[TowerTalk] Terminating old Phillystran with Spelter sockets

[Grant Saviers]

I recently concluded testing of wire rope clamps (clips) on "old" 
parallel Phillystran (PS).  The old PS does not work with the current PS 
guy grip type of termination. These tests showed that clamps as a 
termination system has risks that are not acceptable to me.

Since the factory no longer supplies the socket type termination made 
for old PS, I undertook tension tests using off the shelf Crosby Spelter 
sockets made for steel wire rope.  These sockets develop full breaking 
strength of the cable and the steel strands are held with epoxy in the 
tapered socket.  The PS guy being tested is the 5/8" od 27,000# breaking 
strength and will be preloaded to a maximum of 600# and has a 
requirement of 6700# breaking strength for the tower in permitting.

Using West Marine series 105 epoxy, I was able to sustain 12,000# 
tension in the test sample with acceptable creep over a period of 5 
days.  This result is far superior to what I could obtain with cable 
clamps and a dubious clamp tightening procedure.  With a Spelter socket 
there is no damage to the PS sheath and the termination completely 
encapsulates the Kevlar fiber from UV and weather.

There may be improvements to the system with alternative epoxies, which 
I may consider for further testing.  However, at this point I have a 
termination system proven to my satisfaction for the tower guys I need 
using the 1800' of old PS I have.

I will gladly send a pdf copy of my new Spelter socket or prior cable 
clamp test reports to topbanders or towertalkians that request it off-line.

73,

Grant KZ1W