Pipeline Corrosion - Pt 2 (What causes corrosion?)

What causes corrosion

Corrosion is a natural process. The primary driving force of corrosion is based upon the transformation of iron from its natural state to steel.

• Stress corrosion occurs when even a very small pit forms in a metal under stress.
The concentrated stress either deepens and extends the pit, or cracks the protective
film which tends to form. Under continued exposure to the corrosive medium and
stress, the crack extends by alternate corrosion and stress failure.

• Hydrogen embrittlement and hydrogen attack result when atomic hydrogen
penetrates into the grain boundaries of steel producing microcracks, blistering and
loss of ductility. The atomic hydrogen combines into molecules and results in
blistering and laminations.

• Dissimilar soils can effect a buried pipeline, as they will encounter soils that have varying compositions.