topic changed to "terminating old Phillystran"
You received correct advice that old design Phillystran WILL NOT work
with big grip style terminations. The cover does not adhere to the
kevlar fibers and the fibers lay parallel to the cover, it will slip
right off.
I am using old 24k# rated old Phillystran from a BCB station with the
proper terminations - Spelter sockets with epoxy potting of the kevlar
fibers. See my NCJ article Nov/Dec 2014. One of my terminations was
tested to failure on a 100k# force test stand. At 24k# the fibers near
the socket failed, not the potting.
I did a fair amount of research about using cable clamps. While a
marginal technique, I think it may work to achieve a termination
strength of about 50% of the rated breaking strength of the Phillystran
using 4 cable clips. The clips need to be tightened and retightened
about 4 more times over a period of a few days, basically until the
clamps cut thru the cover and bare directly on the Kevlar fiber. Best
done when the temps are warm so the plastic creep is accelerated. Use
about 70% of the rated cable clip torque for a same size steel cable of
the fiber diameter.
Phillystran boom guys often use cable clips since guy grips aren't made
that small. The same advice applies for the smallest current
Phillystran, re-tighten over a few days at the proper torque until the
cover fully compresses.
btw, I wouldn't use the old stuff again, too much work. A surprise was
that the cover can move enough a couple of years after installation that
kevlar is exposed an inch or two on 150' long guy ends. Since Kevlar is
UV sensitive the fix was to Scotch 33 around the Spelter socket and
Phillystran. Contrary to CW Kevlar is pretty much inert to other
environmental challenges. It works fine as anchor rodes for offshore
oil platforms.
Testing reports available direct.
Grant KZ1W
On 10/8/2018 7:11 AM, Speer, Douglas via TowerTalk wrote:
I bought some new old stock 0.300" Phillystran. I was told by the seller that
this older Phillystran is not intended to be used with the preformed Big Grip
Dead-Ends. Instead I was told to use traditional thimbles and clamps to form my
ends. Does this sound right? Would I torque up the clamps just to the point that
the Philly is staring to compress? My only previous experience terminating
Phillystran is with the dead ends. If it matters, I will be using this Phillystran
to guy an insulated tower for use as a vertical. No wind load to speak of other
than the tower itself.
Doug, W5WTX
Amarillo, TX
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