Rigging Carabiner Choice

[cap n chris]

Small delta alloy screwgates.

 

[Loki]

Spanner

No need to be like that.

 

[EvilStu]

"Don't screw up, screw down" so that the gates screw-lock will try to "move" towards the closed/locked position with any movement or vibration.

Well I was always shown to rig that way with screwgates despite more recently being told
it makes no difference.
So after 35+years of doing SRT, on Saturday I watched a screwgate carabiner unscrew itself upwards while a caver was descending
a 20m pitch using a petzl simple on a sqeaky dry rope, in just 10metres of abbing it had fully unscrewed, I did it up, backed it off 1/2 a turn and it did the same again while the caver abseiled below the deviation. Wish I'd had a camera to film it! Then I did it up proper tight before going down myself.

 

[JAshley73]

Well I was always shown to rig that way with screwgates despite more recently being told
it makes no difference.
So after 35+years of doing SRT, on Saturday I watched a screwgate carabiner unscrew itself upwards while a caver was descending
a 20m pitch using a petzl simple on a sqeaky dry rope, in just 10metres of abbing it had fully unscrewed, I did it up, backed it off 1/2 a turn and it did the same again while the caver abseiled below the deviation. Wish I'd had a camera to film it! Then I did it up proper tight before going down myself.

Yup... Vibratory tumblers work this way...

So I fall back on my love of auto-lockers, or twin-gates.

 

[mikem]

You can still only unclip it when you're above it

 

[cap n chris]

Well I was always shown to rig that way with screwgates despite more recently being told
it makes no difference.
So after 35+years of doing SRT, on Saturday I watched a screwgate carabiner unscrew itself upwards while a caver was descending
a 20m pitch using a petzl simple on a sqeaky dry rope, in just 10metres of abbing it had fully unscrewed, I did it up, backed it off 1/2 a turn and it did the same again while the caver abseiled below the deviation. Wish I'd had a camera to film it! Then I did it up proper tight before going down myself.

More common than you might imagine. It's amazing to watch, isn't it?

 

[Inglesport]

I don't love the idea of aluminum carabiners in stainless hangers. The pressure will deform, and thus scratch thru the anodizing on the carabiner. In practicality, this is of little concern, but as a machinist with a mild interest in metallurgy, something I think about.

Also as a machinist, and someone who makes threads & screws, I don't love the idea of screw-locks. To function, threads need clearance, and threads with clearance move. Yes I know the addage of "Don't screw up, screw down" so that the gates screw-lock will try to "move" towards the closed/locked position with any movement or vibration.

So, I prefer the ever-reliable springs of Auto-lockers whenever possible. And if using in hangers, steel.

-For use in bolt-hangers - Some "cheap" Metolius steel D auto-lockers from a local store.
-For Munter/Italian hitches if need be - same as ^^^
-For use in webbing, an auto-locker or Grivel twin-gate.
-If it must be a screw-lock - then make it a Petzl so that you get the fantastic anodized red/dead bands showing that the gate isn't fully screwed closed.

Also, am I the only guy that really prefers ovals to D-frame krabs? I like the idea that they're a little more versatile in regards to having a big wide basket for webbing, not worrying about them cross-loading, and can easily flip them to satisfy whatever gate-direction you want...

Even if it doesn't help with gate vibration, one advantage of always using your carabiners the same way round is that it keeps any damage from the hanger at one end so it doesn't affect the rope.

It's most common with aluminium carabiners used on stainless steel plate hangars (rather than rounded, resin fixed ones) but the softer aluminium can develop a small burr which can then abraid the rope. If you always use them in the same orientation the rope end stays nice and smooth.