Dynamic life prediction method for pressure vessel considering corrosion-fatigue coupling effect

Abstract

In coastal environments, pressure vessels are subjected to the synergistic effect of high humidity/high salt corrosion and alternating loads. The corrosion-fatigue coupling effect makes the damage rate significantly higher than that of a single mechanism, and traditional models cannot accurately describe it. This paper proposes a dynamic life prediction method. First, a three-parameter correction coefficient system is constructed: K1 quantifies the nonlinear acceleration of corrosion rate by salt spray concentration and humidity; K2 integrates salt spray concentration, stress intensity factor amplitude, and pressure fluctuation frequency to optimize the Paris formula; K3 adopts a look-up table method to adapt to inherent risk characteristics of welded cylinders and multi‑layer wrapped vessels. Second, a dynamic fusion mechanism between the model and monitoring data is established. Bayesian updating is used for real‑time parameter calibration, and the remaining life interval estimate (±20%) is output. Finally, the model is verified through calculation examples, historical data backtracking (six‑year crack growth prediction agrees well with measured data), and extreme scenario simulations. The results show that the model has good logical self‑consistency and engineering applicability, providing a quantitative tool for life prediction of in-service pressure vessels in coastal environments.