Roger,
I think you should read the Phillystran docs a bit more carefully, see
my prior post for links. Philly is still terminated with a Spelter like
socket. Big Grips are available on the lower strength guys (except 1200).
From the specs: "The Corona Sockets are aluminum, resin filled, potted
end terminations and are always factory installed." Available at the
1200 size and larger, although not for every break strength cable.
If you read my NCJ article, it is about older Philly that must be
terminated with epoxy filled sockets, Big Grips do not work on any
size. However, according to my discussion with Phillystran engineering,
they do not sell the sockets any more except to the military and perhaps
special contractors. Also, the factory epoxy is not available in the
USA even though it is in catalogs. With about 1500' of 25k old Philly
on hand, I was in search of a full strength and reliable termination
technique and proved it with extensive long term tension testing and
testing to failure.
They changed to Big Grips on the smaller sizes when they changed the
core design from parallel strand Kevlar fibers to that similar to
conventional 3 strand stranded rope, although there are more strands of
Kevlar in current Philly.
Anecdotes, "my boom hasn't bent yet" are interesting, but show me the
tension test data for saddle clamp terminations that were installed a
few months ago.
I still have my tension tester, able to generate 20k lbs tension and
someday might get around to some more tests.
Grant KZ1W
On 10/22/2015 0:26 AM, Roger (K8RI) on TT wrote:
This should not be a factor where the Phillystran is used as a truss
at a fraction of its strength. As guy lines the standard "Big Grip is
recommended. They haven't used Spelter sockets and epoxy for some
years even on the larger 6,000# cable.
For a truss 3 saddle clamps are used with the saddle on the live side
(never saddle a dead horse) so creep has never been a problem when
used on a truss. The Big Grips (Recommended by Phillystran and sold
by vendors) grip entirely on the jacket, but it's over about 18" or
more. If you wrote a recent article recommending Spelter sockets, it
is not what the manufacturer recommends, hence they have not been the
proper method of termination for a number of years. I don't know when
they changed, but it was Big Grips in 2002, or 13 years ago when I
installed my 45G using Phillystran's recommendations. I didn't find
any sellers of Phillystran even offering Spelter sockets.
Follow the "Prime Directive"
73
Roger (K8RI)
On 10/21/2015 11:35 PM, Grant Saviers wrote:
I strongly advise against saddle clamps. The problem is creep of the
plastic jacket causes the clamp force to decay with time. Until the
clamp completely cuts through the jacket the clamp force decays. At
room temperature it took about 3 weeks and at least 4 tightenings to
get the saddle to cut through the jacket. I used a torque wrench to
set the tightening force and measured the residual torque at a late
time each cycle. I built a tension tester and verified saddle
terminations will slip well below the breaking strength of the
Philly. Even after 121 days and 4 tightening cycles the saddle clamp
torque values indicated continuing creep and reduced termination
strength. I was unable to achieve more than 30% of the break
strength of the Philly. (25000# Philly and 7000# load for slippage).
Later I tested the proper terminations for this Philly (Spelter
sockets with epoxy) on a commercial 100,000# tension test stand and
the guy failed at 28000# tension and not the termination. See NCJ
Nov-Dec 2014 for my article.
I've seen bent booms as a result of using saddle clamps. I also
found them loose on my steppIR 4L after a year on the 1200 size so
will never use it again.
Phillystran says use grips on all 2100 and larger. Follow the
directions!
Grant KZ1W
On 10/21/2015 13:06 PM, Mike Reublin NF4L wrote:
Mostly what compresses is the jacket. No strength is lost. My
SteppIR uses Phillystran (as a bridle) with small saddle clamps. The
PS is very flat in the clamps.
73, Mike NF4L
On Oct 21, 2015, at 3:46 PM, GMuller885--- via TowerTalk
<towertalk@contesting.com> wrote:
All:
Thank all of you for the input. Based on all the input my
guys and
stays are of Phillystran 6mm dia 2100 lbs break strength. I am
using guy
line clamp kits, three to a connection. The only question left is
that if
the Guy cliompress the Phillystran how much strength is lost if any?
Gerald Muller K9GEM
GMuller885@aol.com
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