stainless fasteners

[nnjunger]

There has been a concern raised of "gaulding" of stainless nuts when used with the stainless steel "studs" that we have in place. Is there a good reason to use carbon steel versus stainless in this application. Corrosion at the point of these fasteners is not an issue, the only reason that the studs is stainless is that the hoppers that they are attached too are stainless. Thanks in advance.

 

[MintJulep]

Is there a good reason to use carbon steel versus stainless in this application.

Don't know, you haven't told us anything about your application.

 

[NickE]

(1. Check out the grammar fourm.)

yes when using stainless to stainless fastener connections you must use an anti-sieze agent or you run the risk of the nut and stud Galling together.

There are several good anti-sieze compounds available, from relatively low temp ones to some that are designed to operate up to 1500F. Do a search on Metal and Metallurgy fourm.

I dont know about carbon versus stainless as far as you application cause like MintJulep I dont know your application.


Nick
I love materials science!

 

[stanweld]

Galling is a real concern when using austenitic stainless nuts and bolts, especially when they are the same grade. Assuming that your bolts/studs are subject to atmospheric corrosion, to prevent potentially rapid corrosion of the carbon steel nut, you may wish to consider the use of Grade 6 or 6F nuts made from martensitic stainless steel grades 410 and 416, respectively.

 

[nnjunger]

The studs will be holding on heaters, but will be covered in insulation. The corrosion is an issue on the material side of the hopper, hence the stainless steel construction. Our only concern was when a heater element breaks (as nothing runs forever) is being able to remove the old heater and attach another. The concern was the galling would prohibit unbolting and require us to cut the bolt, and then have to weld another stud on the hopper.

 

[arto]

Be sure to call for insulation per ASTM C795 "Standard Specification for Thermal Insulation for Use in Contact with Austenitic Stainless Steel" [low leachable chlorides]

Use Neverseez to prevent galling of stainless-stainless

http://www.bostik-us.com/products/index.asp?fa=categories&divisionId=6&categoryId=30

NeverSeez will work on heater installations - I usta use it on my muffler U-bolts - the nuts would come off easy, with clean threads underneath, even though everything else was rusty & crusty. The metal flakes stay behind, even if the grease part evaporates.

 

[EdStainless]

If you were to use carbon steel you must be careful welding them to the stainless hopper. I just finished inspecting a tank with 5,000 CS studs welded to 304 SS. It has been in service many years, but there are thoushands of studs with CSCC around them. The SS is highly sensitized in the welds and SCC loves that.
I would suggest that your studs match the hopper material. You can use a 4XX stainless nut and a Cu or Ni containing anti-seeze, you should be fine.

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Corrosion never sleeps, but it can be managed.

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