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  1. MaterialsDude

    Why do outside tubes of an exchanger suffer fretting the most

    Thanks guys for the answers. The shells side is a naptha/steam vapor mix, and the tube side is water. The purpose of the exchanger is to warm up water. There is an impingiment plate at the vapor entrance but it only covers a certain area. I've been told by one of the other engineers that the...
  2. MaterialsDude

    Why do outside tubes of an exchanger suffer fretting the most

    Well I am doing another anlysis on why some Type 304 stainless steel tubes failed by fretting in one of our exchangers. One of the things I noticed with the tubes located on the outrside perimeter of the tube bundle is that they tend to fail mainly by fretting. I know fretting in exhcnager...
  3. MaterialsDude

    Which is better for Heat Exchanger Tubes copper nickel 90/10 or 70/30?

    Thanks rmw. Well scaling and fouling are problems in the tubes due to the water chemistry of the water flowing through them. The scaling issue can be handled mainly through regular cleaning. Fouling is a result of bacteria presence in the water.
  4. MaterialsDude

    Which is better for Heat Exchanger Tubes copper nickel 90/10 or 70/30?

    EdStainless, It is funny that you mentioned that because I was doing research on the Sea Cure and it really does look like a good material. The only drawback that I read was that it isn't so good with fouling resistance due to no copper in its composition. Well we did have velocities as high...
  5. MaterialsDude

    Which is better for Heat Exchanger Tubes copper nickel 90/10 or 70/30?

    I checked out that website for HEI but couldn't find any such info. Isn't it http://www.heatexchange.org/
  6. MaterialsDude

    Which is better for Heat Exchanger Tubes copper nickel 90/10 or 70/30?

    Well we have determined that we may not go for the Copper nickel alloys due to their lower thermal conductivity relative to the admiralty brass. Anyone have any recommendations for a better material? Basically we need tubes that can withstand velocities of about 12 ft/s, resist corrosion from...
  7. MaterialsDude

    Which is better for Heat Exchanger Tubes copper nickel 90/10 or 70/30?

    Any idea where I could get some good info like design velocities etc for both these copper nickel alloys. The problem I am having is that a lot of websites provide info on these alloys in sea water applications......probably cuz they have historically been used in such applications.
  8. MaterialsDude

    Is anyone else bitter about work?

    so true man!
  9. MaterialsDude

    Is anyone else bitter about work?

    Very true IRstuff. My dad's a doctor and some of the stuff he does like operating in people's bums makes me happy I'm not him although he makes (or made as he is semi retired) some insane money. Thwere is stress in everything and often times that leads one to become bitter. Heck it wasn't that...
  10. MaterialsDude

    Is anyone else bitter about work?

    As someone mentioned, I think it is a "grass is always greener on the other side" case. It applies to all aspects of life too, even where you live. I was unemployed for a long time before finally working again, and now I sometimes find myself remincing about my unemployed time (because of all...
  11. MaterialsDude

    Tube failure on new bundle

    Mike, Good points, U know what's interesting is that I ws looking at the tube plugging pattern of all 6 heat exchangers we have, and noticed that the outside tubes are more often than not the ones that get plugged first or even the most. That was the trend for at least 4 of the 6 exchangers. I...
  12. MaterialsDude

    Tube failure on new bundle

    Hey guys, Thank you all for your replies. I talked with the boss this morning and she said that she did ask if we could pull out the tubes but that others in the company don't want to for whatever reason. The latest info I got was that the PSV valve popped after the condensate was contaminated...
  13. MaterialsDude

    Tube failure on new bundle

    Metengr, that's what I was trying to tell my boss because I believe that we have to take it out and send it for analysis but she told me that we won't do that. Obviously it makes my job a lot tougher especially considering that I am not that experienced with failure analysis.
  14. MaterialsDude

    Tube failure on new bundle

    So I am trying to figure out why 2 tubes failed (via leaking) on a new tube bundle that was recently installed in the exchanger. Right now I suspect 3 possible root causes: 1) Pressure surge: Shortly before the leaks were discovered in a hydrotest, a PSV valve popped. 2)Velocity: These are...
  15. MaterialsDude

    Which is better for Heat Exchanger Tubes copper nickel 90/10 or 70/30?

    I'm researching both Copper Nickel 90/10 and 70/30 as possible tube materials for heat exchangers as an alternative to Admiralty brass which the company has been usuing and is looking to replace. Basically I want to know if anyone has had experience with these materials and if they are ideal for...
  16. MaterialsDude

    What type of corrosion am I dealing with?

    rconner, It def doesn't make sense to me but the process engineer never got back to me when I questioned it so I just put down whatever info he gave me. I'm not even sure a biofilm could stay on a surface with that speed lol!
  17. MaterialsDude

    What type of corrosion am I dealing with?

    Ok guys, I got some updates. The pipe is API 5L Gr.B carbon steel pipe. Pipe specification is CAJ. Typical operating pressure is 910 kPag and typical operating temperature is 2C. The typical flow velocity is 7000 cubic meters/second. The failure actually occured at the 12:00 position and the...
  18. MaterialsDude

    What type of corrosion am I dealing with?

    Thanks guys! Right now we have sent the samples to a testing company after we put together a scope of work to be done. Also, the process engineer was in a meeting when I tried to go to his office and ask questions regarding the operating conditions in the pipe. You guys provided some really...
  19. MaterialsDude

    What type of corrosion am I dealing with?

    metengr, It's kinda almost exactly in the middle side of of the horizontal pipe. Here's a pic of the pipe where the sample came from. I'm assuing that the combination of the MIC and under deposit (probably from a biofilm) caused pitting corrosion which caused the hole in the pipe. Does this...
  20. MaterialsDude

    What type of corrosion am I dealing with?

    Thanks for the replies so far guys.I don't know how long the pipe has been in service for. I'll have to ask them next week when I go to the plant. This is the only portion of the pipe that failed and removed. I tried to post more pics but I guess you can onlu post one at a time. Here's another...

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