Lifting and Rigging Equipment: select the right eye bolt
There’s a lot of hardware to consider when researching lifting and rigging equipment. Links, hooks, swivels—today we’re talking eye bolts. Eye bolts are used to attach a securing eye to a structure, so ropes or slings can be pulled through.
Keep reading to discover how to select and use the right type of bolt, their dimensions and Working Load Limits.
Eye bolts are marked with thread size, not with their rated capacities. Make sure you select the correct eye bolt based on type and capacity for the lift you are conducting.
- Use plain or regular eye bolts (non-shoulder) or ring bolts for vertical loading only. Angle loading on non-shoulder bolts will bend or break them.
- Use shoulder eye bolts for vertical or angle loading. Be aware that lifting eye bolts at an angle reduces the safe load.
- Follow the manufacturer’s recommended method for angle loading.
Lifting and Rigging Equipment: using eye bolts safely
- Orient the eye bolt in line with the slings. If the load is applied sideways, the eye bolt may bend.
- Pack washers between the shoulder and the load surface to ensure that the eye bolt firmly contacts the surface. Ensure that the nut is properly torqued.
- Engage at least 90% of threads in a receiving hole when using shims or washers.
- Attach only one sling leg to each eye bolt.
- Inspect and clean the eye bolt threads and the hole.
- Screw the eye bolt on all the way down and properly seat.
- Ensure the tapped hole for a screw eye bolt (body bolts) has a minimum depth of 1 1/2 times the bolt diameter.
- Install the shoulder at right angles to the axis of the hole. The shoulder should be in full contact with the surface of the object being lifted.
- Use a spreader bar with regular (non-shoulder) eye bolts to keep the lift angle at 90° to the horizontal.
- Use eye bolts at a horizontal angle greater than 45°. Sling strength at 45° is 71% of vertical sling capacity. Eye bolt strength at 45° horizontal angle drops down to 30% of vertical lifting capacity.
- Use a swivel hoist ring for angled lifts. The swivel hoist ring will adjust to any sling angle by rotating around the bolt and the hoisting eye pivots 180°.
Lifting and Rigging Equipment: eye bolt techniques to avoid
- Do not run a sling through a pair of eye bolts: this reduces the effective angle of lift and puts more strain on the rigging.
- Do not force the slings through eye bolts. This force may alter the load and the angle of loading.
- Do not use eye bolts that have been ground, machined or stamped.
- Do not use bars, grips or wrenches to tighten eye bolts.
- Do not paint an eye bolt. The paint could cover up flaws.
- Do not force hooks or other fittings into the eye; they must fit freely.
- Do not shock load eye bolts.
- Do not use a single eye bolt to lift a load that is free to rotate.
- Do not use eye bolts that have worn threads or other flaws.
- Do not insert the point of a hook in an eye bolt. Use a shackle.
- Do not use non-shouldered bolts to lift horizontally—non-shouldered bolts should only be used to lift vertically.
Lifting and Rigging Equipment: eye bolt dimensions
Machinery Eye Bolt
Screw Eye Bolt
Regular Eye Bolt—Forged
- The Ultimate Load* is 5 times the WLL**. Maximum proof-load*** is 2 times the WLL.
Shoulder Eye Bolt—Forged
- Ultimate Load is 5 times the WLL. Maximum proof-load is 2 times the WLL.
* Ultimate Load: The load at which the item being tested fails or no longer supports the load.
** Working Load Limit: The maximum combined static and dynamic load in pounds or tonnes should be applied to the product in service, even when the product is new, and when the product is uniformly applied in direct tension to the product.
*** Maximum Proof-Load: The maximum tensile force that can be applied to a bolt without deformation. This is usually between 85-95% of the yield strength.
Need more definitions? Find common securing, rigging and lifting definitions on our ‘Quality and Safety‘ page.
Fact sheet via CCOHS: https://www.ccohs.ca/oshanswers/safety_haz/materials_handling/eye_bolts.html