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  1. TEV

    Galvanic Corrosion in mixed SS - Paper

    Ed - Thanks for the contact. I will give Jim a call. I found the paper I was looking for myself, with a search on Google's Scholar search site. Great site! The paper can be found at http://allvac.com/ludlum/Documents/86-228%20DMC.pdf. It does show enhanced galvanic corrosion of some more...
  2. TEV

    swagelok/parker

    In response to JLSeagull, Parker has been using a "special hardening process" on ALL of their ferrules for over 20 years, compared to Swagelok's approx 10 years. Parker's process is AT LEAST equivalent to theirs. And their single ferrule fitting does have some advantages.
  3. TEV

    Galvanic Corrosion in mixed SS - Paper

    I recall seeing a paper published some time ago describing sea water galvanic effects between some different austenitic and (I think) duplex stainlesses that showed a galvanic corrosion reversal between 316 and another SS. The author may have been Kearns. I cannot locate the paper. Can anyone...
  4. TEV

    Galling threads

    Yes, you will have galling. You need to prevent stainless-to-stainless contact to pevent it. This may be accomplished by using teflon pipe tape, plating the mating surfaces with a soft, deformable metal, and/or using a dry film lubricant such as molybdenum disulfide in a polymer. Critically...
  5. TEV

    anneal stainless steel

    Why do you need to anneal for machining? We actually prefer strain hardened stainless for machining, as we get less stringy chips, better surface finish, and reduced tearing (with form tools). For some of our machined products, we actually specify fairly strongly strain hardened barstock and...
  6. TEV

    Carburizing Stainless Steel

    A couple of other possibilities. I assume the shaft is made of cold drawn barstock. If it is austenitic stainless steel, the cold deformation could induce enough transformation to martensite to give the slight magnetic response noted. Also, some of the austenitic stainlesses on the market now...
  7. TEV

    Heat treatment Stainless Steel 316L

    We have had similar problems with barstock, and as I recall, it was also with ugine material. When we drilled a hole in one end of the bar, then unchucked, rechucked and drilled the other end, the first end became oval. We initially thought it was due to chucking pressures, but further...
  8. TEV

    High Presssure Fittings

    Grampi - Thanks! Any ideas on where to find these "semi-official historical guidelines", besides going to the wellhead suppliers you mentioned? Or are they proprietary to the suppliers?
  9. TEV

    High Presssure Fittings

    Where are high pressure (15ksi max) fittings in sizes 1/4, 3/8 and 1/2 inch used in petroleum recovery, refining and chemical processing, and what specifications are customarily applied? ASME/ASTM? MR0175? MR0130? What applications are there outside of the petrochem industry? What specs...
  10. TEV

    High Pressure Tube Fitting

    We have a new high pressure stainless steel tube fitting for use with hard drawn or thick walled SS tubing in sizes 1/4, 3/8 and 1/2 inch. The design provides an easily made leak-tight connection at pressures up to 15 ksi with a safety factor of four. We don't have a very good handle on the...
  11. TEV

    AL6XN tubing

    Parker Hannifin's Instrumentation Products Division makes 6Mo tube fittings, but I don't think they have them in sanitary designs. They got into this for North Sea drilling platforms about 15 years ago.
  12. TEV

    Turning 304 / 316 magnetic

    304 and 316 will become slightly magnetic when deformed due to a martensite transformation. The martensite is magnetic. The leaner the alloys are in austenite stabilizing alloying elements (Nickel, Carbon, Nitrogen) the more susceptable it is to this transformation. We have even observed...
  13. TEV

    Purging 304

    I am involved in the specifications for high purity gas supply systems for semiconductor plants. These systems are 316L stainless tubing welded with automatic welding systems. They are required to be purged with essentially no welding discoloration. The alloy specs are optimized for welding...
  14. TEV

    Stainless steel for hot water boilers

    I agree with EdStainless. What is the hardness of the formed stainless? The higher the hardness, the more susceptable it will be to chloride SCC. Flux splatter or other surface contamination could also be a factor. it is very important to clean the surface and passivate it, if possible...
  15. TEV

    316/316L versus 316Ti

    As McGuire states, 316Ti is common in Europe. The European version also generally has a minimum of 2.5% Mo, compared to the American versions of 316, which are typically about 2.1% Mo. This will also improve pitting resistance.
  16. TEV

    Hardening of 316 St/St

    It sounds like you are thinking of the Kolsterizing process, which does give you a very hard case about 25 microns deep on austenitic stainlesses, but the black color is not necessarily a result of Kolsterizing. Another possibility is burnished-in Molybdenum Disulfide, which will result in a...
  17. TEV

    Galling of SS hardware

    Most manufacturers of stainless tube fittings (Swagelok, HamLet, etc.) use silver plating on the ID threads of the nuts to avoid galling. Parker Hannifin uses Molybdenum Disulfide on their CPI fittings, which is particularly effective both as a lubricant and preventing galling. It is available...
  18. TEV

    316L SS WELD CRACKING

    P, S, and Si are the elements to which weld cracking is generally attributed in austenitic stainlesses. These elements are always present in SS, but control of these elements within a narrow range is preferable. But, as andyenergy has stated, the detrimental effects of these elements is greatly...
  19. TEV

    corrosion by CO2

    The gas companies - Air Products, Air Liquide, etc. - have very comprehensive info available on their web sites about compatibility of various materials with gases. Take a look.
  20. TEV

    304 SS for Marine Applications

    Electropolishing will only improve the corrosion resistance of austenitic stainlesses (304, 316, etc.) marginally, as it can eliminate surface features such as heavily cold worked surface metal, surface inclusions and impurities, and crevices due to folded metal or other effects. If the surface...

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