Working Load Limit (WLL) is the maximum working load designed by the manufacturer. This load represents a force that is much less than that required to make the lifting equipment fail or yield. The WLL is calculated by dividing the breaking load limit (BLL) by a safety factor (SF). An example of this would be a chain that has a BL of 2,000 lb. WLL of 400 lb. if a safety factor of 5 (5:1, 5 to 1, or 1/5) is used.
WLL = BLL / SF
- For forged products Suncor uses a 5:1 safety factor (SF).
- For cast products Suncor uses a 4:1 safety factor (SF).
- For all other products, such as assemblies, Suncor uses a 4:1 safety factor (SF).