3 of 728 Re: abstract for Eurocorr Inbox x Marcel ROCHE marcel.roche@orange.fr 14:29 (18 hours ago) to me, geiling, j.crouzillac Dear Mr Alexander, We have studied your proposal but we are sorry to inform you that we still cannot understand the scientific background of your paper. In these conditions, we prefer not to select it for this event. For us "the potential of the metal pipeline itself" has no meaning because for corrosion of electrochemical nature we can only refer to the potential of metal in the electrolyte in contact with it, which can be measured only with a "reference" electrode (more or less "perfect"). We do not understand what can be "relative potentials of the earth ". Thank you anyway for your proposal, With our best regards, M. Roche and J. Crouzillac (for EFC WP16) ----- Original Message ----- From: ALEXANDER ROGER To: Marcel Roche Sent: Thursday, March 15, 2012 8:26 PM Subject: Re: Dear Sir's Thank you for your email and I had thought that the contents of the paper itself was sufficient to explain the position with regard to the cathodic protection of pipelines. The standard potential that you mention is used in a laboratory in closed circuit measuring condition but when a copper/copper-sulphate electrode is used in the field it is placed in the electrolyte as one component of the measuring circuit. It has a known potential in itself but is in series with several undefinable potentials one of which was thought to be removed by the 'off potential' method of survey. In order to calculate the potential of the pipeline metal itself, it is necessary to relate it to a fixed potential that is related to other standard electrodes used on other sections of each pipeline system. All cathodic protection surveys that I analyse are considered in this way but I seem to be the only person doing this. The same trouble was encountered with the railway systems in the UK until GMT came into existance to fix a standard zero for measuring time. If we are surveying a pipeline 1000kn long we need to know the relative potentials of the earth along it's path before we can calculate the behaviour of the cathodic ptrotection charges intended to stop corrosion. Because all pipelines are simply conductors embedded in a common electrolyte they form an electrical circuit for which there is at present no zero from which to measure voltages. I have discussed this matter with cathodic protection scientists and practicing engineers globally and thought that your conference would be a good place to kick off the process of getting international organisations such as ISO and the National Physical Laboratory of the UK to agree to a single potential value and position to which all pipeline voltages could be refered. The need is already recognised in Brazil and South Africa and I am circulating the discussion widely on the internet so that by the time of your conference there will be a broad interest. thank you for your interest and I will be pleased to discuss this further Roger Alexander On 15 March 2012 17:39, Marcel Roche wrote: Dear Mr Alexander, My co-chairman Jérôme Crouzillac and myself have made the study of the abstracts proposed for the Cathodic protection session at Eurocorr'2012 Istanbul. You have proposed abstract 1656 on "The need for an international standard electrical potential" and we have to admit that we need clarification on the topics before deciding to accept it, because we do not understand the scientific and/or technical content of the abstract. For us the official reference electrode exists and it is the "Normal Hydrogen Electrode", which is very difficult to use in practice. This is why other more practical electrodes, more or less "perfect", are used depending on the applications. Could you be so kind and explain us what is behind your abstract? Thank you and best regards, Marcel Roche Chairman EFC WP16 ALEXANDER ROGER 16:35 (16 hours ago) to Marcel Dear Sirs, Your decision does not surprise me in the least. I am publishing the paper on the internet where I am getting a wide audience of practicing specialists. The majority reaction has been 'why have we not sorted this out before now?' Each corrosion cell on a pipeline has a common conductor in the pipeline metal and I have demonstration pieces that I use im my lectures to show student how this funtions in the field. Each pipeline is a conductor embedded in the electrolyte that is common with 'remote earth'.I have demonstrated in many countries that switching cathodic protection systems affects all pipelines and electrical flux over an area of thousands of square miles and have simple software to relate all voltages to a common reference potential. The problem is that corrosion committees do not have a common reference potential to make electrical calculations against. The Cu/CuSO4 electrode is merely a ground contact electrode in cathodic protection field work. It is placed in the electrolyte far from the electro-chemical interface that we are tryin to assess. IN THESE CIRCUMSTANCES IT IS NOT A REFERENCE POTENTIAL AGAINST WHICH WE CAN CALCULATE THE VALUES OF OTHER POTENTIALS. ALL GRAPHS PRESENTED TO THE CLIENTS WHO ARE PAYING FOR 'PIPE-TO-SOIL POTENTIALS HAVE A FLOATING ZERO.