Lifting and Rigging Basics and Terminology
Basic Terminology
Below you will find Key Terms in the Lifting and Rigging industries. These are important to understand in order to hold a conversation with customers and help them choose the right product for their job. NOTE: We never tell a person how to lift or rig an item. We only advise the rated capacities of our products.
Working Load Limit – Also known as the Safe Working Load, WLL, SWL or Working Load, it is the maximum load which should ever be applied to the product under any condition. The WLL is based on a load being uniformly applied in a straight-line pull.
Proof Load – The load a product can withstand during the manufacturer’s quality control testing for the purpose of detecting defects and deformation in the material. The Proof Load for chain is applied at twice the value of the Working Load Limit.
Minimum Breaking Strength (MBS) – Do NOT use MBS for design or rating purposes. Always use the Working Load Limit instead. Minimum Breaking Strength is an average figure at which samples have been found to break under laboratory conditions, in straight-line pulls with constantly increasing loads. These conditions are rarely duplicated in actual use. The MBS applies ONLY to new, unused chain.
Click the Play button in the center of the video below to watch a real break test at the Advantage Testing Facility.
Lift Angle – A term applied to Chain Slings, the lift angle affects the WLL. When a Lift Angle is higher, the rating of the sling also increases. When the Lift Angle decreases, the working Load Limit also decreases.
Click on the Information Icons below (i) to learn how to identify the Lift Angle.
Identifying Lift Angles
In this industry, the lift angle is identified where the legs of the triangle meets the base.
45° Angle Lift
In this example you will see the double leg wire rope sling legs meet the load attachment point at a 45° angle.
Sling Tag – An end user has the right to know the capacity of the sling they are using. A sling tag will show the critical information that the end user will need to select the proper rigging for the job. This information on a chain sling will show Manufacturer Name, Manufacture Date, Certification Number (which normally can correspond to a paper/digital Certificate of Conformance), Chain Diameter, Number of Legs, Working Load Limits (at different lift angles if multi legged), Reach Measurement and Sling Configuration.
Reach – A term applied to Chain Slings, it is the measurement from bearing point to bearing point. This measurement must be accurate. During a chain sling inspection, reach discrepancies can indicate overloading, stretch or equipment modification.
Design Factor – An industry term denoting a particular products’ theoretical reserve capacity. It is a Ratio which divides the MBS/WLL.
Grade 30 Proof Coil: 4:1
Grade 43 High Test: 3:1
Grade 70 Transport: 4:1
Grade 80 Alloy: 4:1
Grade 100 Alloy: 4:1
Fatigue/Cycle Test – A test administered to gauge the durability of products. In the chain and hardware industry, this applies only to Grade 80 and Grade 100 products. This test is administered at 1.5 times the working load and has a minimum cycle count of 20,000 to be considered a passing test.
Shock Load – Loads which exceed the static load caused by rapidly changing movements such as jerking, impacting, or swinging of load. Working Load Limits Do Not Apply in these conditions.