Another view on torque testing bulkhead

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Another view on torque testing bulkhead

October 30, 2012, 12:49:26 pm

Talking to Rance at Xtreme, he cautioned about trying a torque wrench to test a bulkhead, that it is not really the best method. I realize that much of the discussion in the Forum has centered around such testing but if I understood Rance correctly, there is a danger of twisting off a bolt and causing a problem when there was not one. My friend Don C. suggested then maybe you try much less than the 250 lb-ft torque that you use to install, maybe 175, to see if it falls off. Don Hay had some ideas too, that it is necessary to try some level of pressure. So, maybe if you are about to try the 250 lbs-ft jsut to examine, you get some other information before going to that level just to test.

Rance, as I heard him, suggested that good visual inspections would be a good place to start. Look for bending along the seam, there should be none. Look for missing bolt heads or those that you can turn easily with a small wrench, look for separation. I am sure I do not have all of his ideas on this so others can add what to look for at prior threads or beamalarm. This is just a cautionary report to not trying the full torque as a test if you have that in mind. Mike

Re: Another view on torque testing bulkhead

Reply #1 – October 30, 2012, 01:38:02 pm

Totally agree with Rance. Applying much pressure either way to one of the bolts may weaken or break a bolt that is already damaged and is rusted in place. A bolt in this condition already has lost part of it's strength. Any missing or broken bolts indicates rust on the backside of the big angle iron. Mine looked great from the visible side but had extreme rust and the expansion from the rust is what broke the bolt.

To do a temporary repair, each bolt could be removed with a more suitable bolt with corrosion protection installed. The bolts that break should have holes drilled next to them with either grade 5 or 8 galvanized or 316 stainless bolts with nuts installed on the back side. A more permanent repair would see a line of bolts removed, the angle iron wedged out a half inch or so, the rust removed from the back side with any remaining rust sandblasted and spray galvanizing applied. Not that hard to open the back side through the foam and install the nuts. I didn't seal the bottom of the angle iron/bulkhead joint on ours as I was concerned that water could find it's way in from the back side of the vertical members and be trapped inside.

I could bring a grade 8 replacement bolt up to full torque without deforming the square tubing under the nut/washer but had no rust damage to the tubing.

For those who might minimize the amount of rust possible on the back side, our angle iron was eaten half way through in some spots. All on a very clean coach without any time up north. See photos on my earlier posts to see the amount removed. Again, the angle iron had an excellent appearance on the bolt head/visible side.

While adequately strong when new, this design along with the bolts used, is prone to corrosion damage as the years go by. Eagle buses also had rust problems in their early models and required frequent welding and tubing replacement so our Foretravels are not alone with corrosion issues.

Pierce

Re: Another view on torque testing bulkhead

Reply #2 – October 30, 2012, 01:39:36 pm

Mike, actually it's "inch" lb's. Which equals about 21 Ft. lb's .

Dean

Re: Another view on torque testing bulkhead

Reply #3 – October 30, 2012, 02:12:59 pm

What? What in/lbs equals ft/lbs The confusion fomented by the difference could be disasterous!

Re: Another view on torque testing bulkhead

Reply #4 – October 30, 2012, 02:47:10 pm

12" = 1' (12 inches = 1 foot)
12 inch-lb = 1 foot-lb (12 inch-pounds = 1 foot-pound)

12 inch-lb = 1 pound of force exerted at 12" from the center of the bolt
12 inch-lb = 1/2 pound of force exerted at 24" from the center of the bolt

240 inch-lb = 20 foot-lb = 10 pounds of force exerted at 24" from the center of the bolt
or 20 pounds of force exerted at 12" from the center of the bolt

You could measure it with an ordinary wrench and a fishing scale, but it's much easier with a torque wrench. My old Craftsmen torque wrench is calibrated in ft-lb and kg-m. 250 inch-lb would, as Dean suggested, be about 21 ft-lb.

