3D Model — Orbit & Inspect
Scenario — Double Reeved Chain Configuration
The Task
Chain slings in a double-reeved configuration with a real load. Demonstrates how reeving increases the effective WLL without using larger, heavier chain.
Chain Grade
Check the grade marking stamped on every link. Grade 80 (marked “8” or “80”) and Grade 100 are the only grades permitted for overhead lifting.
Sling Angles
The included angle between sling legs affects the load on each leg. Wider angles = higher leg loads. Never exceed 120°.
Master Link
The master link at the top must be rated for the total load. Check it is not cracked, deformed, or worn. All chain legs must hang freely from it.
Hook Orientation
Hooks must face outward from the load and sit in the bowl of the master link or shackle. Safety latches must be functional and engaged.
Double Reeving Explained
Each leg of chain passes around the load and back up to the master link. This doubles the number of chain parts supporting the load on that leg.
Effective WLL Formula
The reeved factor combines the doubled-back geometry and the included angle between the two chain parts. 2.0 only applies when both parts hang parallel; capacity drops as the legs spread.
Reeved factors per AS 3775 (source: wwwroot/knowledge-base/verified-safety-data.json#slingAngleFactors):
| Included angle | Reeved factor |
|---|---|
| 0° (parallel) | 2.00 |
| 60° | 1.73 |
| 90° | 1.41 |
| 120° (maximum permitted) | 1.00 |
Calculation Example
Worked Example — 10mm Grade 80 Chain
Given:
10 mm Grade 80 chain
Single leg WLL = 3,200 kg
Double reeved (parallel legs, 0°):
WLL = 3,200 × 2.0
WLL = 6,400 kg per reeved leg
At 60° included angle the same configuration is rated to 3,200 × 1.73 = 5,536 kg.
| Chain Size | Grade | Single Leg WLL | Doubled WLL (parallel, ×2.0) |
|---|---|---|---|
| 7 mm | G80 | 1,500 kg | 3,000 kg |
| 8 mm | G80 | 2,000 kg | 4,000 kg |
| 10 mm | G80 | 3,200 kg | 6,400 kg |
| 13 mm | G80 | 5,300 kg | 10,600 kg |
| 16 mm | G80 | 8,000 kg | 16,000 kg |
Values above assume both parts of the reeved chain hang parallel. For any included angle > 0°, multiply the single-leg WLL by the reeved factor from the table above (1.73 at 60°, 1.41 at 90°, 1.00 at 120°).
When to Use Double Reeving
- When the load weight exceeds the single-leg WLL but is within the double-reeved capacity
- When you want to avoid using larger, heavier chain that may be harder to handle
- When the load geometry suits reeving — cylindrical or wrapped loads where chain can pass around and back
- When a choker hitch would derate too much (choker = 0.8 factor vs reeved = 2.0 factor at parallel legs, per AS 3775)
Advantages
- Increases effective WLL without upsizing chain
- Lighter gear to handle on site
- Better load control on rounded/cylindrical objects
- Reduces the number of sling sets needed in inventory
Critical Rules
Mandatory Requirements
- Both parts of the reeved chain MUST be the same grade — never mix Grade 80 and Grade 100 in the same reeved leg
- The load MUST be balanced — uneven loading on reeved legs causes one part to take more than its share
- Check that chain runs freely through the reeving point — a jammed chain means unequal load sharing
- The reeving point (shackle, hook, or load edge) must have a smooth radius — sharp edges damage chain links and concentrate stress
- Never knot chain to shorten it — use chain shortening clutches
- Inspect chain at the reeving point after each use — this is the highest wear zone
Rejection Criteria
- Any link stretched, bent, cracked, or gouged
- Wear exceeding 10% reduction in link diameter
- Missing or illegible grade markings
- Twisted or kinked chain that will not hang straight
- Heat discolouration (blue/purple tint indicates tempering loss)
Standards & References
- AS 3775.1 — Chain slings for lifting purposes: General requirements for the manufacture, testing, and use of chain slings
- NSW Dogging & Rigging Guide — Safe Work NSW guide covering chain sling selection, WLL tables, and reeving configurations
- AS 2321 — Short-link chain for lifting purposes — Grade T (80) and Grade V (100)
- AS 4991 — Lifting equipment: General requirements
- WHS Regulation 2017 (NSW) — Chapter 5, Part 5.1 — Plant and structures
Pre-Lift Checklist
- Confirm chain grade markings on every link are legible
- Verify WLL tag is attached and matches the chain
- Check master link, hooks, and safety latches
- Ensure chain runs freely through reeving points
- Calculate effective WLL using the AS 3775 sling-angle / reeved factor for the actual included angle
- Conduct a trial lift to verify load balance