Rigging Tools & Calculators

Grade refers to the chain's minimum tensile strength per unit of cross-sectional area. Grade 70 is a transport/cargo control chain, not rated for overhead lifting. Grade 80 is an alloy chain approved for overhead lifting. Grade 100 is stronger than Grade 80, allowing a higher WLL in a lighter chain, and it's become the industry standard for lifting applications. Never use Grade 30 or Grade 43 (proof coil) for overhead lifting.

Start with four things: the weight of the load, the shape and surface of the load, the lifting environment (heat, chemicals, abrasion), and the required hitch type (vertical, choker, or basket). Wire rope slings handle abrasion and heat well. Synthetic slings are gentle on finished surfaces but vulnerable to cuts and chemicals. Chain slings are the most durable and heat-resistant. When in doubt, call us.

A design factor is the ratio of a sling's minimum breaking strength to its working load limit. ASME B30.9 requires a minimum design factor of 5:1 for most slings. Crane hoist lines typically use 3.5:1. Personnel hoisting requires 10:1. The design factor accounts for dynamic loads, wear, and the consequences of failure.

ASME B30.9 requires a visual inspection each shift before the sling is used, and a periodic inspection at intervals that must not exceed one year — yearly for normal service, monthly to quarterly for severe service. Inspections are performed by a designated person; a qualified person decides whether a deficiency is a hazard. A written record of the most recent periodic inspection is required for alloy chain and metal mesh slings; for the other sling types the standard requires documentation that the inspection was performed. We offer on-site inspections and can help you establish a compliant inspection program.

AWRF Accreditation is a voluntary program run by the Associated Wire Rope Fabricators. To earn it, a fabricator has to pass an independent third-party audit carried out by the Lifting Equipment Engineers Association (LEEA), the global standards body for the lifting industry. The audit covers products, fabrication processes, inspection practices, technical training, and documented quality management. Only a select group of companies hold it. Nelson Wire Rope passed its audit in April 2024.

For wire rope slings: 10 randomly distributed broken wires in one rope lay, or 5 broken wires in one strand. For chain slings: any crack, gouge, nick, or deformation; wear exceeding 10% of original dimensions; chain stretch. For synthetic slings: cuts, tears, broken stitching, chemical damage, heat damage, or a missing/illegible tag. When in doubt, remove it.

Screw pin shackles are quick to rig but can back out if the pin rotates during the lift, dropping the load. Bolt-type (safety) shackles have a bolt secured with a nut and cotter pin, far more secure for permanent connections, rotation-prone applications, and overhead lifts where backing out would be catastrophic.

Yes. In-house fabrication is one of our core capabilities. Wire rope slings, chain slings, synthetic slings, and custom hardware assemblies. Every sling we fabricate is proof-tested and certified before it leaves the shop. Call us with your specs.