Laboratory Testing & General Mineral Processing Engineering

Laboratory Testing & General Mineral Processing Engineering

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Fan shaft material that is corrosion resistant to dilute sulfuric acid (~15%) (1 reply)

2 years ago
Opie_Ute 2 years ago

We have a fan at my work, which has ~15% dilute sulfuric acid unintentionally pulled into the gas stream. The fan wheel and housing are constructed of 916L stainless steel. For many years the fan shaft had a 916L stainless steel sleeve on the portion of the shaft located inside the fan housing. A few years ago we installed a super austenitic stainless steel, UNS N08367, shaft on the fan. There were no problems with the shaft or Babbitt bearings until recently. Fast forwarding to present time, we have now experienced multiple failures of Babbitt bearings and damaged 4 of the UNS N08367 alloy shafts. We have now changed the shaft to a super duplex 255 stainless steel alloy (aka Ferralium 255), which has yet to be proven as a reliable alternative in this particular application.

Is there something about the UNS N08367 super austenitic stainless steel material that is a red flag in terms of not being a good fit for a ~1180 rpm fan shaft with Babbitt bearings (aka sleeve bearings)?

Are there similar red flags for super duplex 255 stainless steel alloy being used in the same application?

Todd H
2 years ago
Todd H 2 years ago

I have some experience with material of construction for acid autoclaves and we found that some ferralium alloys tend to suffer grain boundary corrosion in the presence of sulfuric fumes.  The vapor is the most corrosive, it appears to attack the crystal lattice.  We had reasonable success with duplex SS but in the most severe applications had to revert to titanium.



Todd Harvey - Global Resource Engineering

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