0

Full Content is available to subscribers

Subscribe/Learn More  >

The Effect on Dynamic Steel Tube Umbilical Fatigue Performance Associated With Designing for Elevated Temperature

[+] Author Affiliations
Jamie Fletcher-Woods, Jake Noble, Lewis Balfour

Technip Umbilicals Ltd, Newcastle Upon Tyne, UK

Paper No. OMAE2017-61895, pp. V05AT04A027; 7 pages
doi:10.1115/OMAE2017-61895
From:
  • ASME 2017 36th International Conference on Ocean, Offshore and Arctic Engineering
  • Volume 5A: Pipelines, Risers, and Subsea Systems
  • Trondheim, Norway, June 25–30, 2017
  • Conference Sponsors: Ocean, Offshore and Arctic Engineering Division
  • ISBN: 978-0-7918-5769-4
  • Copyright © 2017 by ASME

abstract

The expansion of umbilical functionality to include power cables and high temperature fluid transportation (for applications such as gas lift) has led to the requirement for a high temperature steel tube riser umbilical, as shown in Figure 1. The combination of the elevated temperature and the dynamic service conditions create a unique design brief for steel tube umbilicals.

The following paper presents a case study evaluating a steel tube riser umbilical capable of transporting hot gas at 70°C from an FPSO to a well head at approximately 800m water depth. The material selection for the steel tube is super duplex stainless steel (SDSS) and due to the high temperature, the corrosion resistant coating selected to ensure corrosion resistance in seawater at 70°C is fusion bonded epoxy protected with a bonded polypropylene outer layer (3LPP).

The fatigue performance of the dynamic steel tube umbilicals is highly dependent on the frictional loads between the components developed due to tension and bending. This loading is most critical in the bend stiffener location at the riser umbilical’s interface with the FPSO structure. The fatigue critical component is usually determined to be one of the super duplex steel tubes within the umbilical.

The frictional loads are a function of the coefficient of friction between the interacting components and the contact load developed between the layers of helically wound components. This contact load increases with tension.

The paper considers the effects of the polypropylene material selection and the elevated operating temperature on the friction interface between the steel tubes. The work assesses the corresponding change in fatigue damage through the service life in comparison to more common temperatures and materials used in dynamic steel tube umbilicals.

Changes in contact load between elements of a friction interface are known to affect the friction coefficient. The contact load across all interfaces has been varied to help understand how the coefficient of friction may be affected by different tensile loads or umbilical designs. Including this variable in the test program also ensures that the friction is quantified at a contact load relative to the design case considered.

To assess the differences in friction a scope of component level friction testing is presented and the results are processed through umbilical local fatigue analysis software to establish the implications on fatigue performance.

The umbilical structure is designed to free flood in between the components in service, and the bend stiffener region is submerged for the design case in question. Full scale flex-fatigue testing of the dynamic umbilical and the bend stiffener are however conducted in a dry environment. The impact of this on the severity of the test and in comparison to the in-service condition are assessed using component level wet and dry testing to provide changes in friction for sensitivity analysis.

In addition to the loading on the tubes, the fatigue performance of the material being loaded is also considered. the fatigue performance of welded super duplex tubing has previously been tested and documented at ambient room temperature conditions and therefore the effect on the welded steel tube fatigue performance due to the increase in temperature for this application has been quantified to ensure the proposed design curve is suitable. cyclic bending stress experienced by the steel tubes during dynamic service (2).

Copyright © 2017 by ASME

Figures

Tables

Interactive Graphics

Video

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

NOTE:
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