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13406 SE 32nd St, BELLEVUE WA, 98005 WWW.CONSUMER.STEPPIR.COM TEL: (425)-453-1910
From time to time, we get complaints from customers regarding galling of stainless steel fas-
teners.
Here is an excerpt from the Industrial Fastener Institute's Standards Book: Thread galling
seems to be the most prevalent with fasteners made of stainless steel, aluminum, titanium
and other alloys which self-generate an oxide surface film for corrosion protection. During
fastener tightening, as pressure builds between the contacting and sliding thread surfaces,
protective oxides are broken, possibly wiped off and interface metal high points shear or lock
together. This cumulative clogging-shearing-locking action causes increasing adhesion. In
the extreme, galling leads to seizing - the actual freezing together of the threads. If tightening
is continued, the fastener can be twisted off or its threads ripped out.
During minor galling, the fastener can still be removed, but in severe cases of galling, a
strong bond between the bolt and nut can prevent removal of fasteners. Here are two ways to
minimize this effect: Decreasing installation RPM speed will cause less friction and decrease
heat generation. Lubrication used prior to assembly can dramatically reduce or eliminate gall-
ing. Recommended lubricants should contain higher amounts of molybdenum disulfide, such
as graphite which is very commonly used as a solid lubricant or special anti-galling lubricants
sold by chemical companies.
We provide an anti-seize compound stick called “Thread Magic” with all of our antennas and
strongly encourage you to use it to reduce the aggravation of galling. Nylock nuts are no
exception—apply the anti-seize on fasteners that use Nylock nuts as well. The Thread Magic
stick is fantastic and is good for all metal fastener use—and, you can get plenty of anti-seize
on the fastener without getting it on your hands!
Turn-of-nut tightening of nuts to bolts is recommended where torque values are not named,
with metal to metal connections. Turn the wrench/socket until it is flush with the material it will
seat against and snug-tightened, and then turn approximately 2/3 of a rotation past that point.
When in doubt use common sense to ensure the fastener is not too loose, or not too tight—
both positions can cause issues. On all connections, check the tightness 30 minutes or more
later to ensure no creeping has taken effect.
Contrary to popular belief, galling of stainless steel is not a symptom of a "cheap" fastener - it
is prevalent in all types of stainless steel, aluminum, and titanium fasteners. You can be as-
sured that the stainless steel fasteners we provide with our products are manufactured of
very high quality.
Save yourself a lot of grief and always use a thread lubricant when working with stain-
less steel fasteners.
STAINLESS STEEL FASTENER INFORMATION
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