Several different kinds of steel are used in forestry and related applications. The steel is given a grade as well as a rating or a test. The rating or the test is an indication of how much weight it is certified to handle at its specific configuration. For example, a chain might be rated up to 12 tonnes. This means that it will work for applications up to 12 tonnes. If it’s not the only chain in use, it can be used for more than 12 tonnes of weight, but that’s still not advisable. In addition to the rating or the test, forestry steel is given a grade. The grade is not a measure of quality but instead an indication of composition and creation process.
The grade of steel indicates the materials of which it is comprised and how it was forged. For example, grade 80 steel is typically boron alloy steel. This means that the steel is forged with boron mixed into the steel. Also, it is usually a microalloyed steel. This means that it is made with trace amounts of boron instead of large amounts as you might find in a carbon steel. The introduction of other materials is so potent that trace amounts of boron completely change the character of the steel. That it is microalloyed typically means that it is cold forged. Because it is cold treated and not tempered, it lacks the ductility of other types of metal. It is solid and rigid throughout without a pliable core. This type of metal is often used in forestry; you can sometimes find it used in chain slings that are used in forestry applications.
A sling is very popular for use in forestry because forestry often involves materials that do not easily attach to a crane or a pulley. In industrial applications, you can often attach items via eye bolts or hooks. In forestry, the chains often have to be wrapped around tree trunks, large branches, and so on. To do that, you might employ a sling that can be wrapped around the item. Also, a sling spreads out the weight of the item that you’re lifting.
That’s especially helpful when you’re lifting long items such as tree trunks. Since they have such a wide balance of weight, it can be difficult to lift them and balance them with just one point of contact on a chain. A sling offers you several points of contact for better balance.
Also, a sling can increase the test of just about every kind of steel. One chain might be rated for 10 tonnes but a sling made of those chains can often lift more than 10 tonnes. It is a way of multiplying the usefulness of your chains without having to buy new ones.