Protecting the inside of tube steel on a trailer?

[jeepxj2007]

Hello all! I am in the process of finishing up a nice boat trailer I built from scratch using tube steel. For the main structure I used 3x2x.125 rectangle tube, and for the tongue I used 3x3x.188. A 16' Polar Kraft Dakota deep v will sit on it. It is a basic aluminum boat, pretty light actually and the trailer is built pretty heavy duty for the wet weight of the boat. I designed and built the trailer so that all of the tubing with the exception of the tongue is welded airtight. For running wires I was going to attach them to the inside of the tube and where it crosses each cross member or has to cross the trailer the tube has been sleeved and seal welded both sides to make a hole that wont allow moisture inside. This boat will NEVER see salt water nor will the trailer. I built it to last but again I don't plan on owning it forever because I know down the road living in Michigan I will want a bigger "Big Water" boat. My question is what should be done about the inside of the tube steel? I received a quote for 400 for hot dip galvanizing the trailer, but it will need to be hauled 3 hrs one way and back and with work it sucks trying to make time and I already purchased a good quality epoxy primer and black paint to paint it. Hot dipping it would require vents drilled in it which wouldn't be a big deal because it will be galvanized. My second option was to weld in a 3/8" or 1/2" NPT coupling into the bottom of each sealed section and one at the top and add a thick viscosity oil into the inside and seal it back up with a plug in a unseen area. I don't see how painting the inside of tube steel will be possible, especially being all new steel and coming with its millscale and oil finish on it. I work as a industrial pipefitter and haven't seen the inside of any tube structure painted, but nothing is submerged in water either. Is it something to worry about, or just run it as is? Any suggestions would be appreciated! Thank-you!

 

[roscoe]

Re: Protecting the inside of tube steel on a trailer?

First off, welcome to iboats.

You are likely to get all kinds of opinions on this

Well, it would probably last 40 years as is, if you get a good protective coat on the outside.

Galvanizing the outside would keep it looking nice for a long long time.

A decent prep and paint with quality paints would last many years as well, but would need touch-ups if you start getting chips and you want to keep it looking new.




The parts that rust the most in our climate, are the bolt-ons, fenders, hangers, bunk brackets, axles, and cheap nuts and bolts. But even these parts seem to last 30-50 years.


Since you already have "big water fever", prep, prime, and paint the exterior.

 

[Grandad]

Re: Protecting the inside of tube steel on a trailer?

Welcome jeep. I kinda like your idea of totally sealing the tubes and installing pipe plugs and heavy oil. I think though that if you run wiring inside the tubing that the wire/cable entry points will be difficult to totally seal. There's bound to be some seepage of oil at these points. If you were able to run the wires in a suitable protected fashion (eg sealtite flex conduit) that was fastened to the outside of the tubing, you could probably seal the tubing well enough that you wouldn't be polluting every launch ramp. Also, running the wires in a hot oil bath will require conductor insulation that won't be destroyed by the oil.

So, ya, I think it could be done, but maybe not worth the extra aggravation. Besides, when twofootitis starts in a couple of years, you'll be able to trade it in without losing that additional investment. I'm sure that my trailer tubes are rusting from the inside, but that's the cost of trailer ownership. I've actually added some sizable drainage holes and I make sure they're draining well when I pull out from a ramp. - Grandad

 

[Watermann]

Re: Protecting the inside of tube steel on a trailer?

Sounds like you have some serious metal working skills and the equipment to back them up.

The only worry I would have is that the tubes aren't completely air tight. Water will always find a way to ruin something no matter what it's made of given enough time and it would find it's way inside sooner or later. I think you could put a fitting on the tubes you can charge with air pressure or drawn down with vacuum to see if they leak down? Would also be a good port to blow in a charge of oil.

I launched my boat in some high water up on the ramp this season and on the way home I felt this small almost unnoticeable vibration in my truck. Turned out to be a quart of water inside my aluminum drive shaft. Never heard of that happening let alone see it happen.

It would be nice to see a few pics of your creation!

 

[smokeonthewater]

Re: Protecting the inside of tube steel on a trailer?

First thought is that your trailer is possibly gonna float... not good....... Next if the inside of the tubes do not have a constant supply of oxygen they can only rust until the small amount of oxygen trapped inside is depleted..... once it's gone with just a little surface rust then no more rust can occur until the tube gets a hole in it from the outside. (as mentioned above a pressure test will confirm the seal)

Don't bother with oil and pipe plugs.... Rust, iron oxide, CAN'T occur unless you bring iron and oxygen together.

Last thought.... this trailer will be on it's 4th or 5th owner before rust becomes an issue even if you leave the inside raw and open

 

[Frank Acampora]

Re: Protecting the inside of tube steel on a trailer?



