Characteristics of trawling forces on submarine pipelines by fishing vessel trawl gear

Abstract As vital infrastructure for offshore energy transportation, submarine pipelines face significant safety challenges from fishing vessel trawl operations. This study analyzes towing force characteristics of trawl gear on submarine pipelines to assess their impact on pipeline integrity and provide engineering recommendations. Using DNV-RP-F111 standards and OrcaFlex software, a numerical model was established to simulate trawl-pipeline interactions across various operational stages. Results demonstrate that trawl gear type, pipeline stiffness, end constraints, span height, and seabed properties significantly affect towing forces. The numerical model achieves excellent validation with 1.0% mean relative error compared to DNV-RP-F111 predictions. Key findings include span height as the most influential parameter, flexible pipelines experiencing 21% lower forces than steel pipes, and axial forces reaching 1800 kN in long systems. The study reveals systematic conservatism in current DNV guidelines for long pipeline systems, suggesting opportunities for design optimization. This research provides theoretical foundation and technical support for submarine pipeline design, operation, and maintenance.