DuPont flexible sling — What the Fibre Decides, and What It Does Not

1. The Three Names, and What Each One Describes

The page is listed under three names, and they are the same family seen from three sides: the material in front, the form in the middle, and the shape at the end. Reading them as one name is what causes most of the confusion about this article, so it is worth separating them before anything else.

A high performance fibre article in the circular form. This is the factory's own photograph, placed here because the two things a buyer can see - the soft construction and the loop - are exactly the two things that the fibre name in front of the product does not tell you.

2. What the Fibre Decides

A high performance fibre is bought for one of four reasons, and it is worth knowing which one applies before the article is specified, because the four pull in different directions and a single article cannot be best at all of them at once.

3. What the Fibre Does Not Decide

The rated load is not a property of the fibre. It is calculated from the material strength, the design factor, the type of hitch, the angle of loading, the diameter of curvature over which the article is used, and the efficiency of the fabrication - and only the first of those six is about the yarn. Four of the six belong to the way the lift is made and the way the article is made up, which is why two articles with the same fibre and the same nominal capacity are still not the same article.

4. How to Buy a Branded-Fibre Sling

The practical rule is to buy the specification and not the name, and the reason is not scepticism about the fibre: it is that the name in front of a product is not a rating, and a quotation that answers with a name has not answered the question. What a buyer should ask for is the fibre type, the construction, the rated load per hitch and angle, the marking, and the test and the certificate that come with the article.

One point of law and manners belongs with this, and it is the reason this section exists at all: the fibre brands named in this trade are the property of the companies that make the yarn, and this article is made by us from yarn bought from the fibre supply chain. The brand is used here and in the product name to describe the yarn, not to claim that the article is made or endorsed by that company. Where a customer needs the yarn's own certificate or a stated yarn specification in the order, we will say what can be provided with the article and what has to come from the yarn supplier.

5. Fibre, Weight and the Job of Carrying the Article

The first thing a high performance fibre buys is not strength in the abstract but mass that is not there. At the heavy end of the range an article that has to be carried to the load, dressed round it, folded and stored is a handling problem before it is a lifting problem, and the lighter construction is what makes a 60 metre lift possible for a rigging team rather than a machine. The point is not that the article becomes light; it is that the article stops being the constraint.

6. Fibre and Stretch, Which Is Not the Same as Conformity

A high performance fibre is also chosen for what it does not do: it stretches very little, which keeps the headroom predictable and the landing of a load under control. That property is different from the article's conformity - a soft article lies into a curve while a low-stretch article does not lengthen - and the two are confused constantly. The circular circular lifting belt page separates them.

7. The Envelope, Which Is a Property of the Fibre

Temperature, light, moisture and chemicals act on the fibre before they act on the article, so the envelope has to be settled with the fibre in mind and then reconciled with the published figures for the market the article is sold into. For polyester and polyamide the published guides give minus 40 to plus 100 degrees C, the guidance for synthetic slings gives 90 degrees C as the upper figure, and the regulation gives 180 degrees F for polyester and nylon; work to the lowest figure that applies. The WLL 150T polyester round sling page sets out the reconciliation. Chemistry follows the same logic: nylon is excluded where acids or phenolics are present, and polyester and polypropylene are excluded where caustics are present, and a high performance fibre has its own exclusions, which we will state for the yarn actually used rather than generalise.

8. Inspection, and the Same Rules as Any Other Sling

The schedule does not change because the fibre is exotic: each day before use, periodic inspections at intervals no greater than twelve months, and additional inspections where service conditions warrant, judged on the frequency of use, the severity of the service, the nature of the lifts and the experience of the service life. The conditions that remove a sling from service immediately include acid or caustic burns, melting or charring, snags, punctures, tears or cuts, broken or worn stitching and distortion of fittings. A repair, where one is allowed, is a manufacturer's repair followed by a proof test to twice the rated capacity, with the repair marked and the certificate retained; load-bearing splices are not repaired and temporary repairs are prohibited. The class page sets out where that leaves this family against the chain family, which can be repaired and re-tested where a synthetic article is retired.

9. What the Enquiry Has to Carry

10. Frequently Asked Questions

Contact

Send the six lines in section 9, and say which of the four reasons applies, because that is the one that decides whether the fibre is worth paying for in this lift. Articles are batch tested, marked per hitch and supplied with a certificate that names the article.

• Telephone and WeChat — 18066002268

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• Address — Lifute Industrial Park, Taizhou City, Jiangsu Province, China