Extrication Education: Technology 101 - High strength metals


CarolinaFireJournal - David Pease
David Pease The Reds Team
04/23/2012 -

Most departments cut back on their extrication training during the winter months, and then crank up in the spring. Training declines some in the dead heat of summer, then usually picks back up in the fall.

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A problem I see departments facing is getting the cars they need to train with. With metal prices up, folks are reluctant to donate cars to be used for extrication training. One consideration is getting together with your neighboring departments and coordinating your training between the two organizations. This may help get the cars you need.

I’ve found that going to the salvage yard to train is always a better option. I do realize that may take you out of your district, however, I am sure the department next to you would be willing to cover your district while you train for the day. It is all about working together for the betterment of the whole.

Last issue we looked at seatbelt tensioners, curtain bags and knee bags. This time let’s look at some of the features that could make our job a little more difficult, but with the knowledge and skills we can overcome them.

One new feature found in a lot of your newer vehicles is the use of “Boron” steel or other high alloy steels and metals. These metals are lightweight but “extremely” strong. We first started to see these types of metals in the side impact rails. The older style rails were corrugated, wide and heavy. The new rails were tubular, strong and lightweight. From the side rails the high alloy steels were starting to be used in the dash assemblies and then saw its way into the post and roof framing. This makes the vehicles stronger when it comes to crashes. It always seems that when they make things better for the consumer, it makes things tougher for us as the rescuers.

A word about metallurgy — the science of metal and steels. The newer metals, and the processes they use to make them would be way more than we want to get into, and would not really help us that much. But understanding a little about the metals might give us an edge when it comes to extrication.

We all understand PSI, or pounds per square inch. This is something we gauge our extrication tool’s capability with. So how does that apply to the metals in the vehicles we encounter? The basic metals we found in older vehicles had a PSI range of around 25,000 to 40,000. These metals were referred to as medium strength, low alloy or MSLA. In newer vehicles we now find HSLA metals, or high strength, low alloy. These metals have ratings from 40,000 psi to 75,000 psi. They also comprise up to 60 percent of some vehicles. These HSLA steels have been around for decades, but have only seen their way into automobiles in the last 10 to 15 years.

Now along come dual-phase steels, that have a PSI range from 75,000 to 150,000. There are even higher strength steels available that go from 115,000 psi to 215,000 psi. Luckily for us, the formability of these metals make it difficult and costly in most vehicles, so we will not run across these very often, if at any.

You now have a little better understanding of what is being used to construct new vehicles, and more importantly, the kind of strengths you are dealing with. The problem is now being able to cut through this high alloy steel.

Over the past several years I have run across departments that have told me of extrications they were involved in that they were unable to cut the post or framing and had to look at alternate methods of extrication. Earlier models and parts of some of the newer models will have steels that can be cut at 25,000 to 40,000 psi. This means that as long as the cutter can produce these pressures at the point of cut, you can cut it. Even the HSLA steels only go up to 75,000 psi which “most” of the new cutters can handle.

However, the older model tools with capabilities of only 30,000 to 40,000 psi, will not do the job. If you encounter the dual-phase metals, the cutter will have to produce up to 150,000 psi. The other thing to keep in mind is that even though your cutter advertises it has 150,000 to 200,000 psi of force, it has to produce that at the point of contact to cut the metal. The highest pressures produced by the cutters, are toward the hinged section of the cutter tips. The more you can get into the cutter, the better it will cut. Cutters will develop their full potential at the tips.

As you can see, with the onset of these higher strength alloy steels, they make vehicles lighter and also stronger. Over the past 10 years the average automobile has dropped in weigh by 1000 pounds, but increased in strength. You, as the rescuer, need to make sure your equipment has the capability to cut these newer metals and you may need to modify your technique. If you are not able to get your cutter in deep enough and it is not making the cut, consider crushing the metal with your spreader and then proceeding with the cutting maneuver. You have to get the cutter in deep for its maximum capability. I haven’t had a chance to test out some reciprocating blades on the HSLA steels, but I have my doubts on how they will perform. When I do get a chance to test a few of the better blades, I will pass on the results to you.

Vehicle extrication is an ever changing technology and we have to stay on top of things if we want to get the job done. Read up on all you can, and keep practicing. Until next time, stay safe and train hard.

If you have any questions or comments e-mail David Pease at [email protected] and visit the team website at www.RedsTeam.com.
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