Ask a maintenance crew how they keep bolts tight and you'll hear the classics: lockwire, thread-locking compound, nylon insert nuts, lock washers. All of these fight loosening. Only some of them prevent a drop — and that distinction matters enormously when the hardware is overhead.
Two different jobs
Loosening prevention keeps the joint tight. Drop prevention keeps the fastener attached if the joint fails anyway. Vibration, thermal cycling, improper torque, and fatigue can defeat any locking method eventually. The question is what happens next: does the bolt sit loose in its hole, or does it fall 40 feet onto someone?
Lockwire (safety wiring)
Aviation-style safety wiring is proven and positive — the wire physically prevents rotation and retains the head if it backs out. The trade-offs are labor and skill: drilled-head bolts, twist-pitch technique, and re-wiring at every service interval. On a crane with hundreds of fasteners maintained by rotating crews, wire quality drifts, and a poorly twisted wire gives false confidence.
Thread lockers and lock nuts
Chemical thread lockers and prevailing-torque nuts resist rotation well within their temperature and torque limits, but they offer zero retention once the fastener is out. They also complicate inspection — you can't see whether a thread locker has degraded.
Tethered bolts
A tethered bolt pairs the fastener with an engineered lanyard anchored to the structure. Retention is built into the fastener rather than added in the field, so there is nothing to re-apply at each service interval. It doesn't replace your locking method — it backstops it. If the bolt backs fully out, it hangs, visible and recoverable. Installation uses standard tools and torque procedures, and inspection is a visual check.
The practical answer: layer them
Keep your locking method for joint integrity and add tethered retention where a drop would land on people or critical equipment. Rank locations by height and traffic underneath; retrofit the worst first.
Safety Wire Bolts manufactures tethered fasteners made to order — thread size, grade, finish, and tether rating built to your spec. Request a quote.