This Module is very important to everyone involved with the application of cathodic protection because it clarifies the measurement known as 'the pipe-to-soil potential' that is sometimes abreviated to 'PSP'.
The pipe-to-soil potential is quoted in almost all papers and discussions relating to cathodic protection and the control of corrosion to steel pipelines and facilities.
Cathodic Protection has always been divided between the science of electro-chemistry and the application of cathodic protection technology in the field.
The measurement that we require is defined in scientific codes of practice applicable in laboratories where it is possible to control all conditions in a closed measuring circuit.
In cathodic protection work we refer to the working electrode as the ANODE and the return electrode as the CATHODE.
The reference potential in the diagram is the hydrogen electrode and the IR drop is not the voltage drop in the ground that is refered to in cathodic protection field work as 'the IR Drop in the soil'. The IR drop in science is the potential variations that result from the passage of charges from the working electrode to the return electrode.
It can be seen in the diagram that the IR drop between the working electrode and the reference reaction (hydrogen/platignum) is avoided by measuring at the interface between the metal and the electrolyte.
This measurement IS NOT POSSIBLE IN FIELD CONDITIONS without an arrangement of electrodes that is available in the Alexander Cell.
Science requires the codification of repeatedly observable experiments or repeatedly observed events in real life. Science is evidence based.
Engineers must conform to the codified laws of nature or their engineering will fail as it does in applied cathodic protection at present.
Since 1980 cathodic protection data has been stored in computers, but the difference between the electrochemical theory and most basic field practices has made it impossible to achieve computer analysis.
All that is done at presenis to display graphs of voltages and these are interpreted by people who believe that 'protection' has been achieved when a voltage of -0.850v has been measured between a coppr/copper-sulphate ground contact electrode and the electrical contact point with the pipeline, tank bottom or other buried or submerged metal structure.
This module includes practical work that is designed to enable the student to understand how to examine this assumption and form their own opinions about the basic principles that they have been taught.
It is important that each student understands this module as a basis on which they can move forward.
At the end of the course each student will be required to present a paper for publication on the CPN website. The merits of each paper will be assessed by the membership of the CPN.
Experienced corrosion engineers and scientists will be able to check the validity of each step and are encouraged to express their opinions.
This course has been on line for many years now and has had many thousands of visitors.
There are now many interactive students and this page has received over 76,000 hits during this past year.
From discussions on a variety of social and business network groups it can be said that these pages are being used as a sort of reference book but that this is not helping to enhance the practical application of cathodic protection as many asset owners are working to the standards set by NACE and the Institute of Corrosion.
I am now working my way through the course to make it clear that it is essential that students start at the very beginning and do not move on until they thoroughly understand each module.
I have received many reports (as required for a certificate of understanding and ability) and so there are now many of us reviewing other reports that are being submitted.
Software engineers who want to develop diagnostic software for cathodic protection and corrosion control need to understand the laws of nature that apply to our science.
Module 01 is deliberately basic in order to explain the laws of nature that govern us all and to help students to UNDERSTAND the equations that are taught conventionally. We must be able to relate the scientific theories to the actual displays on our instruments and the data that we record on field surveys.