Corrosion Fatigue Testing Services

Steel catenary and top tension risers in deep-water oil and gas fields are exposed to corrosive environments on both internal and external surfaces. They are also subject to fatigue as a result of wave-loading, vortex induced vibration, tidal drift, or thermal expansion associated with shutdown and re-start sequences. An aggressive service environment can have a significant effect on the fatigue behaviour of a material or structure, and it then becomes necessary to ensure that appropriate test data are available to quantify the extent to which fatigue performance is degraded.

By its very nature, the subject of corrosion fatigue requires a multi-disciplinary approach to fully understand the processes involved. Environmental factors such as temperature, pH or partial pressure of H 2 S/CO 2 , and mechanical variables such as stress ratio or cyclic frequency can have a significant effect on corrosion fatigue performance. TWI is able to provide an excellent service in this field, by drawing together experts from both its Metallurgy and corrosion and Structural Integrity technology groups.

A range of services is provided to Members in this area, either to single clients, or to Group Sponsored or Joint Industry Projects. These services include :

Expertise:

  • Corrosion fatigue behaviour of steels, corrosion resistant alloys or clad products.
  • Hydrogen embrittlement or Hydrogen Induced Cracking.
  • Stress Corrosion Cracking, Sulphide Stress Corrosion.
  • Testing and Evaluation - Determination of endurance data (S-N curves) or fatigue crack growth rates in air or simulated service environments.

Facilities:

  • Computer controlled servo-hydraulic testing machines with environmental chambers for both endurance and fatigue crack growth rate testing, in aqueous solutions at elevated temperature and/or pressure.
  • Fatigue testing in sour or sweet brines at controlled pH, H 2 S/CO 2 content and low dissolved oxygen (<10ppb).
  • Fatigue testing in seawater with or without cathodic protection.

For further information, please contact: oilandgas@twi.co.uk Copyright © 2005 TWI Ltd

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