How to Proof Test a Synthetic Round Sling

Intro

So if you walk on any job site in this entire country, and you see anything up in the air, chances are, it’s slings that hold them there. But what is the working load limit? What does it take to break them? And in this episode of the Rigging Professor, we find out.

What’s up guys? Devin here from Mazzella Companies and today, we’re going to break a synthetic round sling. We think it’s important because you need to know exactly what the working load limit is of your synthetic round slings and what happens if you overload them.

And to test this, I brought in some help. That is a buddy of mine here at the Cleveland office, and I set him on the floor here at Cleveland HQ to work with a guy named Jason. Now, Jason is our proof tester. His job is to make sure that slings, chains, whatever, get tested so they can do exactly what they’re rated to do.

And then he maxes them out to see when they break and if they broke where they should have. So I’m going to pass it to Thad, and he’s going to start by telling you the different tests a synthetic round sling goes through before you’re ready to buy.

How to Proof Test a Lifting Sling

I found Jason inside and he told me there were two tests to make sure my synthetic round sling was safe for the field. The first, before it goes out to the field, is called a proof test.

What we do in the proof test is we take the vertical working load, which on this particular sling is 5-to-1. So the working load of this is 5,300, and we take that, we pull it up to two times the working load, which would be double that number, hold it for about 10 seconds, and then bring it back down.

The machine used to test the sling has a carriage for pulling and a carriage for holding. A pin is dropped down to hold the sling in place on the pull side and on the hold side. Make sure the sling is untangled, close the gate, and we’re ready to test.

The pulling carriage slowly puts pressure on the sling. In our case, 10,600 lbs of it. And for the proof test, hold steady at that number until Jason ends the test. We inspect the sling for any damage, like tears or holes, and if it’s clean, it passes.

We took it to the vertical load, two times, which was 5,300 times two, and what that does is just make sure that it’s working properly and that it was made right. The customer normally only goes by these numbers just to keep them safe.

So this is safe to use now in the field? Yep, this is perfectly safe to go to the customer.

During the proof test, if something were to happen and it wasn’t safe, what would happen? Well, if it wasn’t safe then it would fail, and then after that we would go to our inspector. Ryan Gara would look over it and find out why it failed.

How to Break Test a Lifting Sling

So the next test we want to do is a break test. So how does that work? Well, a break test is when we take this all the way to maximum breaking strength, which is the 5-to-1 ratio, and for this particular sling, I believe it is 26,500 lbs. So, 26,500 lbs, this should go boom.

The break test is set up the same way as the proof test, but instead of holding at a certain point, the pull carriage keeps on pulling until the sling fails.

Wrapping it up

Alright, so where did this thing break? Okay, this thing broke at 33,100, so it broke at about 10,000 lbs over the manufacturer breaking strength, so that’s excellent. Yeah, excellent.

So what we do next is we remove the pin, take it out, and look at the damage we got. This one pretty much broke underneath the sleeves, as you can see here. These are all the fibers that give us all the strength. These fibers would normally be nice and smooth; they’re all bunched up because they popped.

If it broke below the break point, we probably would pull out a few more and break those to see where those break to get an average breaking strength. Okay, yeah, that makes sense.

Closing

That’s it for today’s episode. And I do hope that we were able to better help you understand the process a synthetic round sling goes through before it’s able to be sold to you.

If you liked this video, consider checking out the rest of our Cranes 101 series, or the Rigging Professor as well. There’s a ton of content there, and we’re going to make a whole bunch more. And if you subscribe to our channel, you won’t miss out on any of it.

If you have any questions, or if you need help on your next lifting project, don’t hesitate to reach out to one of our lifting specialists. They’d be happy to help you however they can. Thank you for watching.