Date: Wed, 07 May 2014 16:41:00 -0400
From: Tom Nicholson <Gunsrus1942@Comcast.net>
To: Mike Ryan <mryan001@tampabay.rr.com>, towertalk@contesting.com
Subject: Re: [TowerTalk] ROHN TOWER BOLTS
NO FLAMES HERE!
Here is what I have for choices:
Not the average Home Depot / Lowes "Stuff"
A286 Super Alloy?With approximately 26% nickel and 15% chrome, this
iron-based super alloy brings you the strength of alloy steel with
corrosion resistance similar to 18-8 stainless steel. It meets ASTM A453
Grade 660 and is not magnetic. Screws have a minimum Rockwell hardness
of C31 and minimum tensile strength of 140,000 psi.
17-4 PH Stainless Steel Alloy?Combines the high strength of alloy steel
with the corrosion resistance of stainless steel. It meets ASTM F593
Grade 630 and is magnetic. Screws have a minimum Rockwell hardness of
C31 and minimum tensile strength of 140,000 psi.
Alloy 20 Stainless Steel?Also known as Carpenter 20 screws. With
excellent resistance to sulfuric acid, these screws have a minimum
tensile strength of 80,000 psi.
I also have a choice of 18-8 or 316 SS Nylon lock nuts.
Tom W1ALZ
## 18-8 is now history...and replaced by the 3XX series of hardware.
The 3XX is still 18-8.... its just a numbering change.
## Compare G-5 bolts and mating nuts with your proposed
SS alloys you listed above. (SAE-G5 is the same as astm A-325 bolts.)
## I had one helluva time when using SS bolts with the mating SS nylocks a
few
years ago. I had several cases where the SS nylock nut would seize up
badly...
just before it was even finger tight. Never had a problem when using plane
jane
SS nuts. Dunno what it was with those SS nylocks. I would recommend
running
a tap through the SS nylocks.....and running a die down the SS bolts. All
you need
is one tint ding in the threads..and the damned things will seize up......and
that’s
with never seize already applied.
## On a similar note... a buddy of mine has a K0XG rotating 55 G tower. His
top 3
sections are the beefed up sections...with the extra diagonals in them. They
weigh
a bit more than regular 55G sections....and look like a continuous X.... plus
the usual
horizontals. He has 25 feet of this beefed up sections above the very top
ring.
## A few months ago, one of the bolts fell right out...and landed next to the
tower base.
Upon inspection, the nut from the 2nd bolt on the same leg has vanished !
This install
is new as just a few years ago. The vibration at times appears to shake the
tower pretty
good with the myriad of yagis installed on it. Dunno why Rohn didn’t use
nylocks everywhere.
UST uses nylocks on everything. Apparently the new style Rohn nuts are one
time use only,
and will not vibrate loose. Think about it for a minute......putting a nut
on a bolt that is through a
tubular leg is asking for trouble imo. The nuts is not bearing down on a flat
surface but a curved
surface. You can only crank so much torque on those bolts too.
## Hopefully the new style nuts fair better. Nylocks or the use of loctite
blue..thread locker
would also work. Loctite also makes loctite purple..which is slightly
weaker than the blue stuff.
Dont use locite red..or you will never get the nuts off. Freaks me out when
you see bolts and nuts
falling off at the 180 foot level of a 190 foot tower.
## whats really needed is mating THICK washers..that have a curve on one
side..to mate to the curvature
of the tower leg...and flat on the other side..so the nut can bear down on a
flat surface.
Jim VE7RF
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|