Fatigue life analysis of submarine free spanning pipeline

Free spanning could be formed on in-service submarine pipelines. Vortex-induced vibration created by currents waves would lead to fatigue failure of pipelines. Vibration of a submarine pipeline is coupled by piping vibration and vortex wake vibration. On the basis of piping vibration model and Matteoluca vibrator model, dynamic response characteristics of vortex-induced vibration was analyzed. On the base of Miner linear cumulative damage theory and S-N curve method, the fatigue life of a free spanning pipeline was calculated. Recommended measures on prolonging fatigue life of submarine pipelines were given at the end of this article.