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  1. GGedge

    hot dip galvanized bolts forbidden on Stainless Steel vessel?

    Not sure where the project is the OP refers to, but if Eurocodes are ruling standards note this clause from EC3 Design of Steel Structures. A.5 Galvanizing and contact with molten zinc (1) Hot-dip galvanizing of components made of stainless steel is not allowed because contact with molten zinc...
  2. GGedge

    Proper Cleaning/Profiling of Steel Prior to Painting SSPC SP10 vs SP11

    It certainly won't be anything like as clean with SP11 and I doubt it will consistently hit the roughness range. I also imagine that if one is doing a complete bridge it would take a long, long time. Also, remember that the performance of a coating is, to a great extent, determined by the...
  3. GGedge

    HSS corrosion prevention

    "......its pretty benign environment, inside of an air conditioned plant...." In that case the corrosion risk is negligible because the likely time of wetness of the surface will be zero or very close to it. No need to do anything. Cheers GG
  4. GGedge

    Adhesion Test values.

    You could ask Hempel via the contractor if the product (or specification if there is more than one coat) has approval to ISO 12944-6 or 9, atmospheric and offshore respectively. If so ask for the independent test report which should quote adhesion tests before and after accelerated testing...
  5. GGedge

    NACE vs ISO Requirement

    I think you are outside the scope of the corrosivity categories as given in ISO 12944 because of the service temperature. The corrosivity categories given in that standard are the same as those in ISO 9223 which in turn use data from exposure samples up to 28.7 Celsius. I would be inclined to...
  6. GGedge

    NACE vs ISO Requirement

    May seem a minor point but the current version ISO12944 (various dates depending on part) no longer splits the onshore C5 category into M and I sub categories, there is just C5. There is the additional category CX which covers Offshore areas, extreme pollution and humidity, or tropical...
  7. GGedge

    WITHDRAWN STANDARDS AND ITS EQUIVALENT ONES

    For British Standards if you to this site: https://shop.bsigroup.com/ At the top of the page you can search by standard number and the returned list gives the status as current, withdrawn etc. If you click on the link for the page details you get more information, if the standard is withdrawn...
  8. GGedge

    Steel Corrosion Metric?

    That testing might be interesting academically but is of no practical use. Note in relation to the AS table above, the current version of ISO 9223 on which it is based, does not include the T class that is unique to Australia. Also the C5 condition is no longer split but is just C5. Remember...
  9. GGedge

    Steel Corrosion Metric?

    They do, sort of exist, in things like salt spray and accelerated weathering tests. OK for comparing A with B in a standard test or showing the product made today performs the same as that produced a year ago. Predicting what those tests mean on real structures in real service environments...
  10. GGedge

    Steel Corrosion Metric?

    The rate of corrosion is dependent on the service environment, macro and possibly micro, so definition of that is the first step. Cheers GG
  11. GGedge

    Corrosion of stainless steel in the marine splash zone

    There probably are sources out there but I would be wary of extrapolating to a particular situation. Both pitting and crevice corrosion are dependent on the specific exposure conditions. Crevice corrosion in particular can be dependent on the geometry of the crevice. Also there could be an...
  12. GGedge

    How did you become a Materials Engineer?

    By a series of fortuitous accidents. I graduated in the early 1980's with a degree in chemistry, but had no desire to work as a lab rat and in any event the UK was in massive recession so jobs were scarce. I got an opportunity to work for a local Structural Engineer as a sort of office/site...
  13. GGedge

    Corrosion Threshold of Different Stainless Steel Types

    Thanks for clarifying. As both are rather unusual (particularly the second) are there any further details in the public domain? Cheers GG
  14. GGedge

    Corrosion Threshold of Different Stainless Steel Types

    For avoidance of doubt: "I guess that the cases that I have been drug into have been unusual then. The ones that I have seen have had extensive carbonation and were more permeable than they should have been.""I is that referring to stainless steel or carbon steel reinforcement? "I have also...
  15. GGedge

    Corrosion Threshold of Different Stainless Steel Types

    I'm not involved on the modelling aspects, I get dragged in if/when chloride get to the bar and the "what happens?" question. As far as stainless goes the usual answer is not very much at all for any of the steels you listed. The only reason I can think of for using 2205 reinforcement are...
  16. GGedge

    Corrosion Threshold of Different Stainless Steel Types

    Change in pH of concrete occurs due to carbonation (reaction with atmospheric CO2) rather than transport of chloride through the concrete. Typically carbonation is controlled by the concrete cover and mix specification. Corrosion of reinforcement from either de-icing salts or marine environments...
  17. GGedge

    Corrosion Threshold of Different Stainless Steel Types

    I haven't got the papers with me at home, but search for the work of Pedeferri/Bertolini(Milan Polytechnic) and more recently Randstrom (Outokumpu). In summary (from memory) the critical chloride concentration v pH plot shows a significant positive change in slope at high pH (far more than...
  18. GGedge

    Corrosion Threshold of Different Stainless Steel Types

    Assuming non-carbonated concrete the pH of concrete is >12 not near neutral. Assuming chloride concentration is the subject of the original question, for corrosion of reinforcement it is usually expressed as per unit mass of cement or concrete, or as the ratio of chloride to hydroxyl ion...
  19. GGedge

    Corrosion Threshold of Different Stainless Steel Types

    Could you clarify what is meant by corrosion threshold, is it the corrosion loss to cause an effect such as cracking or the chloride concentration to initiate corrosion of the steel?
  20. GGedge

    Materials Engineering x fashion

    I suspect metallurgy won't be much use other than as mentioned by Ed there might be more scope with other materials science stuff. A couple of suggestions, high performance fabrics are big business for things like sports clothing and thus can end up being trendy. Think beyond the likes of...

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