TL;DR: Inspect in four stages: spine and body for cracks, grooves deeper than 1mm, or deformation; gate for a clean snap-shut with no lag; locking mechanism for full thread engagement; nose and keylock for burrs. Retire immediately if any defect shows up, or after a hard fall onto rock or concrete that changes how the gate behaves.
The 90-Second Field Check Every Climber Should Run Before Tying In
A pre-climb carabiner inspection isn’t complicated, but it has to be systematic. Petzl and DMM both publish formal PPE inspection protocols, and if you strip them down, you end up with a four-step field check that takes about a minute and a half.
Run this before you leave the ground:
- Look (20 seconds): Scan the frame, spine, and nose for cracks, corrosion, or sharp edges. Check the rope-bearing surfaces for grooves.
- Feel (20 seconds): Run a thumb along the inner basket and nose. You’re hunting for burrs or any sharp lip that could slice a loaded rope.
- Listen (20 seconds): Open the gate all the way and let it go. You want a sharp, immediate smack against the nose. A dull click means spring fatigue or grit in the hinge.
- Cycle (30 seconds): On locking carabiners, run the screw-gate or auto-lock through its full travel. It has to lock without you helping it.
Do this on everything on your harness, master-point locker down to the rope-end draws. Not just the “important” ones.
Reading the Spine and Frame: What Grooves, Pits, and Burrs Actually Mean
Most climbing carabiners are forged from 7075-T6 aluminum. Under EN 12275 and UIAA 121, a Type B biner has to hold at least 20 kN along the major axis. Wear chips away at that baseline.
Rope-wear grooves show up on the basket, where the rope runs. Petzl and DMM both draw a hard line at 1mm: once the groove hits that depth, the carabiner’s done. A 1mm groove changes the internal geometry of the aluminum and creates a sharp edge that can chew up a rope in a fall. On a 10mm frame, losing 1mm of material is 10% of the cross-section, and the strength hit is worse than linear.
Corrosion is the other big one. Surface oxidation on aluminum shows up as a dull white powder and is mostly cosmetic. Pitting corrosion, usually from saltwater, actually eats into the metal and creates stress risers. Galvanic corrosion happens when you store steel and aluminum biners jammed together in a damp pack (something you’d be surprised how often you see at coastal crags). If you’ve got deep pitting that doesn’t wipe off with a rough cloth, retire it.
Anodization loss, the colored coating wearing off, doesn’t weaken anything. The anodized layer is only a few micrometers thick, basically paint.
Gate Diagnostics: The Snap Test, Flex Test, and Lag Problem
The gate is the weakest point of any carabiner, full stop. If it doesn’t close completely, the biner’s strength falls from its major-axis rating (20-24 kN on most sport draws) to its open-gate rating, which is usually somewhere in the 7-9 kN range. 7 kN will fail in a bad lead fall.
Snap test first. Pull the gate fully open and let it go. It has to slam shut instantly. Any lag at all, even a fraction of a second, means the spring is tired or the hinge is contaminated. If a cleaning cycle doesn’t fix it, retire it.
Then the lateral flex test. Gate closed, push it sideways away from the spine. A healthy hinge barely moves. If the gate wobbles more than about 1mm sideways, either the hinge pin is worn or the frame itself is bent.
Wire-gates and solid gates fail differently. Solid gates have an internal coil spring, which traps dirt and moisture and corrodes from the inside out. Wire gates use the tension of the stainless wire itself, so there’s no internal spring to corrode, but the wire can take a permanent set if you crush it against a rock face.
Locking Mechanisms: Screw-Gates, Twist-Locks, and Triple-Action Failures
Different lockers, different checks.
For screw-gates, test the thread engagement. Spin the sleeve closed and it should run smooth across all threads. Cross-threading or grit lock-up means the threads are damaged. On a Spirit 3D, if that red warning band is still visible when the gate’s fully screwed shut, something’s obstructing the sleeve.
Auto-lockers (twist-lock and triple-action) depend on internal springs to pull the sleeve back home. Dirt infiltration is the number one killer. Open the gate and release it slowly. The sleeve has to snap all the way back to fully locked, on its own, no finger help.
The “frozen locker” problem is when aluminum oxide, chalk, and dirt pack into a paste inside the sleeve. DMM and Petzl both call for the same fix: wash in warm water (max 30°C / 86°F) with mild soap, dry completely, then put a silicone-based or graphite lubricant on the hinge and sleeve. Wipe off every bit of excess, because wet lube attracts more dirt than it displaces. If a full clean-and-lube cycle doesn’t bring the action back, it’s done.
The Nose, Keylock, and Where Catastrophic Failures Actually Start
So this is the section I’d pay the most attention to, because the nose-gate interface is where most of the bad stories come from.
