Synthetic Sling Basics
Part 2 In a Series By Andy Slater

Like shackles, synthetic slings are an important part of your toolbox.  And like any tool, it must be stored properly and taken care of.  In the following article I will discuss the different types and sizes of synthetic slings.  I will also discuss proper use of slings.  I will limit my discussion to synthetic slings because the use of other types is usually not recommended in pulling applications.  The wire rope and chain slings are less forgiving and do not have the shock absorbing properties of the synthetics.  The synthetic slings will actually aid in pulling someone out by stretching and retracting and actually doing some of the work for you. 

TYPES/SIZES

There are two main types of synthetic slings the polyester round and nylon web.  Both have many uses in the off-road arena.  The round sling is often considered more versatile where as the nylon sling is generally used for lifting and pulling.  I often use the round slings for hanging my hammock at the campsite. 

Round slings are manufactured in a continuous circle from polyester filament yarn.  This is then covered in a woven casing.  All round slings are made in circumference sizes, twice the length of the diameter.  Round slings are pretty simple and self-explanatory.  The nylon slings on the other hand offer many options.

There are a number of options when choosing a nylon web sling like the type of eyes, length, width and the number of plies.  Or in my case, you get what you can find. 

Though you probably don’t think about it, there are a number of options when choosing the type of eye you want on your sling.  Type 1 - TC Slings have a triangle fitting on one end & a slotted triangle fitting (the choker) on the other end.  This is most commonly used in a choker hitch, but can also be used in basket and vertical hitches (1 Hanes Supply, Inc. Website).

Type 2 - TT Slings have a triangle fitting on each end.  Used in vertical and basket hitches only (basket hitch being most typical).  Type 2 slings are more economical than type 1 (1).  These are really good slings for creating a basket hitch around a tree to protect it.

Type 3 – EE Slings have eyes at both ends – choice of straight or tapered eyes (tapered eyes are standard > 2” web-width).  Flat Eye slings are very popular slings, which can be used in all three types of hitches (i.e., Horizontal, Basket or Choker) (1).

Type 4 – EE Slings or Twisted Eye slings are similar to Type 3 except the eyes are twisted to a 90 degrees right angle to the sling body to form a better choker hitch.  This type of eye also nests together better when used in a basket hitch (1).

Type 5 – EN or Endless slings, sometimes also referred to as grommet slings, are very economical.  These are very similar to the round sling except they are made of the synthetic web instead of the polyester filament yarn.  They can be used in all three types of hitches and wear points can be moved to increase sling life (1). 

Type 6 – RE or Return Eye sling is also referred to as Reversed Eye Sling.  Sling body is formed by 2 parts of webbing sewn side-by-side using either a cordura tube or web in the finished width creating a protective webbing over the entire body and eyes.  This extra webbing reinforces the sling and protects it from wear, resulting in an exceptionally strong sling (1).

The rest of the options available when choosing a sling are self-explanatory.  The length of a sling is determined by measuring from eye to eye.  On a round sling this is done by stretching the sling out and measuring the inside diameter. 

When choosing widths you have many options.  The most common widths are 2, 3 and 4 inch.  Some slings can be as wide as 12 inches. 

 The last option is the number of plies.  The different slings available are 1, 2, 3 and 4 ply.  The more plies a sling has the stiffer it gets.  In most cases a 1 or 2 ply is sufficient for pulling someone.  The number of plies a sling has is a big factor when rating the capacity.

Now that we’ve covered the options that are available when choosing a sling we need to go over how to use one safely and how to determine if a sling shouldn’t be used. 

PROPER USE

Like shackles, when a slings capacity is rated it is done within certain guidelines.  Any deviations from these operation guidelines will greatly reduce the capacity of the sling.  Earlier in the article I talked about three different ways of hitching a sling.  When rating a sling it is done using the three types of hitches.  The three hitches are the vertical hitch (or in our case horizontal), choker hitch and basket hitch.  

For instance, a 3” X 30’, one ply, and type 3 sling has a vertical capacity of 3,600 to 4,800 lbs.  This would be the typical use for a sling in our situation. 

The basket hitch capacity for this same sling is 7,200 to 9,600 lbs.  The rated capacity for the sling nearly doubles.  A good application for the basket hitch is when you’re using a tree for anchor point for your winch.  Keep in mind that the rated capacity increases when you go to a 2, 3 or 4 ply sling. 

The rated capacity for this sling using a choker hitch drops to 2.900 to 3,800 lbs.  The reason the capacity drops so much is because of the pinch in the sling.  So the next time you want to use a tree for anchor point think about the type of hitch you will use.  Not only does the choker hitch put the tree in danger by choking it.  It puts you danger by reducing the rated capacity of the sling. 

When using a sling it is important to remember it is under a lot of stress.  When a sling is used in manner other than the vertical or basket hitch the rated capacity can drop tremendously.  Just laying it over a rock when it is under stress not only causes an abrasion hazard but also can reduce the capacity as much 70%. 

ONE LAST THING

Most slings are designed with a wear indicator imbedded in it.  A wear indicator in most cases is a red thread that runs up the edges of the sling.  On a typical jobsite the sling is removed from service when this red thread becomes visible.  For many of us that is how we get our slings.  If the Occupational Safety and Health Administration (OSHA) discovers a sling on the jobsite with the red thread visible it could mean heavy fines for the company.  In most cases these slings can be used to pull individuals but remember the capacity is reduced because of the break in the webbing. 

Just like any other tool in your arsenal, maintain your slings.  Keep them in dry places and don’t use them in manner other that we’ve discussed today.