Re: Another view on torque testing bulkhead

Reply #5 – October 30, 2012, 03:17:08 pm

I have the Oshkosh Truck chassis so we don't have the bulkhead issue but I wonder:

When I designed large metalworking machines one of my rules was: "If I can't keep the chips and coolant out, then let them out."
Would it be advantageous to create an air gap by using spacers or something in order to reduce trapped moisture creating the rust issue??

(bored with no coach to work on so maybe someone might want to follow up on this?)

Re: Another view on torque testing bulkhead

Reply #6 – October 30, 2012, 04:17:57 pm

Since the angle iron is much larger than the tubing it bolts to, a 1 1/2" diameter, 1/4" thick or so spacer might just have done the trick with each bolt passing through one. The air gap would not allow any debris or water to collect there .

Not a bad idea you have. Certainly worth thinking about.

Pierce

Re: Another view on torque testing bulkhead

Reply #7 – October 30, 2012, 04:37:53 pm

Sorry, have to disagree.

If that grade 8 Rolok bolt doesn't torque to 250 IN-LBS (YES, that is INCH POUNDS) is certainly is NOT holding together your Foretravel.

From a practical standpoint from checking hundreds of them, every one that did not torque had absolutely, positively been broken for a long time. Long enough that the surface of the break was well-rusted. I have yet to have one not torque and pull it out to find a fresh break.

Now, if someone asked him about torquing to 250 ft-lbs, I quite agree with him-- that would be a VERY bad idea. 20.8 ft-lbs (250 inch-lbs) is quite different from 250!

And, as far as gaps, please look at the "lock washer type serrations" on the Rolok. They allow free migration of water into the thread area unless sealed with undercoating, etc. See my initial write-up.

Brett

Re: Another view on torque testing bulkhead

Reply #8 – October 30, 2012, 05:42:08 pm

Brett,

I tried removing my Roloks but have had success with only one. The rest broke off when I tried to remove them and show a nice, clean break on the face. That can only indicate the threads have rusted together where they pass through the first side of the 1 1/2" square tubing. It would also indicate that the Rolok had lost part of it's strength. This is the point other bolt manufactures make when they advertise their specification for corrosion resistive coating compared to a uncoated Rolok type bolt.

As far as water seeping in through the serrations, I think the majority of water comes down from the top of the angle iron. My rust was not centered around the Roloks but distributed evenly down the entire length of the angle iron. In no way does the angle iron seal against the bulkhead to keep water out at the top in fact, there is no really pressure there compared to further down where the bolts are located.

Pierce

Re: Another view on torque testing bulkhead

Reply #9 – October 30, 2012, 08:41:13 pm

sorry about ft/inch lbs....I obviously do not have a torque wrench....but to someone reading this, thinking about how to help prevent this damage, this is one source I have heard and I am sure it is in some threads.

When you fill the fresh water tank, if you overflow it, the water runs into the seam of the bulkhead metals. Do not allow. Now I cannot say for sure that happens on your coach, so ask someone. But I gather it is pretty universal so advice......try to avoid overfilling the fresh water tank. I am pretty sure that can happen on our 2001.

I recall someone told me one time they installed an overflow pipe into the top of their fresh water tank to route that water away from the bulkhead. Stewart told me to just watch the level in the tank as I fill the tank, but I do not believe that I can see that through the plastic of the tank.....I will try to monitor that way. Perhaps you can though, give it a try if not doing.

Also, from a bit of perspective, I wonder if the overflow threat is very minor versus simply the water off of a rain on the highway. Our prayers for the folks in Sandy's path, Mike

Re: Another view on torque testing bulkhead

Reply #10 – October 30, 2012, 11:46:58 pm

Mike, there is a lot written on our Forum about re-routing the fresh water tank overflow hose.

We can easily see our water level as we fill the tank, as our tank translucent and a florescent lamp laying on the top of the tank shows just where the water level is.

How about undercoating the top of the bulkhead angle that runs side to side? Walmart sells 3M spray can undercoat.

