I was wondering what the best way was to cut the B post in vehicles. I run with two different departments, one EMS that does extrication, and one fire that does extrication. With my fire company, I was trained not to cut directly on the B post for fear of hitting the seatbelt pretensioner and instead cutting with a wedge. When training with the EMS agency they go right for the B post. Which is correct? What will occur if the seatbelt pretensioner is hit?
1st thing is to get all the plastic off the interior of the post and you can see what you are going to cut through. Usually you will be okay to cut the post.
If you do hit the pre-tensioner...well, you might be in for a surprise. ;)
I agree completely with taking the plastic off. With all these new cars on the road today it's hard to say what you'll find behind there.
Pretentioners are bad. Airbag gas cylinders are even worse!
I have made it a standard practice in my department that plastic be removed no matter where they're cutting. By removing the plastic; not only will you find any hidded hazards, but you can see factory relief holes in the metal. It may take a few extra seconds before cutting, but if it saves a firefighter from injury or death it's completely worth it!
You dont state where you will be cutting the B post. Taking off all the plastic is a must these days. If your cutting high on the post, there should be no problem. If your cutting low, the pretensioner comes into play. But if you cut high, you must be aware if the vehicle has side impact air bags. And if you wedge cut low, say on either side of the post at the rocker panel, you must watch out for gas lines and baterry cables that may run through the rocker panel.
You guys hit the nail on the head about removing the plastic on the interior of "ANY" post you are going to cut! "A" and "C" posts also have airbag canisters in them too.
One thing that wasn't mentioned is removal of the plastic before cutting even in the absence of pretentioners and canisters. What about the large reinforcment involved with a sliding seat belt anchor? A quick look and a chalk mark, above or below the reinforcement, could make the difference between a simple cut and one that is more difficult.
AS an alternative, I've seen some cut the bottom of the door sill in a V shape around the B pillar. (Does that make sense?) They then remove the pillar intact with all the gadgets still inside...
All good advice. This is What I termed the "strip search" on the interior in our SOG's. Meaning take the plastics off the inside of the pillars/posts and roof rails. This is the best way to "visualize" where NOT to cut. Once the inflators or pre-tensioners are spotted the we "score" the upper end and lower end of the devices on the outside of the pillars and cut above or below the marks just NOT BETWEEN the marks. This really helps for external markers for all rescuers. Lukes advice on cutting the base of the B-Pillar is excellent advice as well and works well as either a primary or secondary option whether cutting or performing a B-pillar "blowout" with the spreaders.
I beleive Lutan is describing the "wedge" cut that Bvafire mentions. I will add my vote to the need to clear the plastic inside before you cut. Thinking back to the "old days" we probably should have been teaching this all along just to help find the reinforced areas of a vehicle to avoid when making cuts. Had we done that, the new hazards of pre-tentioners and SRS cylinders would not have been such a big deal.
No one has addressed what the dangers are when you cut into a pre-tentioner. I am not sure I recall ever doing this, but I do recall cutting into a recoil spring on a safety belt. It made a lot of noise as it uncoiled that didn't set well with the victim or the rescuers (myself included), but it did not present any serious problems for us once we calmed down.
Not cutting directly into the B-pillar but instead cutting the roof rail at the connection point of the B-pillar is something someone came up with a few years ago when the word got out that HSLA (high-strength, low allow steels) were being placed inside some B-pillars. It is by the way but still only on a small percentage of vehicles even through 2005 model year. The fear was that we could not cut through a B-pillar anymore with this strong steel inside. The roofrail cut that was mentioned in earlier posts is an inverted 'V' that when successful, allows the pillar to come free of the roof. I'm not too fond of it.
Ironically, Volvo for example, who use HSLA in their B-pillars also have that HSLA metal extend 6" - 8" on either side of the roofrail at the B-pillar attachment point. The inverted 'V' cut wouldn't be cutting into the HSLA inside the pillar but it would be cutting into the HSLA of the roofrail; same difference.
B-pillar cutting should begin with stripping the trim. From that point, you'll see what you've got. If there are factory "holes" in the B-pillar, I can almost guarantee you can cut through the pillar; no HSLA. They don't put holes in HSLA-reinforced B-pillars; they're a solid or smooth sided pillar.
Use a good quality recip saw with a metal cutting blade. If you use your hydraulic cutter, open the blades so its' rearmost notch or cut point does the cutting; not the tips. The 'crotch' of the cutter is where it is the strongest.
Avoid cutting into seatbelt brackets, mounting bolts, etc. An earler post mentioned cutting a seatbelt pretensioner as a "bad thing". This is an incorrect statement. The only pretensioner design mounted up high on the pillar would be a cigar-shaped design pretensioner. The exposed cable coming out of it and running to the spool for the seatbelt system can be cut through without a problem. The cigar-shaped unit itself is not pressurized. It does have a small chamber of black powder in it but I'd cut through it if I had to.
The only other design of pretensioner mounted on a B-pillar is a pretensioner that is mounted to the take-up spool. There is No reason to cut this unit; it's mounted directly onto the seatbelt take-up spool and to cut it would mean you're also cutting through the seatbelt and the spool itself. That's not a realistic rescue thing to do.
As far as cutting a 'V' in the rocker channel of a vehicle to remove a B-pillar, I strongly suggest you do not do this. You want to maintain the integrity of that lower structure for a long as you can. Cutting it can ruin the efficiency of any future dash jacking or dash rolling tasks you may have to do.
Any anyone who ever tells you that there are airbags mounted 'ON' a B-pillar is incorrect. I hear this a lot and it's not true. There are airbag deployment sensors and some airbag IDs but no airbags are secured directly to any B-pillar! Seats, doors, and roofrails; but no B-pillars.
Very good statement on B-Pillar cutting, Ron!
As you said, the cutting technique is important when you use the hydraulic cutter. Firefighters often tell me that they could not cut through posts, in most cases there was a lack of user knowledge and it WAS possible to cut through the structure. Many people do not wait until the hydraulic pump has its maximum pressure or do cut with the tips of the cutter and so on...
What I don't like are some of the keywords that are often used, such as HSLA and boron steel. These are words used by some of the manufactures marketing (volvo, saab) but not by all. I think its important for firefighters to know where there could be reinforcements, but its not possible to identify the type of steel at the crash scene. So, keep it simple! I think its the same with the different types of airbag-gasgenerators, is it necassery for a firefighter to know the different types? I say not, he must be able to identify the generator and he must knowe not to cut into it... keep it simple!
Be alert that their could be a gas generator for a curtain style airbag at the roof rail area above the b-post when you use the inverted V-cut.
Ron, did you get my email regarding the porsche head airbag?
Ron, I was reading your post, great information. My question is related to the cutting of the V in the rocker panel. If it is necessary to perform this type of cut knowning that a dash lift or roll may needed should we place cribbing under the rocker panel to reduce the potential of the rocker panel from collapsing. Is this a practice that is being used in your size up. I have seen several rocker panels collapse because of the situation you describe. Stay Safe.