Electrolysis and aluminum sided trailer

[1010]

Is anybody familiar with damage done by electrolysis on an aluminum sided trailer? I have a 2002 Komfort TT that has 4 panels that need to be replaced. One panel has two holes in it. All the panels are below the floor, do I need to be concerned that the damage will creep up into the panels above the damaged panels. I have had a couple of quotes for replacing the panels (minimum) that have me thinking it may not be worth repairing, especially since we are looking at purchasing a new RV.

[nightriderrv]

There is water getting in somewhere in that area I have seen this before they start out as pin holes and get bigger if your looking to by new you can seal the holes with proflex sealant sold at most RV centers. I would find the source of the moisture too.

[1010]

Originally Posted by nightriderrv

There is water getting in somewhere in that area I have seen this before they start out as pin holes and get bigger if your looking to by new you can seal the holes with proflex sealant sold at most RV centers. I would find the source of the moisture too.

I have a pretty good idea where the water is getting in on 3 of the 4 lower panels, the 3 are all on the lower panels, the other might be leaking from the next panel. Of course the water could be coming from around the doors on the right side as well. I used silicone as a temporary fix. Unless we sell it soon, I will have to repair any suspect spots so no more water gets in, but that is a temporary fix too. My main concern now is the spread of this cancer to the upper panels or the floor as the moisture is already present below the floor. Thanks for the tip on the Proflex sealant, I will check it out. If I sell, I disclose all I know about what I am selling, good or bad. Thank you for responding.

[Francesca]

Electrolysis is a reaction caused by the contact of two dissimilar metals in the presence of water. Best prevention is the installation of a barrier (gaskets, e.g.) between the metals at time of construction. Why weather-exposed objects like RV's continue to be built without basic protection from this condition is beyond me!

In any case, given the difficulty of installing such barriers post-construction, your next best bet is the use of sealants in hopes of eliminating water from the equation.

[1010]

Originally Posted by Francesca

Electrolysis is a reaction caused by the contact of two dissimilar metals in the presence of water. Best prevention is the installation of a barrier (gaskets, e.g.) between the metals at time of construction. Why weather-exposed objects like RV's continue to be built without basic protection from this condition is beyond me!

In any case, given the difficulty of installing such barriers post-construction, your next best bet is the use of sealants in hopes of eliminating water from the equation.

Thank you for explaining electrolysis and how to prevent it. It does seem like it would be fairly easy to wrap a barrier or place gaskets where needed during construction of an RV, but build them fast build them cheap is the way things are now. Knowing what I know now I would gladly pay extra for that barrier. Nothing is full proof with an RV, but like you said, this is pretty basic considering RVs are all most always exposed to the weather. If I do decide to repair the trailer I will make sure that putting a barrier of some sort is placed where needed.
I found another spot forming above the floor on the slide, no moisture on the interior or on the carpet. This one appeared over night. It has not been raining or even damp here for quite awhile. This has turned into a nightmare, so I hope who ever reads this post does more then just look at the seals on their RV.

[nightriderrv]

It's the production and $$$$ thing how many they can put out the door and for the lowest cost to build. I have seen and repaired units from the 80's and they are built way better than some of these new ones.

[1010]

Originally Posted by nightriderrv

It's the production and $$$$ thing how many they can put out the door and for the lowest cost to build. I have seen and repaired units from the 80's and they are built way better than some of these new ones.

nightridrrv you are right and the pattern continues on and on. I am no expert on the construction of TTs, but I have not seen anything out there that seems to be built any better, the units have less storage space on the inside & from the outside, (seems to be an industry standard practice), less capacity on holding tanks, smaller micro waves and the list goes on.

[Tony Lee]

Problem often occurs with aluminium cladding fixed to steel framework and even with best-practice installation is pretty hard to eliminate completely because it is almost inevitable that somewhere there will be points where different metals are in contact and there is always moisture in the air that will condense on these surfaces.

For yours to get to the point of perforating sheets in a relatively short time points to lack of basic care in installing barrier tapes, use of correct fasteners, or waterproofing.

Another factor that can hasten corrosion is running large DC loads where the return leg of the DC current runs through the chassis. If the layout is right (or wrong), this current can flow through the skin, or through other components such as copper/brass radiators and speed up the corrosion process by a large factor.
Currents don't have to be all that large to cause the effect and even clearance lighting using the skin as a return path can speed up the process and it will show up as corrosion where there is a screw or rivet to conduct the current from the skin to the metal framework.

Even all-aluminium construction can suffer if the wrong aluminium fasteners are used.

[nightriderrv]

Agree X5

[Francesca]

Originally Posted by Tony Lee

Another factor that can hasten corrosion is running large DC loads where the return leg of the DC current runs through the chassis. If the layout is right (or wrong), this current can flow through the skin, or through other components such as copper/brass radiators and speed up the corrosion process by a large factor.
Currents don't have to be all that large to cause the effect and even clearance lighting using the skin as a return path can speed up the process and it will show up as corrosion where there is a screw or rivet to conduct the current from the skin to the metal framework.

