Commercial and Industrial Tanks - Galvanic Corrosion (Dissimilar Metal Corrosion)

So far this year our Field Service Technicians have been extremely busy carrying out Service Work and Tank Inspections across Australia. Our Inspections & photographic reports are performed while a tank is either empty or full, and using one of our ROV’s and reporting apps.

Recently, Kingspan Technicians were chosen to inspect a square steel tank which had structurally failed. The tank was situated at high level inside a building in a CBD. The failure caused damage extending beyond the vicinity of the tank and to many floors of the building. Fortunately, there were no injuries or casualties. ?

Kingspan identified various contributions to the reasons behind the failure however, the main cause was structural work had been compromised by Galvanic corrosion. It is all too often we encounter this form of corrosion inside storage tanks. It can also be saddening to inspect tanks which are at risk of failure or tanks which have not been maintained when ultimately, the servicing of the tank could prevent catastrophic results and also increase the asset life expectancy.???

Galvanic corrosion which is also referred to as ‘’Dissimilar Metal Corrosion’’ is not selective and affects Tanks used for Fire, Sprinkler, Hydrant, Potable, or other Tank applications.

Galvanic Corrosion occurs when two or more metals in electrical contact are placed in an electrolyte. This forms a potential difference between the metals which causes current to flow between them. The more noble metal becomes cathodic while corrosion takes place at the more active metal.

It is surprising how many tanks our trained technicians encounter which suffer from early or advanced stages of corrosion. Some of the site types where we see corrosion include Warehouses, Hotels, Schools, and Hospitals. Galvanic corrosion is its own specialist topic with many factors contributing to the rate of corrosion.?

For Kingspan, the most common type of corrosion we encounter is from the tank's internal components (brackets, nozzles, ladders, struts, stays and seismic restraints) being manufactured and installed with differing metals which are not compatible especially under submerged conditions and with no isolation.

Correct tank material choice, an approved Quality Management System and the right tools for installation will prevent Galvanic Corrosion. We recommend, for the purposes of insurance, warranty and compliance, existing tank owners engage a specialist to perform routine service, maintenance, and inspections of your asset.

Inspections after commissioning and inspections at the manufacturer's recommended intervals will help detect corrosion early. In return, this allows preventative measures to be put in place and reduce the risk of failure.

If you have a requirement for service, maintenance, or inspection, please contact us [email protected]