What Is WLL in Rigging?
WLL is stamped on every shackle, sling and hook, but it is often confused with breaking strength. Mixing the two up is dangerous. This guide explains what WLL means in rigging and how to use it safely.
What Is WLL?
WLL stands for working load limit. It is the maximum load a piece of rigging equipment is rated to lift or pull in normal service. The WLL is the number you must never exceed during a lift.
WLL vs Breaking Strength
Breaking strength is the load at which the component actually fails. WLL is always much lower, because it includes a safety factor. A shackle with a 5 tonne breaking strength may carry a WLL of only 1 tonne, giving a 5:1 safety factor.
The Safety Factor
Rigging standards generally require a safety factor of 4:1 to 6:1. That margin covers shock loads, uneven loading and wear over time. Never use breaking strength as your working figure.
WLL on Common Rigging Gear
Shackles: WLL is stamped on the body and rises with pin diameter.
Slings: WLL depends on material, ply and the hitch used.
Hooks: WLL is stamped or marked and varies with size and grade.
Chain: WLL depends on grade (G80, G100) and link size.
How to Use WLL When Choosing Gear
Calculate the maximum load, including shock loads.
Choose gear whose WLL meets or exceeds that load.
Confirm the WLL marking and certificate before the lift.
Never size gear exactly to the load; always leave margin.
FAQ
What is the difference between WLL and SWL?
They mean the same thing: the safe working load. WLL (working load limit) is the current term; SWL (safe working load) is the older equivalent.
How do I find the WLL of a shackle?
The WLL is stamped on the shackle body. If it is not readable, the shackle must be taken out of service.
Rig With the Right Ratings
SolidLink marks every shackle, hook and chain assembly with its WLL and provides material certificates. Browse our shackles or contact us for a quote.
