Get a handle on WLL, SWL and MBL
If you use Lifting Equipment, you should also know the terms WLL, SWL and MBL - these are important terms for understanding the equipment you use.
WLL vs. SWL – is there a difference?
WLL stands for 'Working Load Limit' while SWL stands for 'Safe Work Load'. In short, the maximum lifting capacity of the equipment. Both WLL and SWL are used in everyday speech and the two things cover exactly the same thing, i.e. the equipment's maximum lifting capacity. However, SWL is an older term which started to be phased out around 20 years ago, but there are still industries, e.g. the offshore industry, where the term is still used. But why did they start phasing out SWL? This is because there have been certain legal consequences when the word 'Safe' is used in connection with lifting - therefore the term has been phased out by manufacturers etc. and now only WLL (Working Load Limit) is used.
What affects the WLL of the equipment
When combining several Lifting Equipment parts in one lift, the lowest WLL specification is always applicable.
The indicated WLL is also only valid for a straight lift with one party. If the lift is not straight and a round loop is sensed around a load, a different load factor applies and thus a different WLL. When lifting with several parties, different load factors are used - you can find these for e.g. Round Slings, Webbing Slings and Chains on our Load Tables. When lifting with several parties, other factors also come into play, such as e.g. angle of inclination, and therefore you cannot be content with just looking at the load factor.
MBL
MBL stands for 'Minimum Breaking Load', i.e. minimum breaking strength. MBL therefore indicates the number of kg the equipment must be able to withstand before a break in the equipment occurs
Safety factor (SF) – an important concept
The Safety Factor indicates the factor between WLL and MBL. WLL = MBL/SF. For lifting gear, the Safety Factor for the various types is between 2:1 and up to 9:1. The Safety Factor is determined based on the applicable standards for the individual equipment types. Round Slings, for example, has a safety factor of 7:1, i.e. that a Round Sling with a WLL of 1 tonne has an MBL of as much as 7 tonnes.
In this video you can see what it looks like when this round sling is pulled to break in our draw bench:
Test Loading
Some types of lifting equipment also require a test load when we carry out the statutory inspection every 12 months. The degree of the test load with which the individual types of equipment must be tested is determined based on the same EN standards as WILL and MBL, and can be different both based on the type and the WLL of the equipment. Our service technicians have the necessary equipment to carry out these test loads to various degrees in the inspection process, just as it is written on the individual equipment's certificate if the equipment should be test loaded.
