Abstract: To ensure the safe operation of subsea oil and gas pipelines, and improve the capability of preventing and controlling major accident, in terms of two failure modes of subsea pipelines, penetration and burst, a risk-based early-warning methodology was developed in this paper. Limit state functions were developed for corrosion penetration and burst of pipelines by using the structure reliability theory. The functions were solved by the Monte Carlo method. Then, the dynamic failure probabilities of pipelines were obtained. Through setting the early-warning levels of pipeline failure, the early-warning degree and critical failure years of pipelines were determined. Thus, the early-warning information can be released based on the above procedures. The results show that the failure probability of a pipelines increases with its service time, and it will have a sudden change in its aged stage.The operation safety of pipelines should be paid enough attention at the critical time node and necessary control measures should also be implemented.

Key words: subsea oil &gas pipelines, failure probability, penetration, burst, Monte Carlo method, risk-based early-warning