Re: Another view on torque testing bulkhead

Reply #11 – October 31, 2012, 12:05:03 am

Hi guys.....well, when I get the motorhome back from Xtreme......still repairing from the collision that took out the windshields, gen door and some dash work.....I will see how/where I can put that lamp. Sounds like a great idea. But memory serves I can not see the top looking in the utility bay.

Probably not a way to use with an existing bulkhead? But Rudy introduced me to Corrosion X and I know it could be used in rebuilding a bulkhead, not sure in existing one and it not a sealant anyway like the 3M. But I mention it to anyone reading this thread and does not know about Corrosion X (I think I could have sold several cans during a stay in a park this summer).

Thanks again for the info on the overflow rerouting. Mike

Re: Another view on torque testing bulkhead

Reply #12 – October 31, 2012, 12:25:31 am

Mike,

CorrosionX is used to kill and corrosion protect metal that you do not wish to paint. Examples are electrical connections, circuit boards and any metal that needs protection and lubricating such as drawer slides and the metal folding steps on some coaches.

Ospho, a dilute solution of phosphoric acid is what James Stallings used on my bulkhead to chemically react with ferrous oxide to turn it into ferrous phosphate, an inert salt, killing the corrosion on the metal that we wished to paint. Ospho leaves a primed surface when it dries and now only needs a top coating to seal the surface from the elements.

So my bulkhead was cleaned, soaked in Ospho, clamped together with bolts and painted to finish the job.

Hope this helps define the uses of these two outstanding products.

Re: Another view on torque testing bulkhead

Reply #13 – October 31, 2012, 12:34:14 am

Rance introduced me to Corrosion x and aspho. I am on my last can of C X and want more but cannot get it here in BC Canada. I have used the Ospho on many projects at home and it is great and paint sticke to it like s--t.

John h

Re: Another view on torque testing bulkhead

Reply #14 – October 31, 2012, 09:42:40 am

Quote from: John Haygarth – October 31, 2012, 12:34:14 am

Rance introduced me to Corrosion x and aspho. I am on my last can of C X and want more but cannot get it here in BC Canada. I have used the Ospho on many projects at home and it is great and paint sticke to it like s--t.

John h

John,
Check Aircraft Spruce for Corrosion-X. I bought some in a 16 oz. hand squirt container. This link shows the aerosol, call to see if other is available if you want hand squirt container.

http://www.aircraftspruce.com/catalog/cspages/corrosionxoriginal.php?clickkey=9905

Re: Another view on torque testing bulkhead

Reply #15 – October 31, 2012, 10:11:07 am

Skygeek.com is also a good source for Corrosionx. They also carry Simple Green Extreme with competitive prices on most items.

D&D

Re: Another view on torque testing bulkhead

Reply #16 – October 31, 2012, 11:21:22 am

I only remember one report of a total bulkhead failure and that was a rear bulkhead about a year ago. I cannot find a definitive result on the cause of that one. Does anyone know of any other true bulkhead failures and or what actually caused the one reported on here?

Re: Another view on torque testing bulkhead

Reply #17 – October 31, 2012, 11:43:15 am

Kent,

No, I don't recall that the owner of the one in S Texas that totally separated ever came back to post a follow-up.

There was also the complete separation of the front bulkhead where the fuel tank was visible below the basement floor.

I have seen two others where bulkhead separation was bad enough to cause cracks in the sidewall of the coach. Again, that is a very small percentage, as I have looked at a LOT of Foretravels over the last decade and a half.

But part of the answer depends on what you would classify as failure. I have seen several others where you could stick your fingers in the separation between angle and box beam. I would suggest that is also a failure.

Warning signs I look for in addition to checking bulkhead bolts for torquing to 250 inch-lbs:

Signs of corrosion or any separation between angle beam and box beam. I got a photo last night of a bulkhead taken by another Foreforum member with a car ignition key stuck into the separation of the bulkhead. That can't happen unless there is a problem.

