> Buried in the fine print is the sentence: "Carabiners are stamped with a
strength rating that
> describes their failure load -- the force under which the carabiner will
> when it is properly loaded."
Good to know. Thanks for pointing that out.
I did some further research on this. Carabiners of recent manufacture are
stamped with two numbers. The first is the "closed gate" failure rating,
usually 18-25 KN (4,050-5625 lbs.) The second number is "open gate" failure
rating, usually 6-8 KN (1,350-1,800 lbs.) Obviously, the gate does a lot
more than keep your rope from slipping out of the carabiner. It's an
integral part of the strength rating. The pin in the gate must be securely
engaged with the hook in the body of the carabiner in order for the full
strength rating to be realized. When the gate is open, the strength rating
is severely derated.
> If you do any tower work and don't own a half dozen of these you don't
> know what you are missing.
Half a dozen? I have at least 20 of 'em and never seem to have enough!
In my opinion, self-locking carabiners with a pin release are the safest for
man-load tasks because it's virtually impossible for the gate to be opened
unintentionally. I've never seen a screw-sleeve lock get accidentally
unscrewed, but I guess it could happen. The problem is that the operator may
forget to screw down the sleeeve. Another problem is that if the sleeve
isn't unscrewed far enough, the gate won't close, greatly reducing the load
capacity. Can't happen with the self-locking variety.
That said, I don't use self-locking carabiners for all my climbing
applications because I feel that in some situations the self-lock presents a
greater safety hazard than the screw-sleeve. I often find it very difficult
to release the self-lock, especially when wearing gloves. It's even more
difficult in cold weather and/or when my fingers are tired after doing a lot
of work on the tower (activating the safety latches on my fall arrest and
positioning lanyard hooks over and over tends to tire out the fingers and
hands, not to mention gripping tower rungs and tools tightly.) This problem
occurs both when removing the carabiner and attaching it -- i.e., you can't
just snap the carbiner in place. You have to operate the lock, pull back the
gate, slip it on, then release the lock. This takes coordination and hand
What I like to do is use self-locking carabiners for applications where the
carabiner stays engaged most, if not all, of the time. For example, my
fall-arrest lanyard is connected to the D-ring on the back of my harness
with a 25 KN self-locking carabiner. It's never removed from the harness,
even between climbs. I feel confident that the carabiner behind my back
(that I can't see) isn't going to accidentally open. Similarly, I use a 25
KN self-locking carabiner to anchor a 6" climbing strap to my front D-ring.
There's a screw-sleeve carabiner at the other end. I can quickly snap the
screw-sleeve carabiner to a tower rung when I need a quick rest while
climbing. I use it instead of threading my belt positioning lanyard through
the tower -- much quicker, easier and safer. The self-locking carabiner on
my chest D-ring almost never gets removed. I use the screw-sleeve type at
the other end because it's much easier to operate. The sleeve is retracted
while I'm climbing, so I can quickly snap the carabiner on a rung. If I'm
going to be there a while, I engage the lock. All the while, of course, my
fall arrest Y-lanyard is also clipped to the tower.
I also carry an assortment of carabiners on my harness belt. They're great
for hanging tools and equipment. You never know when you're going to need
one. I tend to use the non-locking type for simple stuff like hanging tools,
and the sleeve-lock type for tasks where the gate could potentially open
Finally, I use carabiners for hauling loads up the tower and for tramming
antennas. Most of the time I prefer to use the screw-sleeve variety. I want
the gate locked because in hauling situations it's common for the load to
contact the tower. A non-locking carabiner could open when that happens. I
don't like using the self-locking type for hauling and tramming because it's
harder to open and keep open when removing the load from the carabiner (or
removing the carabiner from the load.)
73, Dick WC1M
TowerTalk mailing list