Magnetic flux leakage (MFL), eddy current (ET) and magnetic reluctance (MR) methods have been combined into one
openable tool to assess the state of both new and used coiled oilfield tubing (CT). The same technologies are also built into
an internal untethered robot that can climb through several miles of piping in refineries, chemical plants and small diameter
installed pipelines. This paper presents some of the results of typical inspections, and the use of fatigue models to assess the
remaining life of the materials.
1. API, API 5ST, Specification for Coiled Tubing, First Edition, American Petroleum Institute, April 2010, Washington, DC.
2. ATEX, “Classification of Places Where Explosive Atmospheres May Occur,” Directive 99/92/EC of the European
Parliament and of the Council, Annex I, 28 January 2000, Brussels, Belgium, p. L 23/61.
3. Dutta, S.M., F.H. Ghorbel and R.K. Stanley, “Dipole Modeling of Magnetic Flux Leakage,” Institute of Electrical and
Electronics Engineers Transactions on Magnetics, Vol. 45, No. 4, 2009, pp. 1959–1965.
4. Dutta, S.M., F.H. Ghorbel and R.K. Stanley, “Simulation and Analysis of Magnetic Flux Leakage,” Institute of Electrical
and Electronics Engineers Transactions on Magnetics, Vol. 45, No. 4, 2009, pp. 1966–1972.
5. McCoy, T., R. Rosine, C. Aulert, J. Martin and R.K. Stanley, “Improved Nondestructive Inspection During Tubing
Manufacture and Servicing,” Proceedings of the Society of Petroleum Engineers/Intervention and Coiled Tubing
Association Conference, Houston, TX, 8–9 April 2003.
6. Stanley, R.K., “An Analysis of Failures in Coiled Tubing,” IADC/Society of Petroleum Engineers Drilling Conference,
3–6 March 1998, Dallas, TX.
7. Stanley, R.K., “Failures in Coiled Tubing,” Fifth International Conference on Coiled Tubing and Well Intervention,
4–6 February 1997, Gulf Publishing, Houston, TX.
8. Stanley, R.K., “Observations on Magnetic Wall Measurements of Coiled Oilfield Tubing,” Materials Evaluation,
Vol. 62, No. 2, pp. 125–128.
9. Stanley, R.K., “Overview of the Nondestructive Inspection Techniques for Coiled Tubing and Pipe,” Materials
Evaluation, Vol. 54, No. 11, 1996, pp. 1245–1250.
10. Stanley, R.K., “Recent Advances in Robotic Tubular inspection,” Insight, Vol., 49, No. 9, 2007.
11. Stanley, R.K., “Results from NDE inspections of Coiled Tubing,” Society of Petroleum Engineers/Intervention and
Coiled Tubing Association Roundtable, Houston, TX, 15–16 March 1998.
12. Stanley, R.K., “Results of Recent Inspections Performed on Coiled Tubing,” Society of Petroleum Engineers/Intervention
and Coiled Tubing Association Roundtable, Houston, TX, 25–26 May 1998.
13. Stanley, R.K., “Testing of Coiled Oilfield Tubing – An Update,” Materials Evaluation, Vol. 58, No. 8, 2000, pp. 970–975.
14. Tipton, S.M., D.W. Moran, C. Chinsethagid and J.R. Sorem, Jr., “Quantifying the Influence of Surface Defects on Coiled
tubing Fatigue Resistance,” Society of Petroleum Engineers/Intervention and Coiled Tubing Association Conference,
Houston, TX, 9–10 April 2002.