Project Description
Evaluating the resonant behaviour and therefore remaining fatigue life of long pipeline spans to ensure that Vortex-Induced Vibrations (VIV) cannot lead to failure bears a significant cost to offshore industries. The present engineering practice does not
address the presence of marine growth on the pipe, nor its potential to disrupt VIV. However, recent research undertaken by UWA has studied a number of Woodside pipelines (Echo Yodel, Pluto flowlines) and identified a correlation between the extent of marine
growth and the location of pipeline spans. In existing hydrodynamic research, marine growth is treated as longitudinally, temporally and circumferentially uniform in ‘roughness’. However, recent collaborations between marine biologists and subsea engineers within
the Indian Ocean Marine Research Centre have facilitated a greatly enhanced understanding of the nature and influence of marine growth on subsea structures.
Remotely-operated vehicle (ROV) footage of Echo Yodel was viewed and the marine growth was characterised systematically. Fifteen lengths of pipeline were inspected for each state of the pipeline, including mostly buried, partially buried and spanning.
The prototype concluded that increased marine growth at spans on Echo Yodel causes an increase in hydraulic roughness which is likely to create added pipeline stability and negate the need for costly span-rectification measures. These findings show that postponing costly span-rectification measures is likely to lead to no catastrophic pipeline failure.