Rigging and load assessment
To assess the load correctly before the lift begins
Introduction
Rigging is the link between the crane and the load. A lift cannot be safer than the rigging that bears it. Therefore, every crane lift begins with an assessment of what is to be lifted, how heavy it is, where the center of gravity lies, and what equipment is suited to the task.
Assessment of weight and center of gravity
Before the lift, the weight of the load must be known. It may be marked on the item, appear on delivery notes or drawings, or be calculated from the material's density and volume. An estimate is not enough when you are close to the capacity of the gear or the crane. The centre of gravity decides how the load hangs: if the lifting points are not placed around the centre of gravity, the load will tip or turn when it is lifted clear of the ground.
The rule is in the executive order on the use of technical equipment: You must not lift when there is doubt about whether the lift is safe — e.g. because of the weight of the load or the slinging. The weight of the load including the lifting accessories must be established when it matters for safety (BEK no. 428 of 05/04/2022 § 44).
Selection of lifting gear
Rigging equipment includes, among other things, chains, wire slings, fiber slings (round slings and straps) as well as shackles, hooks, and lifting eyes. Each piece of equipment has a marked working load (WLL – Working Load Limit) which must never be exceeded. The equipment is chosen based on the load's weight, shape, suspension angle, and surface – sharp edges require edge protection so the sling is not cut.
- 01Chains: robust, withstand high temperature and sharp edges better than fibre
- 02Wire straps: strong and flexible, but can get breaks on the individual wires
- 03Fiber slings: lightweight and gentle on the surface, but vulnerable to sharp edges and chemicals
The angle decides how much the gear may carry
When a load hangs in two or more legs and the legs are at an angle, the force in each leg increases the larger the angle from vertical. That is why the gear may carry less the more the slings are spread. The table is from the German statutory accident insurance's guide for slingers (DGUV Information 209-013) and applies to a two-leg sling:
| Angle from vertical | Capacity per leg | Two-leg sling in total (× one leg's WLL) |
|---|---|---|
| 0° | 100 % | 2 × 1,0 = 2,0 |
| Up to 45° | 70 % | 2 × 0,7 = 1,4 |
| 45°-60° | 50 % | 2 × 0,5 = 1,0 |
| Above 60° | Prohibited | — |
Inspection of equipment
Rigging equipment must be inspected before use. Equipment with visible damage is discarded: broken wires in cable, deformed links or stretched chains, cuts, heat damage, or heavy wear in fiber slings, and shackles with worn or deformed bolts. Damaged equipment is immediately taken out of service.
Lifting accessories must be checked every time they are used. They must also be inspected according to the manufacturer's instructions — and at least every 12 months if the manufacturer does not state otherwise (BEK 428/2022 § 25; BFA Bygge & Anlæg). Many use a colour code that shows when the gear was last inspected. The colour code is industry practice, not law:
| Year of last inspection | Colour |
|---|---|
| 2024 | Green |
| 2025 | Yellow |
| 2026 | Blue |
| 2027 | Red |
| 2028 | Green — then the sequence starts again |
| Discarded gear | White |
Discarded gear must be kept separate from the other gear so that it is not used again by mistake. Read more in the article on discarding lifting gear.
Communication during the lift
Rigging and crane operation are often two people. Clear signals are arranged – hand signals or radio – and only one person directs at a time. The stop signal must be given and understood by everyone. No one stays under a suspended load.
The slinger and the crane operator have both the right and the duty to refuse a lift if they have doubts about it (BFA Bygge & Anlæg). And measures must be taken so that people do not stay under suspended loads (BEK 428/2022 § 45).