The rated capacity of a multiple leg sling is directly affected by the angle of the sling leg with the horizontal. As this angle decreases, the stress on each leg increases with the same load. If the sling angle is known, the capacity can be readily determined by multiplying the sling’s vertical capacity by the appropriate load angle factor from the table at below:
| Sling Angle | Load Angle Factor |
|---|---|
| 0 (Vertical) | 1,000 |
| 75 degrees | .966 |
| 60 degrees | .866 |
| 45 degrees | .707 |
| 30 degrees | .500 |
| 15 degrees | .259 |
Example: A multiple leg sling with a rated capacity of 2000 lb. will have a reduced capacity of 1000 lb. (2000 x .500) when sling legs are at an angle of 60 degrees with vertical.
Wire Rope Sling Inspection
Conditions such as the following should be sufficient reason for consideration of sling replacement:
- For strand laid and single part slings, six (6) randomly distributed broken wires in one rope lay, or three (3) broken wires in one strand in one rope lay.
- For cable laid and braided slings of less than 8 parts, twenty (20)randomly distributed broken wires in one lay or braid, or one(1) broken strand per sling.
- For braided slings of 8 parts or more, forty (40) randomly distributed broken wires in one braid, or two (2) broken strands per slings.
- Severe localized abrasion or scraping.
- Kinking, crushing, bird caging or any other damage resulting in distortion of the wire rope structure.
- Evidence of heat damage or if a wire rope sling having a fiber core is exposed to temperatures in excess of 200 degrees F. or if a wire rope sling having a steel core is used at temperatures above 400 degrees F or below minus 60 degrees F.
- End attachments that are cracked, deformed, or worn.
- Hooks that have been opened more than 15% of the normal throat opening measured at the narrowest point or twisted more than 10 degrees from the plane of the unbent hook.
- Corrosion of the rope or end attachments.
- Unlaying or opening up of a tucked splice.