Runaway Linear Cracking

Runaway Linear Cracking

• A. A slow corrosion process.
• B. A puncture due to impact.
• C. When a container is stressed and weakens due to metal fatigue; internal pressure exceeds recovery point and results in a rapidly growing crack.
• D. A seal failure due to aging.

Answer: (C)

Runaway linear cracking happens when a container has already been weakened by metal fatigue from repeated stresses, and the internal pressure compounds the problem. The crack tip experiences higher driving force as the vessel is pressurized, so the crack grows faster and in a straight line until the container can’t contain the pressure anymore. This rapid, unstable growth is characteristic of a fatigue crack that reaches a point where the material can no longer resist the load, causing a swift progression toward failure. This is different from slow corrosion, which is a chemical degradation process that progresses gradually over time rather than through crack propagation under pressure. It’s not a puncture from an impact, which would be a sudden, localized hole rather than a fatigue-driven, accelerating crack. It’s also not seal aging, which concerns seals failing over time rather than a crack in the container wall growing due to fatigue and pressure.

Runaway linear cracking happens when a container has already been weakened by metal fatigue from repeated stresses, and the internal pressure compounds the problem. The crack tip experiences higher driving force as the vessel is pressurized, so the crack grows faster and in a straight line until the container can’t contain the pressure anymore. This rapid, unstable growth is characteristic of a fatigue crack that reaches a point where the material can no longer resist the load, causing a swift progression toward failure.

This is different from slow corrosion, which is a chemical degradation process that progresses gradually over time rather than through crack propagation under pressure. It’s not a puncture from an impact, which would be a sudden, localized hole rather than a fatigue-driven, accelerating crack. It’s also not seal aging, which concerns seals failing over time rather than a crack in the container wall growing due to fatigue and pressure.