Signs of corrosion around the trap door in the wet bay, as it indicates a common entry point for water.

Another common entry point for water is on coaches with shore power cord reels. Have seen several where the reels were bolted through the floor (remember thin layer of fiberglass, foam core and than layer of fiberglass). The weight and motion of the reels broke the washers/bolts through the bottom layer of fiberglass, opening 4 $.50 size holes in the bottom. Easy fix is to clean out, remove the water soaked foam core and use a larger metal backing plate (aluminum is easy to work with) that both covers up the hole and spreads the load over a larger area.

And sign of water in the wet bay-- check floor of both sides of wet bay (first basement doors forward of rear wheels).

Preventive measures: Several have reported that the top of their angle beam is NOT sealed, allowing water down into the bulkhead. If not sealed, 1/4 can of spray undercoating (after cleaning) will easily seal it.

As previously discussed, the heads of the Rolok bolts have serrations that allow water migration into the bulkhead. Wire brush the angle. Use tape to protect head of bolt from undercoating. Undercoat the angle at least in the area where the bolts are.

If your fresh water tank drain exits into the wet bay, re-route it through basement floor.

As with any coach, if you drive on roads with salt, do a good job of washing the undercarriage (and CAC/radiator)

ABSOLUTELY, POSITIVELY KEEP WATER OUT OF THE FLOOR OF THE WET BAY.

I have seen 20+ year old Foretravels with PERFECT bulkheads, and I have seen much newer ones where a leaking $.15 gasket on the fresh water intake had soaked the bulkhead to the point of separation.

There is noting mystical about the bulkheads. A little attention do detail and they are good forever.

Re: Another view on torque testing bulkhead

Reply #18 – October 31, 2012, 12:03:40 pm

Quote from: Kent Speers – October 31, 2012, 11:21:22 am

I only remember one report of a total bulkhead failure and that was a rear bulkhead about a year ago. I cannot find a definitive result on the cause of that one. Does anyone know of any other true bulkhead failures and or what actually caused the one reported on here?

I had a total bulkhead failure on my front bulkhead this spring. Cause to the best of my observation was rust jacking. The angle iron was not severely rusted (was surface rust, heavier on the fron than the back) and the box beam was relatively clean of rust except for the very ends right behind the wheels. What was left of the Rolok bolts however were nothing but rust. The box beam had a painted or coated surface the angle iron and Rolok bolts did not. There was a gap between the angle iron and box beam, so I guess what folks call Jack Rust was the cause of the failure. You can call it anything you want but when you come right down to it, it was rust, and specifically rusting of the Rolok bolts, that caused the failure pure and simple. The failure occurred in Louisiana. Had some band aid fix done in LA and drove the coach to Maine. Took me all summer to complete the repair. I used a product called "One Step" (tannic acid) to treat the rust. Don't know why they call it one step as you have to apply two coats. But after the second application dries it leaves a treated paint-able surface. I finished the job with multiple applications of undercoating. I can assure you the Rolok bolts will be torqued once a year and there will be no rust on the bulkheads of this coach as long as we are the owners. It's not that the issue can't be fixed once the bulkhead fails but what a major pain in the touche it is to fix. When I inspected the rear bulkhead I found that some Rolok bolts had failed in the past but the issue had been addressed. Why they did not address the front bulkhead is a mystery to me.

I have several posts on the forum regarding this issue. My initial post was titled "Has this happened to anyone" if I remember correctly.

Roland

Re: Another view on torque testing bulkhead

Reply #19 – October 31, 2012, 12:58:35 pm

My point in questioning the in-lb/ft-lb thing is that while many of us may not be really technical people, we should be careful in posting something that might cause some do-it-yourselfer to try to pull 250 ft-lb on each of his bolts and think that they had all failed while he was actually pulling the threads or breaking them off.

