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...
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.
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...
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...
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...
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...
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...
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?
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...
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...
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.
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...
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...
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...
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.
