The failure mode of bellows could be any of a variety of things including erosion, corrosion, cyclic fatigue or thermal creep at elevated temperatures.
![Failed expansion joint](https://usbellows.com/wp-content/uploads/1990/07/failed-expansion-joint-300x169.jpg)
The failure mode of bellows could be any of a variety of things including erosion, corrosion, cyclic fatigue or thermal creep at elevated temperatures.