First I’d just like to go back to last month’s article. Due to a technical error (I will not apportion blame but let us say it was 50-50!) the picture mentioned in the article did not appear. This was the building on the Calke Abbey estate that seemed in need of a bit of TLC from paint and corrosion experts. So I enclose the picture here.

Building on Calke Abbey estate

Also as I was scanning through my files I found another couple of examples of corrosion: not as spectacular as some of the Vulture lectures examples (for those who do not remember these Michael Clark used to go around in the 80s and 90s giving lectures to inter-alia metallurgical societies (always very well attended) showing amusing and in some cases spectacular examples of corrosion); but interesting none the less. Both were taken a couple of years ago in the vicinity of the Grwyne fawr reservoir (1790 feet above sea level) in the Black Mountains.

selective corrosion of barbed wire

The picture of the selective corrosion of the barbed wire could be an illustration of the effect stress has on accelerating corrosion. If one assumes that the thickness of galvanizing on the wire is similar throughout, the reason could be that the stress level is higher where it has been twisted which is why these areas tend to lose their galvanizing first (I am happy to hear alternative explanations!)

picture showing breakdown of the coating

The other picture showing breakdown of the coating is just a typical example where I would suggest the maintenance schedule could be improved (the reservoir was inaugurated in 1923!) . I suppose my approach would be to monitor coating systems like this intermittently using electrochemical methods and repaint them BEFORE they got to that stage. However the main thrust of what I wanted to talk about today relates to a paper that appeared at Eurocorr recently in the microbial session (an area that I must confess that I have not covered in a TT yet, partly because I have no first hand experience of it (although I know Phil Munn reckons it can play a major role in some types of failures in domestic water systems and about ten years ago I did present paper on the subject at the Bath conference for Robert Edyvean (luckily the questions were not too severe!). My latest boss at CEST is also interested in the topic. So I might pluck up the courage to review the subject in a future TT ). Anyway the recent EuroCorr paper was about Accelerated Low Water Corrosion (ALWC) (ref.) which is apparently a quite severe problem and is some way from being totally solved. The author Mr Christie stated that there was a crying need for a coordinated research and explained what he meant by this. Below is a slightly edited version of what he said “What is needed are corroborated and peer-reviewed answers to the remaining un-answered scientific questions. Work has already been done by the engineering fraternity. But to complete the bigger picture, scientists need to get in on the act. One scenario is that answers already exist and the fragments of scientific and microbiological information just need pulling together? To progress this would require some, if not all, of the following: a strong individual, group, or organisation to propel the project; identification of relevant stakeholders: lobbying of the relevant research organizations and lobbying governments or agencies for funding. Additionally requests for sponsorship; identification of contributors; collation and examination of every piece of information, study and research available globally on the science to date; existing knowledge and experience; multi-disciplinary and multi- national input; and strong leadership would be needed. Depending on the outcome, further scientific research may be needed This could require additional funding, organisation and particularly time to conduct field and laboratory studies. Time is of the essence: the longer the delay the longer the present risks (in the case of ALWC these are to the global shipping infrastructure), will remain and the longer we will continue to provide solutions that could be improved on or even be superseded by new and more efficient ones if only we understood the complete picture. Corrosion in general is estimated to cost industry worldwide 150 billion US dollars per annum in lost time, repairs and replacement. So let us work together to do the best we can to keep the ALWC contribution to this figure as low as our capabilities will allow”.

Strong stuff and as I say pretty relevant in quite a number of areas that I can think of (stress corrosion cracking of nuclear boiler tubes , cathodic protection of pipelines, rebar corrosion etc). And probably you readers can think of others!

As usual any comments are welcome and should be sent to:
Douglas@harrbridge.freeserve.co.uk

Douglas Mills - Technical Secretary

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