The shock-absorbing lanyard is the core component of a fall arrest system. Inside the heavy nylon webbing pouch at the end of the lanyard is a tightly folded, specially woven piece of webbing. When a worker falls, the violent force deploys this webbing, ripping the special stitches out one by one. This controlled tearing decelerates the worker slowly, keeping the fall arrest force on their body under 1,800 pounds, which is the limit a human spine can survive.
But this life-saving internal deployment pack is highly sensitive to its environment, and the way workers store their lanyards is completely destroying their ability to function. The most common, deadly mistake is leaving a lanyard in the back window of a truck cab or in an unventilated job box in the middle of summer.
The internal tear webbing is made of nylon. Nylon has a glass transition temperature; when it gets excessively hot, it softens and fuses together. When a lanyard sits baking in a 140-degree truck cab for weeks, the tightly packed internal webbing literally melts and bonds to itself on a microscopic level. The deployment stitches fuse into the surrounding fabric.
When a worker takes this heat-damaged lanyard out, it looks perfectly fine on the outside. But if they fall, the shock pack will not deploy. The fused webbing will refuse to rip, turning the shock-absorbing lanyard into a rigid, non-stretching tether. The full, unmitigated shock of the fall-often exceeding 5,000 pounds of force-will snap directly onto the worker's spine, causing severe compression fractures or instant death.
You must physically inspect the shock pack before every use. Squeeze the pouch. It should feel soft, pliable, and slightly lumpy, with distinct ridges you can feel through the fabric. If the shock pack feels like a solid, hard brick, the internal webbing has fused together and the lanyard is condemned. Furthermore, never sit on a lanyard, use it as a tow strap, or throw it in the bottom of a gang box where heavy tools can crush the internal stitches. A lanyard must be stored hung up in a cool, dry, dark place. If the fabric label on the shock pack is faded and brittle from the sun, the inside is just as ruined.