Older biners use a hooked nose with a matching pin in the gate. Modern ones use a keylock: a smooth notch in the nose that receives the gate cleanly. Inspect the keylock notch for deformation. If the notch has been dented by whacking a bolt hanger, the gate can hang up on the lip instead of seating, and you’ll have a carabiner that looks closed but isn’t. That false-closed state is the thing that’ll get you.
Hooked-nose biners have their own problem: burrs. Every time a hooked nose smacks a steel hanger, the softer aluminum deforms a little, and eventually you get a sharp burr sticking out. A rope dragging across that burr in a fall can slice the sheath. I’ve pulled draws off climbers’ racks that had burrs you could feel from across the counter, and they had no idea.
Then there’s nose-hooking, which is the real nightmare. The nose of the biner snags on a bolt hanger or a wire nut and holds the gate open. According to accident narratives in Accidents in North American Climbing (ANAC), open-gate failures caused by nose-hooking or cross-loading are a frequently cited cause of carabiner breakage in the field, though the exact share versus other failure modes isn’t something I’ve seen cleanly broken out in the aggregate data. Visual inspection has to confirm the nose profile is still smooth enough to shed a hanger or a rope cleanly, with no hook or burr for anything to catch on.
This is also why keylock bolt-end biners on your draws are worth the extra money, especially for anyone cleaning sport routes. Obviously you’re not going to find a hooked nose on anything decent that’s been made in the last decade, but plenty of racks still have older stuff on them.
When “Dropped” Means “Retire”: Separating Lore from Manufacturer Policy
Climbing lore says any carabiner dropped on a hard surface has to be retired because of invisible micro-fractures. Metallurgical testing says otherwise.
Black Diamond’s QC Lab, back when Kolin Powick was running it, did extensive drop testing on aluminum biners, dropping them from 30 to 100 feet onto concrete and rock, then pulling them on the tensile rig. Carabiners that survived the drop without visible damage showed no significant strength loss. Micro-fractures in 7075-T6 from a gravity drop are, basically, a myth.
Manufacturer policies haven’t fully caught up to the lab data, though. Petzl’s PPE manual still tells you to retire after a “major fall or impact,” citing possible invisible internal deformation. I still retire draws after a serious cliff drop out of pure habit, even knowing the BD data, so I’m not going to pretend I follow my own logic here.
The practical consensus is visual and functional. If you drop a biner, check the gate action. Impacts bend frames slightly, invisibly to the eye but plenty to misalign the gate and nose. If the gate sticks, lags, or doesn’t seat perfectly after a drop, the frame’s bent, retire it. If it passes the 90-second check, it’s fine.
Retirement Timeline: Age, Use-Hours, and Environmental Triggers
Most carabiners don’t have an expiration date. Petzl and DMM both say metallic PPE has an indefinite lifespan. A biner sitting in a dry closet for 15 years is structurally the same biner that went in.
What actually drives retirement is use-hours and environment:
- Gym climbing: r/climbing threads report people retiring rope-end quickdraw biners after 1 to 2 years of heavy indoor use at 3-4 sessions a week. The chalk is the problem. It’s basically fine sandpaper, and it accelerates groove wear fast.
- Sport climbing: Bolt-end biners pick up deep scratches and gouges from steel hangers. Rope-end biners usually go 3 to 5 years on moderate weekend use.
- Coastal climbing: Salt accelerates pitting. Sea-cliff biners can be cooked in two years, usually with sticky gates as the first sign.
Track your own gear. If you buy a used rack and you don’t know where it’s been, you can’t rule out exposure to battery acid, pool chemicals, or industrial solvents, any of which can degrade aluminum silently. Unknown history, retire it. Not worth the gamble on a $12 part.
FAQ
Can I still climb with a dropped carabiner?
Yes, as long as it passes a careful visual and functional check. Black Diamond’s drop testing shows aluminum biners don’t develop strength-killing micro-fractures from falls. The real risk is a bent frame changing the gate action, or a fresh burr on the nose. Both of those show up on the 90-second inspection.
How deep can a rope groove be before I need to retire a carabiner?
1mm. Petzl and DMM both draw the line there, and the reason isn’t just the lost cross-section, it’s the sharp edge that forms as the groove deepens, which can chew up a loaded rope.
Do carabiners expire if I’ve never used them?
No. Metallic climbing gear has an indefinite shelf life per the major manufacturers. Nylon harnesses and Dyneema slings expire after about 10 years, but an unused aluminum biner in a dry drawer doesn’t degrade.
Is a scratched or scuffed carabiner weaker?
Surface scratches and lost anodization are cosmetic. Deep gouges, sharp burrs, or anything that actually changes the shape of the metal is a retirement call.
