Full Content is available to subscribers

Subscribe/Learn More  >

Measurement of Residual Stress Shakedown in Pressure/Tensile Armour Wires of Flexible Pipes by Neutron Diffraction

[+] Author Affiliations
Upul S. Fernando, Michelle Davidson

GE Oil & Gas, Newcastle upon Tyne, UK

Christopher Simpson, Kun Yan, Mark D. Callaghan, Matthew Roy, John A. Francis, Philip J. Withers

University of Manchester, Manchester, UK

Thilo Pirling

ILL, Grenoble, France

Paper No. OMAE2015-41328, pp. V05AT04A035; 8 pages
  • ASME 2015 34th International Conference on Ocean, Offshore and Arctic Engineering
  • Volume 5A: Pipeline and Riser Technology
  • St. John’s, Newfoundland, Canada, May 31–June 5, 2015
  • Conference Sponsors: Ocean, Offshore and Arctic Engineering Division
  • ISBN: 978-0-7918-5651-2
  • Copyright © 2015 by ASME


The manufacture of unbonded flexible pipes (flowlines and risers) involves wrapping steel wires to create pressure and tensile armour layers. The forming of armour wires from vendor supply conditions to a helix shape on the pipe involves significant plastic straining and the wires that are wrapped onto the pipe are not unloaded. Therefore the armour wires in flexible pipes are expected to contain significant residual stress (RS) as a result of the plastic straining and loading during manufacture and placement. This may lead to detrimental effects on the strength, durability and the service integrity of the pipe. It is postulated that the unfavorable RS introduced during pipe manufacture reduces due to stress shakedown during the factory acceptance test (FAT) where the pipe is subjected to a high internal pressure.

This paper describes the first attempts to measure RS in the armour wires in unbonded flexible pipes. The key development is the use of a neutron diffraction method which allows the measurement of RS in-situ on the manufactured pipe through the whole wire sections. Pipe samples were prepared exposing the relevant metal layer and the measurements were performed on pipe samples taken before and after performing the pressurized FAT. The effect of the FAT on the shakedown of residual stress in pressure armour wires is discussed. As shown by the measurements, the elastic strains and stresses in the pressure armour wires are much larger in the hoop direction of the pipe (i.e. along the length of the wire) than radial or axial to the pipe. In pre-FAT pipe the hoop stresses are essentially tensile on the extrados and compressive on the intrados. The results have shown that the FAT reduces the hoop strains and stresses to approximately 1/3 of their as manufactured level.

Copyright © 2015 by ASME



Interactive Graphics


Country-Specific Mortality and Growth Failure in Infancy and Yound Children and Association With Material Stature

Use interactive graphics and maps to view and sort country-specific infant and early dhildhood mortality and growth failure data and their association with maternal

Citing articles are presented as examples only. In non-demo SCM6 implementation, integration with CrossRef’s "Cited By" API will populate this tab (http://www.crossref.org/citedby.html).

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In