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Recent content by flames

  1. flames

    Temperature effect of cathodic current density requirement of steel

    Will depend on the corrosion parameters as the a function of temperature. For instance if you are dealing with plain old open-to-atmosphere water than the corrosion rate increases with temperature and then drops off as the oxygen solubility decreases. This would cause your current requirement...
  2. flames

    MEA corrosion

    Check with a process engineer and understand the rich loading and if two phase flow is developing across the exchanger. It wouldn't be uncommon to develop two phase flow on the rich side of the exchanger as the amine is heating up and there is a typical pressure drop across the exchanger. The...
  3. flames

    How must be the anode distribution for a CP in pipelines?

    Your coating efficiency seems a bit low. Is this an older pipeline, designing for a degraded coating, portions not coated, company design standard? We find that most of our coatings (three layer system with corrosion barrier, insulation, outer protective layer) have efficiency >99%, but this...
  4. flames

    How must be the anode distribution for a CP in pipelines?

    In your case you would be likely placing your bed at "remote earth" to provide the current distribution to a long pipeline. You will need to understand the soil resistivities to properly size the anode bed as well as a current test to determine the required current to achieve...
  5. flames

    "Reduction of Corrosion by Capacitive Coupling" ???

    gvh is right, they don't work. On the surface they look good, but they are fundamentally flawed.
  6. flames

    CO2 Corrosion Chart

    H2S charts for corrosion can be found in papers by Sardisco in NACE Corrosion in the 1960's and by Smith in 2001 NACE conference. You can use these sources to cross-reference the other sources that are availible.
  7. flames

    Steel pipe in water for 2 years

    Since your paint is damaged, you must clean the pipe to a clean surface. Your inspection should be fairly easy as you are expecting external corrosion so you can visually inspect the line. Any noticable pits can be measured using a pit gauge. You can use UT to confirm the wall thickness, but...
  8. flames

    Anybody used welded plate heat exchanger in amine system?

    We use welded plates in amine service. The set up is every other gasket is eliminated and replaced with a weld. In this arrangement we have the rich amine between two welded plates (a set) and hot lean amine between the sets of welded plates (contained with a gasket). What we have is severe...
  9. flames

    eddy current results do not correlate

    The biggest error we find in eddy current is due to the operator. We almost always stick with the same guy to do any of our eddy current or remote field eddy current. Like aybee said above, make sure that you have a calibration tube.
  10. flames

    Laboratory equipment material required for testing sour oil

    316SS, as long as it meets NACE 0175, should be just fine for your application. We use C276, but we also are using high concentrations of chlorides and much higher levels of H2S and CO2.
  11. flames

    Lethal Service Criteria

    The company you are designing for and local regulations may dictate your answer. I work in a plant that has pressure >5000kPa total pressure with over 30% H2S and nothing is considered in lethal service.
  12. flames

    Thermal Shock changing material hardness

    The only way to go from a relatively low hardness of annealed 304 to the high hardness that you see is if you go way beyond the yeild strength of the material. You can recheck the design calculations of the exchanger, but hopefully the exchanger was designed so stay well below the yield...
  13. flames

    Failure analysis of Ancient metal artifacts

    You could contact Dr. Wayman at the University of Alberta in Canada (mike.wayman@ualberta.ca) as he specializes in Archaeometallurgy and Historical Metallurgy if you need more help (from the replies to this posting I am not sure you do). He concentrates in various aspects of historical...
  14. flames

    Effects of sour, wet gas corrosion in Carbon Steel Pipelines

    You will get a bunch of different answers to this questions as the mechanisms are not clear. One point I want to make is that although isolated pitting does occur, having an area of corrosion also occurs. Typcially a wet H2S system is not overly corrosive due to the formation of the various...
  15. flames

    Effects of sour, wet gas corrosion in Carbon Steel Pipelines

    I agree with PVRV that you need to verify the indications with digs. The company you are working for should have guidelines for determining when an indication is a potential candidate to verify. If you are suspecting external than the procedure of excavation should include methods of...
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