Every polyester webbing or round sling carries one number on its label: the working load limit for a straight lift. Everything else — choking it, wrapping it into a basket, pairing it with a second sling — is that number multiplied by a mode factor. The chart below does the multiplication for every capacity we list, so the figure for the hitch you are about to rig can be read straight off.
/01The capacity chart, every hitch.
Working load limit in tonnes for each hitch, for every capacity in our round sling range. The same factors apply to flat webbing slings of the same rating.
| Sling WLL | Colour | Straight | Choked | Basket, parallel | Basket, 0–45° | Basket, 45–60° |
|---|---|---|---|---|---|---|
| 1 t | Violet | 1 | 0.8 | 2 | 1.4 | 1 |
| 2 t | Green | 2 | 1.6 | 4 | 2.8 | 2 |
| 3 t | Yellow | 3 | 2.4 | 6 | 4.2 | 3 |
| 4 t | Grey | 4 | 3.2 | 8 | 5.6 | 4 |
| 5 t | Red | 5 | 4 | 10 | 7 | 5 |
| 6 t | Brown | 6 | 4.8 | 12 | 8.4 | 6 |
| 8 t | Blue | 8 | 6.4 | 16 | 11.2 | 8 |
| 10 t | Orange | 10 | 8 | 20 | 14 | 10 |
| 12 t | Orange | 12 | 9.6 | 24 | 16.8 | 12 |
| 15 t | Orange | 15 | 12 | 30 | 21 | 15 |
| 20 t | Orange | 20 | 16 | 40 | 28 | 20 |
| 25 t | Orange | 25 | 20 | 50 | 35 | 25 |
| 30 t | Orange | 30 | 24 | 60 | 42 | 30 |
| 36 t | Orange | 36 | 28.8 | 72 | 50.4 | 36 |
| 40 t | Orange | 40 | 32 | 80 | 56 | 40 |
| 50 t | Orange | 50 | 40 | 100 | 70 | 50 |
| 75 t | Orange | 75 | 60 | 150 | 105 | 75 |
| 100 t | Orange | 100 | 80 | 200 | 140 | 100 |
/02Two slings, and multi-leg slings.
Two slings used together on one hook, or a multi-leg assembly, are rated by the same angle bands as chain and wire rope. Here the factor applies to the rating of each sling (each leg):
| Each sling | Colour | 2 legs, 0–45° | 2 legs, 45–60° | 3–4 legs, 0–45° | 3–4 legs, 45–60° |
|---|---|---|---|---|---|
| 1 t | Violet | 1.4 | 1 | 2.1 | 1.5 |
| 2 t | Green | 2.8 | 2 | 4.2 | 3 |
| 3 t | Yellow | 4.2 | 3 | 6.3 | 4.5 |
| 4 t | Grey | 5.6 | 4 | 8.4 | 6 |
| 5 t | Red | 7 | 5 | 10.5 | 7.5 |
| 6 t | Brown | 8.4 | 6 | 12.6 | 9 |
| 8 t | Blue | 11.2 | 8 | 16.8 | 12 |
| 10 t | Orange | 14 | 10 | 21 | 15 |
As with every multi-leg sling, three and four legs share one rating: on a rigid load four legs cannot be relied on to share the weight, so the factor assumes three. Make sure each pair of slings is the same capacity and length; mixing ratings in one lift puts the weaker sling at risk.
/03Webbing or round sling?
Both are polyester, both follow EN 1492 (part 1 for flat webbing, part 2 for round slings), and both use the same colours and factors. They differ in how they meet the load. Flat webbing gives a wide, flat bearing surface that spreads pressure on finished and painted loads. A round sling is a core of continuous yarn inside a cover; it is more flexible and wraps awkward shapes. Weights are close; at the light end the round sling is a little heavier:
| WLL | Colour | Flat webbing, eye and eye | Round sling, endless |
|---|---|---|---|
| 1 t | Violet | 0.4 | 0.6 |
| 2 t | Green | 0.8 | 0.95 |
| 3 t | Yellow | 1.25 | 1.3 |
| 4 t | Grey | 1.675 | 1.7 |
| 5 t | Red | 2.3 | 2.05 |
| 6 t | Brown | 2.6 | 2.55 |
| 8 t | Blue | 3.4 | 3.4 |
| Sling | Range |
|---|---|
| Polyester round sling, eye and eye | 1 t to 100 t |
| Polyester round sling, endless | 1 t to 20 t |
| Polyester webbing sling, eye and eye | 1 t to 12 t |
| Polyester webbing sling, endless | 1 t to 12 t |
/04Limits that are not in the chart.
- Design factor. EN 1492 polyester slings are rated at 7:1 — a 5 t sling must not break below 35 t. The extra margin over chain and wire rope reflects how easily a synthetic sling is cut or weakened without visible signs.
- Temperature. −40 °C to 100 °C for polyester. Keep slings off hot steel decks and out of direct sun when they are not in use.
- Chemicals. Polyester resists mineral acids but is damaged by alkalis. A blue label means polyester; green, polyamide; brown, polypropylene.
- Edges. An unprotected steel edge can cut a polyester sling under load. Use sleeves or corner pads, or switch to chain.
- Choking. Let the choke draw up by itself, and never choke a sling around a sharp edge.
Worked example: a 6 t pipe spool is lifted in a basket with two legs at about 30° from vertical. That is the 0–45° basket band, factor 1.4, so the sling needs a straight rating of at least 6 ÷ 1.4 = 4.3 t. A 4 t grey sling gives 5.6 t — not enough. A 5 t red sling gives 7 t. Use the red sling, with edge protection at any flange.
Polyester slings in this chart
Common questions
- How much can a 1 tonne webbing sling lift?
- 1 t straight, 0.8 t choked, 2 t in a basket with vertical legs, 1.4 t in a basket with legs up to 45° from vertical, and 1 t from 45° to 60°. It is violet under EN 1492.
- How much does a choke hitch reduce a round sling?
- To 80% of its straight rating under EN 1492. A 3 t yellow round sling is rated 2.4 t choked.
- Is a round sling stronger than a webbing sling?
- Not at the same rating. Both are rated to EN 1492 with the same factors; a 5 t round sling and a 5 t webbing sling lift the same. Choose on the load’s shape and surface.
- What is the design factor for polyester slings?
- 7:1 under EN 1492. The minimum breaking force is at least seven times the working load limit.
- What colour is a 10 tonne sling?
- Orange — and so is every EN 1492 sling above 10 t. The label is the only way to tell them apart.