Performance of radial fins as a novel upheaval buckling mitigation strategy of subsea pipelines

Abstract

Offshore pipelines, critical for the transport of fluidised fuel from offshore wells to onshore facilities, are often subjected to upheaval buckling due to thermal axial stress. While conventional buckling mitigation techniques are available, they often suffer from case-specific limitations and substantial installation and operational costs. The current study proposes an innovative technique to augment the resistance of pipe segments against uplift buckling through the integration of radial fins, offering a potentially more versatile and cost-effective solution. Fourteen experiments were conducted utilising seven pipe configurations embedded in 13 kPa kaolin clay bed at two different depths. The effects of radial fins on resistance against uplift buckling, pressure encircling the pipe segment, soil surface heaving, and the displacement field within surrounding soil were examined. It was found that uplift resistance of pipe segments was improved by fin integration, with uplift resistance further influenced by suction generation below the pipe segment. An expansion in the soil failure mechanism around fin-integrated pipes was revealed through displacement field obtained using particle image velocimetry, providing insights into uplift resistance for different configurations and embedment depths. The size of this failure mechanism was correlated with uplift resistance, and transitions with varying pipe embedment depth were observed. Based on these results, an optimised pipe configuration was proposed, wherein improved performance was balanced with efficient material usage in production, thus demonstrating the potential of radial fins in the enhancement of offshore pipeline stability.