CATHODIC PROTECTION OF BURIED TANKS
Cathodic Protection will prevent corrosion on buried or immersed tanks, it supplements the corrosion protection
afforded by the coating system on a tank or pipe, improves tank design life and prevents deterioration of the tank
or pipe. Cathodic Protection will also stop exposure to consequential loss, environmental damage and safety
implications that could follow a leak of petroleum product.
DEFRA Ground Water Protection Code
Section 1.7 states: “Petroleum hydrocarbons are serious
pollutants. Anyone allowing them to pollute groundwater or
surface water risks penalties under the Ground Water
Regulations 1998 and the Water Resources act 1991 along
with significant remediation costs.”
Section 3.17 states: “coatings should not be relied upon as
the sole means of preventing corrosion. Other measures would
include effective leak detection systems and, where appropriate,
cathodic protection.”
Section 4.6 states: “when assessing the risk to groundwater
the authorities would regard the absence of cathodic protection
as a factor that will increase the risk of a leak.”
Section A3.15 discusses methods of assessing corrosion and
states “Assessment of corrosion probability will help to decide
if urgent action is required, e.g. the fitting of cathodic protection,
tank lining or the replacement of a tank.”
What is Corrosion?
There are many specific types of corrosion, but in relation to
UST’s it can be described as electro-chemical corrosion. This
type of corrosion occurs due to the natural amount of electrical
energy in the ground surrounding the UST, and the composition
of the backfill that surrounds the UST. Some environments
are far more corrosive than others, and that is why tanks leak
at different ages.
What is Cathodic Protection?
Cathodic protection is an industrial application that has been
in use since the 1800’s. There are two types of system that
can be utilised on a garage forecourt. A Sacrificial anode
system is utilised on tanks that are electrically isolated from
site, and on new build sites, whilst Impressed current systems
are installed on existing sites that are not isolated. Both of
these systems inhibit external corrosion on tanks, whilst
protecting the structural integrity of the tanks.
Benefits of having Cathodic Protection
- The systems that are incorporated on a UK forecourt such
as wet stock records, strategic monitoring, remote monitoring
and tank testing, are all systems that don’t prevent any thing
happening, they just tell you when it has happened. Cathodic
Protection is a preventative application, which stops the
inevitable deterioration of steel tanks, and the potential
associated costs of petroleum leaks.
- Tanks that have the benefit of Cathodic Protection do not
suffer external corrosion, therefore they do not depreciate
in value, and because of this they contribute to protecting
the overall value of the business.
- Protection from leaks
- Protection from loss of stock
- Reduced exposure to Environmental liability
- Reduced safety liability
