The type and speed of corrosion is attributed to several different physical and chemical factors. The first stage of corrosion usually involves pinhole leaks in the water pipes. The leaks increase in frequency to the point that a shut down to repair one leak will create further leaks.

GENERAL SURFACE CORROSION
Always present but the least damaging. It forms a low-level attack against the entire metal surface with very little, if any, localized penetration. It results in rust deposits but rarely in damage.

PITTING CORROSION
Localized with deep penetration of the entire metal surface, pitting has little general corrosion in the surrounding areas. On the metal surfaces that are in direct contact with water, it has pin-like scratches and a rough surface profile.

GALVANIC/CONTACT CORROSION
A very aggressive and localized form of corrosion that is usually caused by an electrochemical reaction between two dissimilar metals in a conductive environment. Eg: copper and steel piping.

EROSION CORROSION
Attributed to entrained air bubbles, suspended solids and particulates under a flow rate of sufficient velocity, it is the gradual deterioration of the metal surfaces due to mechanical wear and abrasion.

CORROSION UNDER INSULATION (CUI)
Accumulated moisture to the point of water-logging, it is a major threat to any piping system operated at lower temperatures in a humid environment. Moisture will penetrate the barrier
and/or protective coating and condense at the cold metal surface.