wire rope and zinc-poured sockets... 2

[DaveVikingPE]

Oh, the projects I get myself into...

In my research on how zinc-poured sockets "work" pertaining to wire rope, I've found API 9B "Recommended Practice on Application Care, and use of Wire Rope for Oil Field Service" and the very interesting American Rigger's Supply, Inc. catalog. I also have my old Handbook of Ocean and Underwater Engineering. At home I have a neat book on cable structures - but I'm not at home right now...

Anyway, the API almost gets me what I want: just how strong is a zinc-poured socket? The American Rigger's Supply catalog, however, has load ratings. For example, a zinc (or resin - ?) poured socket used with a wire rope diameter of 2.5 inches have a rated capacity of 52 tons = 104 kips. The length of the Improved Plow Steel (IPS) socket that's in contact with the poured zinc is 9.75 inches (open or closed socket, the length is the same).

How am I to interpret this? I am assuming that the zinc poured is of ASTM B6 grade 1 (from the API 9B...). I'd like to say that there's a direct relationship between the length of the socket in contact with the zinc and the socket's length. For example, my 2-1/2 inch diameter wire rope zinc-poured socket has a strength per inch of length of 104 kips/9.75 inches = 10.67 kips/inch. If I could justify that, my day would end in triumph.

Any assistance is most appriciated! Thanks to all in advance!

refs:

http://americanriggers.thomasnet.co...-resin-poured/poured-sockets/ps-062?&seo=110.

http://wwwrcamnl.wr.usgs.gov/sws/cableways/descr.htm

http://www.dsiamerica.com/products/Multistrand_Couplers.html

- eh, not really what I was looking for, but it helped a little.

 

[btrueblood]

Erg. I see the data on the american riggers site, Dave, but my Machinery's Handbook lists wire rope breaking strengths of well over 200 tons for 2.5 inch rope diameters, so a breaking strength of 52 tons seems awful low (especially when Machinery's Handbook and the Am Riggers website both suggest joint efficiencies of 100% for poured sockets).

 

[DaveVikingPE]

Well, then, I've got to get myself a copy of the Machinery's Handbook!

If there's 1005 effciency, I'm happy! Thanks!

 

[hokie66]

Rated capacity and breaking strength are not the same thing.

 

[DaveVikingPE]

OK... then what kind of info is out there on the bond or adhesive strength between zinc and another metal?

 

[DaveVikingPE]

...other than this:

http://iadr.confex.com/iadr/2002SanDiego/techprogram/abstract_10683.htm.

 

[btrueblood]

See page D-10 in

http://www.usbr.gov/ssle/safety/RSHS/AppD.pdf

Also this

http://www.usace.army.mil/publications/eng-manuals/em1110-2-3200/c-3.pdf

Every manual lists the "spelted" or poured socket as the fitting used to measure breaking strength of wire rope, thus these fittings must reliably be able to attain 100% of the rope's strength.

Publishing a "rated load" for wire rope and fittings is somewhat criminal. Dave, I'd suggest you buy a fitting from somebody else. Breaking strength is a no-bull**** rating. Users of wire rope and fittings should apply the appropriate safety factors for their particular situation (static vs. running loads, human life/safety, etc.).

 

[DaveVikingPE]

Excellent! Thanks again!

 

[kelowna]

I am with btrueblood here, every socket I have seen or worked with has always been rated at 100% of the rope/strand strength. They are designed that way!
Usually, for suspenders on bridges you also do a destruction test with a sample socketed at both ends. The test is considered as passed when the assembly achieves the 100% capacity of the rope.