Corrosion Rate

Corrosion rate is the speed at which a pipeline is losing wall thickness to electrochemical attack, typically expressed in millimetres per year, and it is the number that ultimately determines how long a given defect has before it threatens the pipeline’s pressure-carrying capacity. Corrosion rate is rarely uniform - it depends on soil chemistry, moisture, cathodic protection coverage, and coating condition at each specific location - which is why a single network-average figure is much less useful than location-specific estimates. Two successive measurements of wall loss at the same point, spaced by a known time interval, are what actually let an engineer calculate a real corrosion rate rather than assume one.