WLL vs SWL
Definition
WLL and SWL are two terms for rated capacity that are no longer used as synonyms. The WLL (working load limit) is the manufacturer's rating, set by design and by the safety factor, and it is the term used in current European standards such as EN 1492 and EN 13414. The SWL (safe working load) is an older term. In current practice it can designate a limit set by a competent person for a particular configuration or condition of use (wear, angle, environment), which may be lower than the WLL. UK rigging guidance for loads over audiences, for example, gives a hoist with a WLL of 1000 kg an SWL of 500 kg.
In the field
The WLL is treated as the ceiling and any stated SWL as a possibly lower limit specific to the situation. Loading to the WLL on the assumption that the SWL is the same is unsafe, because the SWL may have been reduced for a reason that is not visible on the sling.
Related lessons
Sources
- PLASA / NRAG, Guidance: load suspension using electric chain hoists over stages and auditoria (janv. 2021), exemple : palan de WLL 1000 kg chargé à 500 kg comme SWL au-dessus du public · plasa.org
- EN 1492-1 (élingues textiles) : terminologie « working load limit » dans les normes européennes · puntofocal.gob.ar
- EN 13414-1 (élingues câble acier) : WLL et coefficient d'utilisation · knowledge.bsigroup.com