In lifting operations such as the use of jib cranes, hoists or slings, plus applications such as rigging, load restraint, material handling, fall protection, construction and demolition—it is essential that safe lifting limits are respected.
The use of terminology is how manufacturers of lifting equipment can guide users on how to use any equipment or lifting equipment accessories safely.
Two commonly used terms are working load limit (WLL) and safe working load (SWL).
However, while both SWL and WLL may be used interchangeably, there are some key differences to note.
Here is an overview to explain the differences between a safe working load and a working load limit from the lifting experts here at Metreel.
WLL – Working Load Limit
Working load limit definition: The maximum load that lifting equipment such as chains, hooks, ropes or slings are designed to raise, lower or suspend.
When calculating the WLL, the manufacturer will rate the equipment in relation to its breaking load based on the factor of safety.
The factor of safety is only valid when new, and doesn’t accommodate damage which may occur to items which may reduce the amount of mass that can be safely lifted. Aspects which can reduce the factor of safety include abrasion, age of equipment, chemicals, cuts, knots and solar degradation.
The equipment will undergo a series of tests to determine the WLL based on the equipment’s breaking strength. This refers to the point at which the equipment would fail or break. Exceeding the WLL increases the risk of equipment failure, which is why the limit needs to be respected.
If the usage of the equipment differs from the standard methods, then the responsible person in charge of the operation will need to calculate the new WLL.
SWL – Safe Working Load
Safe working load definition: Safe working load is the maximum load that the equipment can safely lift, lower, move or suspend safely under normal operation conditions.
The key aspect to know about SWL is that it is a term which has since been replaced by WLL. Specifically, SWL was replaced for everything below the hook. Rated capacity became the new rating system for cranes, hoists and winches.
While it’s still common to hear SWL being referenced, it doesn’t hold any standing from a safety standpoint in modern times. The reason is that legally, it is very difficult for manufacturers to state that a load may be safe to lift.
Furthermore, there was often a lot of ambiguity over SWL which created risk management challenges. WLL was brought in to create clarity so that everyone from the engineers of the lifting equipment to the end users can best understand what constitutes a safe amount to lift, including based on the different types of conditions which may occur.
Metreel – Discover Effective Lifting Solutions For Your Business
Now you know the differences between SWL and WLL, are you keen to discover our vast range of material handling solutions?
Based in Derbyshire, Metreel supplies industrial lifting solutions to businesses across the UK and beyond.
Check out our products on our website to learn more, or give us a call on 0115 932 7010 to speak to our sales team.