Is there any way to install some sort of "sacrificial anode" on a rig that would direct such stray current to a designated dissolving object?

Or do I suffer from a complete misunderstanding of what a "sacrificial anode" is???

[1010]

Originally Posted by Tony Lee

Problem often occurs with aluminium cladding fixed to steel framework and even with best-practice installation is pretty hard to eliminate completely because it is almost inevitable that somewhere there will be points where different metals are in contact and there is always moisture in the air that will condense on these surfaces.

For yours to get to the point of perforating sheets in a relatively short time points to lack of basic care in installing barrier tapes, use of correct fasteners, or waterproofing.

Another factor that can hasten corrosion is running large DC loads where the return leg of the DC current runs through the chassis. If the layout is right (or wrong), this current can flow through the skin, or through other components such as copper/brass radiators and speed up the corrosion process by a large factor.
Currents don't have to be all that large to cause the effect and even clearance lighting using the skin as a return path can speed up the process and it will show up as corrosion where there is a screw or rivet to conduct the current from the skin to the metal framework.

Even all-aluminium construction can suffer if the wrong aluminium fasteners are used.

My trailer is wood construction with aluminum siding, where this all started is aluminum siding backed by wood (under the floor) and that is where the two holes appeared. It appears that the damage is accelerating and moving upward, the weird thing is where I first noticed the "dimples", that has remained pretty much the same. All the seals on my roof appear to be solid, no tears or holes either, still the way the damage is progressing on both sides (so far not on the front or rear) makes me think the leak(s) are higher then I thought, including the roof. The panel where this first appeared does have a ground wire screwed through the aluminum and into wood. Is this the "return path" you are talking about? Is the skin of the trailer purposefully being used as a return path? I have not talked to any one that has seen the kind of damage that is happening to our trailer and most (except those familiar with RV repairs) have not heard of or seen damage caused by electrolysis.
Thanks for your reply and insight into a very serious problem.

[1010]

Originally Posted by Francesca

Is there any way to install some sort of "sacrificial anode" on a rig that would direct such stray current to a designated dissolving object?

Or do I suffer from a complete misunderstanding of what a "sacrificial anode" is???

I am wondering the same thing?

[Tony Lee]

Is there any way to install some sort of "sacrificial anode" on a rig that would direct such stray current to a designated dissolving object?

They certainly do on boats, and there are electrical systems that provide similar protection by passing electric currents through the frame and components. Used generally to protect steel structures such as pipelines, reinforced concrete and machinery such as bottle - washing machines. There is a version available to stop vehicles rusting, but there are some who put it in the category of snake-oil


Often, cladding panels are deliberately grounded so they can't become alive from faults in the mains wiring, Some codes make it mandatory,

In your case it is hard to see how one isolated connection could cause that much corrosion in several panels, particularly when you say there are no dissimilar metals involved in the near vicinity.

So, no dissimilar metals, maybe no electric currents, so does that leave only some sort of chemical attack? Also strange because aluminium quickly forms a pretty hard oxide coating that resists attack in most day to day situations. One thing that will cause big damage is caustic soda (sodium hydroxide) and presumably other alkalis as well. Some areas use ???? for dust suppression on gravel roads and that is very corrosive, but how that could be a factor in this case is hard to see. Timber framework has been around forever so unless they have started to use one of those treated timbers (rotproof, termite proof) and somehow those chemicals in the presence of moisture are corrosive to aluminium. If it was some sort of copper compound, that might react.

As you can see, I'm no expert so just throwing stuff in the ring in case someone else can run with it.

[1010]

Tony Lee,
You are very knowledgeable about this topic and I really appreciate your insight into my problem. I found another spot a couple of days ago, this one is located at the top of the second from the bottom panel and is the highest one yet. Maybe the aluminum has come into contact with metal screws or some other type of metal fasteners used to attach the wood framing. The only place where there is concentrated damage is the lower right panel, which has developed a couple of holes. A few of the spots have appeared below suspect seal leaks, but the last few are not near any seals. I am aware that water can travel a long ways before it appears, maybe this is what is happening. When you use the word "moisture" is that synonymous with "water?" Maybe this can be fixed with a "moisture" issue, but I doubt a "water" issue would be repairable at the rate the dimples are appearing. Is electrolysis damage limited to area near the area where the dissimilar metals meet, or is the damage able to "spread" to other areas and just pop out in distant panels? The ideas you are throwing into the ring are certainly thought provoking. I doubt the wood used in building a trailer would be treated lumber, but maybe in 2002 there was no health concerns, I think this is worth pursuing. Komfort was a Thor line in 2002, but Komfort is no longer carried by Thor. When I get home I am going to contact Thor and see if I can get any answers on this issue. I am kind of surprised that I seem to be the only one on this forum that has had this problem.