The use of sacrificial anodes to provide cathodic protection in the marine and offshore environment is very common. They come in various shapes and sizes; they may be flush-mounted, stand-off or bracelet and are commonly manufactured in either zinc or aluminium. When new they look shiny and are easily distinguishable from the structure they are designed to cathodically protect. But after a period of operation their form can become obscured.
The Question
Are the sacrificial anodes functioning as designed?
The Challenge
Sacrificial anodes are often located in places that make inspection difficult and expensive. With divers or ROVs, inspection is limited to visual estimation of anode depletion and CP measurements. Anode corrosion products, marine growth and water visibility add to the challenges.
The Fix
If the opportunity presents itself, get in there and physically examine the anode. Corrosion product can be removed and examined, the anode surface morphology can be checked for uniform depletion, accurate dimensions taken for true weight loss and electrical continuity confirmed. A much more accurate estimation of anode remaining life and/or retrofit requirements can be presented.
Subsea Corrosion engineers have the qualifications and experience to conduct this type of sacrificial anode examination. Guidance and recommendations on anode remaining life and retrofit requirements can be provided, giving owners and operators peace of mind that their structures are cathodically protected. Inspection intervals can be increased and retrofit costs reduced.
