Structure-To-Sea Water Potentials

Buckleys provide a range of sub-sea corrosion monitoring equipment specifically designed to measure the structure to sea water potential of immersed structures.

The BathyCorrometer ® Pro' , UCP1A, UCP1B, and marine type silver/silver chloride half-cell all contain a silver/ silver chloride sea water electrode. The structure to sea water potential is always with respect to the silver/silver chloride sea water electrode.

From a measurement of the structure to sea water potential an indication of the corrosion status of a given structure can be obtained. The structure to sea water potential will give an indication of whether a structure is corroding or is partially or fully cathodically protected.

This indication will be provided by the actual value of the potential displayed on the measuring device. If the potential value recorded indicates that the structure is corroding then only the likelihood of corrosion can be determined as measurement of the structure to sea water potential will not give information on the rate of corrosion but will provide an indication as to whether corrosion is likely. Guidance on the significance of the value of the structure-to-sea water potential versus a silver/silver chloride sea water electrode is given on the BathyCorrometer ® Guidance chart.

Additional guidance on the structure to sea water potentials necessary to achieve cathodic protection on different structures can be obtained from EN 12473.

The Buckleys BathyCorrometer ® Pro' is constructed with the internal reference electrode connected to the negative terminal of a millivoltmeter.

Thus, a cathodically protected potential displayed on the BathyCorrometer ® Pro' millivoltmeter will be shown as -0.800V; not 0.800V versus Ag/AgCl sea water as shown on the BathyCorrometer ® Guidance chart.

The electrode normally provided with the Buckleys BathyCorrometer ® Pro' is only suitable for use in sea water. Since the reference electrode potential is affected by the chloride concentration in the aqueous environment. If the BathyCorrometer ® Pro' or marine type half cells are to be used in brackish waters, a constant chloride ion activity silver/silver chloride electrode should be used to provide an accurate indication of the structure to sea water potential.