|
|
|
|
|
|
| GALVANIC CORROSION | |
|
|
|
|
Technically,
corrosion is the attack and progressive destructions of a metal by means of
a chemical action. Galvanic corrosion, which is characterized by its
destructive power, comes from an electrolysis phenomenon between two metals
of different electrical potential that is in contact and in the presence of
humidity. |
From the desktop of |
Certain metals, “Common” called, are corroded faster than the ones known as “Noble” metals. To the right, there is a list of the most used metals in facilities and marine equipment, in an order from minor to greater degree of galvanic corrosion that they can get to suffer, both in marine water and at room temperature.
|
Since
galvanic corrosion occurs on a variety of different metals, to
avoid it or to diminish it considerably, it is recommended to use metals
of the same type between connections. In case of having different metals
in which there is a water flow, it will be necessary to isolate them one
from the other. When different
metals cannot be isolated, the
metals to use on the union must
be of a nobler metal than the one of the pieces which they hold to,
therefore the corrosion will happen in these ones and not in those of
union.
|
|
|
It is necessary to avoid alloys that contain common metals like brass for example, which lasts very little under the water. The most effective method to resist the galvanic corrosion is protecting all the submerged equipmet or machinery with pure zinc, joining it to the metal to protect or connecting it with a metallic band.
If
you have any suggestions or questions regarding these technical issues,
or if you know someone who's willing to receive these technical letters,
or if you wish to be removed from our mailing list, please send an
e-mail to: technicalletter@ricepropulsion.com |