Safe Working Load Limits- Terminology

SWL, NWL, MBS — all of the acronyms can get very confusing. Don’t fret – we’re here to clear things up when it comes to safe working load limits and the terms associated with it.

Safe Working Load (SWL) sometimes stated as the Normal Working Load (NWL) is the mass or force that a piece of lifting equipment, lifting device or accessory can safely utilize to lift, suspend, or lower a mass without fear of breaking. Usually marked on the equipment by the manufacturer and is often 1/5 of the Minimum Breaking Strength (MBS) although other fractions may be used such as 1/4, 1/6 and 1/10.[1][2][3]

Other Terms Used in the Industry

Other synonyms include Working Load Limit (WLL), which 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, also known as the Minimum Breaking Load (MBL). SWL or WLL are calculated by dividing MBL by a safety factor (SF). An example of this would be a chain that has a MBL of 2000 lbf (8.89 kN) would have a SWL or WLL of 400 lbf (1.78 kN) if a safety factor of 5 (5:1, 5 to 1, or 1/5) is used.
As such:WLL = MBL / SF

Safety First! We’re Here to help.

Here at Industrial Rope Supply, we are not only committed to providing you with a quality product, but also with all the information needed to insure safety comes first on every job. Have safety questions on a product purchased from us? Contact us today and we’ll be happy to talk you through and/or provide you with the safety materials needed.

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