[TowerTalk] Stainless Steel Galling (Larry McDavid)

[Larry McDavid]

K1TTT wrote:
> Works fine for me, though grade 8 nuts would be overkill for most ss bolts.
> 
Indeed, yes! Here is what I replied but forgot to send to the reflector:

Unless the U-bolt is fully supported, I doubt you can approach full 
tensile strength of the U-bolt itself; I don't know the incidence of 
galling in that case. If you have experienced galling, using even Grade 
5 nuts should stop it. But, realize the Grade 5 nut is *much* stronger 
than the stainless steel U-bolt; the bolt will strip long before the nut.

Grade 5 and Grade 8 nuts and bolts are plated for corrosion resistance 
but they will not be perfect, particularly if consistently wet or in the 
presence of any salt spray. I use them here in Los Angeles without much 
corrosion, but we have very little rain or moisture and no salt spray 
where I live in Anaheim.

My opinion (un-tested!) is that a Grade 5 nut on stainless would not gall.

Mind you, the stainless steel U-bolts I've seen have poor threads--the 
major and pitch diameters are undersize, making the nut fit a bit loose. 
So, be careful torquing the nut or you may strip that stainless U thread.

If extreme tension in the U itself is not essential, you could put two 
Grade 5 nuts on each side and use the outer nut as a jam nut. If you are 
as anal as am I, you could put an internal tooth lock washer or even a 
split lock washer (available in Grade 5) between the two nuts.

Larry W6FUB

...
>> At 17:36 2010-06-25, Larry McDavid wrote:
>>> If you are screwing a stainless steel
>>> bolt into brass or aluminum, don't expect galling. . . .
>>
>>
>> Larry, thank you for the interesting comments on galling.
>>
>> A common situation is a stainless U-bolt on an antenna,
>> with stainless nuts supplied.
>>
>> What would you think about tossing the stainless nuts and
>> using Grade 8 plated steel nuts? I would replace the nuts
>> each time the U-bolt needed adjustment.
>>
>> Mark, K5AM
>>
>>
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-- 
Best wishes,

Larry McDavid W6FUB
Anaheim, CA  (20 miles southeast of Los Angeles, near Disneyland)