>From http://www.estainlesssteel.com/gallingofstainless.html...
"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."
I always use an anti-seize compound on stainless hardware.
73,
Mike
WM4B
-----Original Message-----
From: towertalk-bounces@contesting.com
[mailto:towertalk-bounces@contesting.com] On Behalf Of Dana Roode
Sent: Sunday, January 03, 2010 8:32 PM
To: towertalk@contesting.com
Cc: Dana Roode
Subject: [TowerTalk] Seized mast clamp bolts Hy-gain 10 meter yagi
Howdy - I assembled a new LJ-105CA 5 element Hy-Gain yagi for 10
meters this past week. I put it up temporarily on a mast to work on
it. For some reason 3 of the 4 5" stainless steel bolts on the mast
clamp seized to the nuts after I raised the yagi on the mast a few
feet and tried to re-tighten them.
Anyone know why this happens? The bolts are new, although they have
been in the box with the rest of the yagi parts for several years.
The beam is also unbalanced at the mount point and that may have
torqued the bolts as I was moving the beam around (BTW, is it worth
trying to balance this yagi before it goes up?).
When I replace the mast bolts, should I go with stainless steel as
Hy-gain does or some other material?
I also have the same antenna for 15 meters that is on top of a 45'
military tower. I noticed those bolts are seized as well when I
checked to see if they were still tight.
Dana
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