Galling with stainless steel fasteners

[Gryphon Rider]

I just thought I would share a little bit of knowledge that I have just now gained from experience.  I am using an M10 stainless steel bolt with a stainless nyloc nut, and found that the second time fastening them, I couldn’t get the nut as snug as I had the first time. I now find it impossible to take apart, so I will be using a dremel with a cutting disk to remove the nut.  After reading up on this problem, I have learned that to prevent this I should have used a moly or graphite anti-seize.  One more use for the moly paste I use on the Valk’s rear wheel splines.

[Ken aka Oil Burner]

Funny; building racecars 25-30 years ago, we used to use Maalox as a lubricant/anti-galling agent when using stainless fasteners. It worked!

[WintrSol]

Funny; building racecars 25-30 years ago, we used to use Maalox as a lubricant/anti-galling agent when using stainless fasteners. It worked!

Makes sense; Maalox stands for magnesium-aluminimum oxide, and should make for finer particles than moly or graphite. Great tip, if you can still find it at the drug store.

[ridingron]

We used to use the silver colored anti-seize for the stainless hardware (mostly 1/2" X 13) when I was working. When they galled and couldn't be loosened, we revered the impact gun and would wring the nut off. That was easier to do than fight with it and generally twist the bolt in two anyway. 

[h13man]

The past 5 yrs. or so I noticed this on just about the every Ny Lock nuts both in SS and regular steel in my inventory and most came from Menards over years. I actually used a regular nut to back up the SS lock nut due to this exact chit. I'd say that good nylon isn't being used or it appears to me by sight, soft UHMW  plastic as nylon has a more opaque/cream color. At best the new stuff can seal moisture out but holding power, not w/o a split locker.

[Pluggy]

We define galling as micro friction welds between two fastners.  In the worst case, those fastners will bond together.  

Gryphon, where did you buy the fastners?  Home store hardware may not be the same quality as we use in industry.  

At the factory, we recognize the potential for stainless galling, but rarely have it.  Quality fasteners, controlled assembly speed and torque are in the process.  We typically don't reuse the "Nyloc" nuts.  We typically don't use "assembly lube", either.  All fastners are clean and new.

Home Depot stainless fastners, used, assembled quickly with power tools, have a potential for galling.  But, that's the hardware available to most of us.  When we use this stuff, we must take our time and assemble it carefully.

[Gryphon Rider]

Gryphon, where did you buy the fastners?  Home store hardware may not be the same quality as we use in industry.

I got them at a local industrial supply store. They are marked A2, so they are 304 stainless. The other mark is THE, which I assume is the manufacturer. I fastened/tightened them by hand, no power tools.

[Pluggy]

304 is the common alloy for stainless fasteners.  Are you unusually muscular?  Looking at the Fastenal chart, we can tighten M10 to 30 ft. lb.  If the hardware is clean and new, that galling shouldn't have happened. Anti-seize compound can work, but under high vibration can cause fasteners to loosen, so we typically won't use it for military equipment.

Hope you have everything fixed up.

[WintrSol]

Instead of NyLok, reserved for smaller than #10, and rarely used for flight hardware, we used the kind that I can't recall the term for, but with thin cuts across a tapered end, and the end set with a die to close the gaps. A bugger, but possible, to get back off, and never used twice.

[Gryphon Rider]

304 is the common alloy for stainless fasteners.  Are you unusually muscular?  Looking at the Fastenal chart, we can tighten M10 to 30 ft. lb.  If the hardware is clean and new, that galling shouldn't have happened. Anti-seize compound can work, but under high vibration can cause fasteners to loosen, so we typically won't use it for military equipment.

Hope you have everything fixed up.

While I AM the go-to guy at my house to open jars, I didn’t over-tighten this bolt. Using moly paste seems to work fine, as I was able to test fit, remove, and reinstall without issues.

[crow]

Nylok nuts, like cotter pins, shouldn't be reused.  I  only use a Swagelok product named Silver Goop.  THE best

Antisiez there is for stainless.   A one oz tube is around 180.00 bucks. Use sparingly, like brill cream, a little

dab will do ya.