First foray into stainless steel

I'm wondering if the washers need to be passivized? Another thought is electrolysis, chemically induced, or maybe electrical?
 
Aukai said:
I'm wondering if the washers need to be passivized? Another thought is electrolysis, chemically induced, or maybe electrical
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What does passivizing do?
 
Citric acid is used in the process for canning food, so it is safe, and easy to find. Any time you work SS it will have a tendency to rust.. Hot water 140*~ and the amount of citric acid to volume, let soak, rinse, and done.
 
If you contaminate stainless by contact with steel tooling, eg hss, file, deburrer then you will need to passivate it with pickling paste which is nasty stuff. It'll change a shiny finish to a matt look finish also. Make sure you follow the instructions to the letter.
Teflon would have been fine as a spacer as long as you're not changing any critical impeller clearances.
 
devils4ever said:
Now you tell me. :)
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As noted earlier, Teflon will creep (cold flow) under pressure. So your once tight fasteners will get looser and could fall off. This can be bad. Stainless is better. Says the guy who used Teflon washers under fasteners once. Won't do it again.
 
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There doesn't have to be a high level of torque on the impeller nut, only enough for it to hold position. There most probably is a spring behind the impeller which preloads the mechanical seal so the only torque required is to match the spring tension. In my experience the pump will or should be serviced yearly so you can monitor any deterioration in the Teflon washer and change material if required.
 
Impeller pumps do have some axial thrust from the magnetic field when energized, but it's a fairly small force. Stainless is probably a more permanent fix. Small impeller pumps (double digit wattage) I've worked on have had teflon or UHMW thrust washers. I had a 140w titanium impeller pump in service once that ran on ceramic, which held up to the resonance of cavitation very well. I'm just kicking the tires here, the Jersey devil has already solved the dilemma optimally.
 
No, there is no spring inside the housing. It's just the washer, followed by the impeller and the SS shield. The whole thing get clamped to the main housing with a ring shaped SS clamp that has a V-shaped groove. I think it's called a tri-clamp. The pic below shows the clamp in the bottom left corner. The washer isn't shown separately, so must be on the shaft already.

But, pontiac is probably correct in that the magnetic field axially pulls on the impeller.

I disassemble the whole thing after every brewing session to clean it. With the amount of time and money spent brewing, it's not worth not keeping everything as clean and sanitized as possible.

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I machine quite a bit of 316 and your process sounds fine. As mentioned center drilling should not be an issue and with parting the same comment as above, just keep it cutting don’t pause. Once you commit just go. Only going .083 in for parting so I think you will do fine. Good luck.
 
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