Re: Another view on torque testing bulkhead

Reply #20 – October 31, 2012, 02:35:01 pm

Quote from: Roland Begin – October 31, 2012, 12:03:40 pm

I had a total bulkhead failure on my front bulkhead this spring. Cause to the best of my observation was rust jacking. The angle iron was not severely rusted (was surface rust, heavier on the fron than the back) and the box beam was relatively clean of rust except for the very ends right behind the wheels. What was left of the Rolok bolts however were nothing but rust. The box beam had a painted or coated surface the angle iron and Rolok bolts did not. There was a gap between the angle iron and box beam, so I guess what folks call Jack Rust was the cause of the failure. You can call it anything you want but when you come right down to it, it was rust, and specifically rusting of the Rolok bolts, that caused the failure pure and simple. The failure occurred in Louisiana. Had some band aid fix done in LA and drove the coach to Maine. Took me all summer to complete the repair. I used a product called "One Step" (tannic acid) to treat the rust. Don't know why they call it one step as you have to apply two coats. But after the second application dries it leaves a treated paint-able surface. I finished the job with multiple applications of undercoating. I can assure you the Rolok bolts will be torqued once a year and there will be no rust on the bulkheads of this coach as long as we are the owners. It's not that the issue can't be fixed once the bulkhead fails but what a major pain in the touche it is to fix. When I inspected the rear bulkhead I found that some Rolok bolts had failed in the past but the issue had been addressed. Why they did not address the front bulkhead is a mystery to me. I have several posts on the forum regarding this issue. My initial post was titled "Has this happened to anyone" if I remember correctly.

Roland

Roland,

After considering several solutions for replacing the bolts, I contacted several bolt suppliers and inquired about Roloks. After explaining the application they were being used for in our Foretravels, the suppliers recommended a different type of replacement bolt. Roloks are typically used in economical, mass production assembly where several steps can be saved with the Rolock making high quality rolled threads that are stronger than the threads formed by normal taps. While there are taps that do roll the threads, the Rolocks save a step here. A couple of other items: they are grade 5, not grade 8. There is NO mention of any rust/corrosion resistance ablility and in fact, they have NO coating. The PDF for their specs can be downloaded at: ENGINEERING SOLUTIONS: Rolok® Thread Forming Fasteners – EFC International

One of the replacement suggestions was the Tap-Flex fastener with the same grade 5 and thread rolling features but also with excellent corrosion resistance. They have excellent resistance to embrittlement failures required in critical curtain wall and dissimilar metal applications. See the manufacture's specs here: Tap-Flex They make 2 1/2" bolts that will reach through the angle iron, the bulkhead tin and both sides of the 1 1/2" square tubing with the recommended amount of thread left over. This is without putting a nut on the far end, just drilling and threading them in.

Stainless steel was another option and was the choice I made. I have been replacing my bulkhead bolts, a few at a time, first with temporary grade 8s for a trip and now with 3/8-16 316 stainless with 316 washers and nuts at the far end. I selected 316 (stronger than 18-8 stainless), the most corrosion resistant of all stainless bolts. They generate very little electrical current between the stainless and the steel angle iron/square tubing unless in constant contact with water over a long period of time. Just to be on the safe side, I have been installing two for every factory Rolok. Not much extra work and the minimum box amount was 50 so I will have a couple left over when done. (torque for 316 3/8-16 is 247 INCH lbs)

Without treating the angle iron, rust jacking can cause any bolt to fail so this must be done in addition to replacing bolts.

Pierce

Re: Another view on torque testing bulkhead

Reply #21 – October 31, 2012, 04:01:48 pm

Pierce. You are correct the Rolok bolts have absolutely no coating on them to prevent rusting through. The bolts on my coach were totally rusted through. I had thought of carrying some spare Rolok type bolts in case I experience failures when I perform a yearly torque test. But then I thought to myself that's shutting the barn door after the horses have run out. I will keep testing both bulkheads yearly HOWEVER I will also clean and reseal the both bulkhead areas yearly. I believe the correct approach is to PREVENT rust from getting a start instead of repairing the damage that it causes. FWIW

Rolandi

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