SEDL / STP / STP1058-EB / STP24092S

Corrosion Fatigue Testing of Welded Tubular Joints Under Realistic Service Stress Histories

Dharmavasan, S
NDE CentreUniversity College London, London,

Kam, JCP
NDE CentreUniversity College London, London,

Dover, WD
NDE CentreUniversity College London, London,

Pages: 19    Published: Jan 1990

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Abstract

Because of the large number of stress cycles experienced by offshore structures in the North Sea, fatigue has become a major design consideration for such structures. Extensive research and testing has therefore been carried out to study the fatigue behavior of offshore structural components, particularly the welded tubular joints.

The laboratory technology for fatigue testing of tubular joints has now progressed to the point where realistic in-service stress history can be used. Crack growth results have been obtained with the use of more realistic load histories, coupled With the effects of the environment.

This paper summarizes some of the progress in the design and simulation philosophy for fatigue testing load histories. The latest crack growth data for welded tubular joints tested under realistic fatigue stress histories, in air and in a corrosive environment, are also presented. In most cases, the crack growth can be predicted reasonably accurately with standard fracture mechanics methodology. However, some unexpected crack growth retardation behavior was also observed, and there is currently no established calculation procedure to predict this phenomenon. Therefore, further studies are required to explain this unusual crack growth feature.