To ensure safety while climbing, it is important to retire aluminum carabiners when they show signs of wear and tear. Here are some guidelines to follow:
Check for gate action: If the gate rubs or sticks open, try cleaning and lubricating it. If this does not improve the gate action, retire the carabiner. The same applies to any gate locking mechanism.
Check for excessive wear: If the rope-bearing surfaces of the carabiner are significantly worn, retire it. Wearing off the anodization is normal after a few uses, but if you can feel that the surface is too rough, it's time to replace the carabiner.
Check for deformation: If the body or nose of the carabiner has deformed, or if the gate rivets have been bent, retire it.
Check for nicks or deep scratches: If the carabiner has nicks or deep gouges beyond normal light scratching, retire it. The areas near the nose hook or within an inch of the bending radii of the body are more susceptible to surface damage.
Check for exposure to extreme heat: If the carabiner has been exposed to extreme heat, such as in a fire, retire it and destroy it. The heat treatment the carabiner underwent during manufacturing may have been compromised.
Check for exposure to harsh chemicals or excessive corrosion: If the carabiner has been exposed to aggressive chemicals, such as battery acid or petroleum-based fuel, or if there is corrosion beyond the normal thin gray/white oxidation layer, retire it. If corrosion starts to affect the gate action, retire it immediately.
Remember, only you know what your gear has been through, and if there is any doubt about the safety of a carabiner, it's best to retire it rather than take a risk. Trust in your equipment is crucial for climbing safely and confidently.