published-online":{"date-parts":[[2017,1,21]]},"reference":[{"key":"ref_1","first-page":"4","article-title":"Corrosion in the oil industry","volume":"6","author":"Brondel","year":"1994","journal-title":"Oilfield Rev."},{"key":"ref_2","unstructured":"API (American Petroleum Institute) (2002). 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