Here is a trailer with completely open frame and tongue. water drains from it as I pull out and it dries from wind on the road. I bought this trailer in 1967!. Yeah, it has some internal rust, but not enough to affect it structurally. Not bad for a 46 year old trailer!

First photo shows the "new " larger trailer.

There were three reasons I dismantled it, none related to internal rust:
1. I am going to prime and paint it
2. It was always overloaded. A number of years back with non-boat use, I bent the axle. I straightened it but the wheels took on a permanent camber at the point where the spindles were welded.
3 .I got a bigger trailer for the boat and upgraded from those itty-bitty 8's to 12 inch tires.

You already have overkill. Don't worry, simply enjoy using it.

 

[bigdee]

Re: Protecting the inside of tube steel on a trailer?

View attachment 209037View attachment 209038View attachment 209039View attachment 209040

Here is a trailer with completely open frame and tongue. water drains from it as I pull out and it dries from wind on the road. I bought this trailer in 1967!. Yeah, it has some internal rust, but not enough to affect it structurally. Not bad for a 46 year old trailer!


You already have overkill. Don't worry, simply enjoy using it.

I agree with Frank. No need to re-invent the wheel.....Drill some drain holes and go boating!

 

[rbh]

Re: Protecting the inside of tube steel on a trailer?

Yup, let the frame breath.
Between the lake water penetrating into the tubing and condensation build up, just let it breath.

 

[colbyt]

Re: Protecting the inside of tube steel on a trailer?

While reworking my old trailer (30+ years) I was amazed to discover that the inside of the tube beams were painted to match the factory paint job. I've been meaning to look up the process but haven't. I would be willing to place a small wager that none of them leave a modern factory like that today.

Honestly I don't think it will ever be a problem unless you dunk in salt water.

 

[TJS]

Re: Protecting the inside of tube steel on a trailer?

If you are certified Pipe fitter I doubt your welds will have any voids in them and not leak. In actuality the trailer is now a big pressure vessell.

 

[jeepxj2007]

Re: Protecting the inside of tube steel on a trailer?

Thank-you for all the replies and suggestions! I will get some pics on here real shorty showing the trailer, and I will give a little disclaimer that it is pretty overkill for the boat that is on it...but I guess I'd rather build it once than multiple times. The wiring wont actually go inside the tube, I'd like to find a way to mount some either flexible corrugated conduit like you see under the hood on your wiring harness or go with galvanized emt conduit on the inside of the frame rails where you wouldn't see it, if I were to enclose it and give it a oil bath they would never contact the oil. any spots were I need to jump through the frame have been drilled with a hole-saw through both sides, then a piece of e.r.w. tube was put in and welded on both sides then ground smooth to make a sealed penetration through the main tube. Judging by all the advice I may just do the drain holes like everyone said. I wish I would of realized this before taking the time of sealing it all up...but hey you win some and you lose some....:laugh: The pics will be up in just a few minutes, I used ultimate bunk boards for the bunk boards and I have yet to put the fenders on and build the front keel/bow roller bracket. Once again thank-you for all the advice, I really appreciate it!

 

[jeepxj2007]

Re: Protecting the inside of tube steel on a trailer?

 

[colbyt]

Re: Protecting the inside of tube steel on a trailer?

I wish I shared your welding skills. Nice looking trailer.

 

[glenn property of pam]

Re: Protecting the inside of tube steel on a trailer?

if you really wanted to go over kill then a wax injection treatment would work wonders
Corrosion Prevention | Waxoyl USA its a bit like Cosmoline there are other brands like por 15. I use it on old British sports cars to get in the places that like to rust from behind.

 

[Watermann]

Re: Protecting the inside of tube steel on a trailer?

That is a sweet looking well built trailer alright. Great job!

 

[smokeonthewater]

Re: Protecting the inside of tube steel on a trailer?

3/8" or 1/2" steel brake/fuel line tacked along the frame rail makes a great conduit

 

[bruceb58]

Re: Protecting the inside of tube steel on a trailer?

My brother has a closed tube painted trailer for his 26' Formula. All the cross members are rusting through. He is looking for a new trailer.

C channel is the only way I would have a trailer. Box tube only if the ends are left completely opened and then galvanized..

 

[Bamaman1]

Re: Protecting the inside of tube steel on a trailer?

Just paint your trailer well, and go and enjoy it. If it ever rusts out as long as you have it, you can just build another out of channel steel.

As long as it's not going into salt water, you'll be okay.

The vast majority of new trailers are square steel tubing. All the big trailer manufacturers have big tubing benders to make a "pretty trailer" and they're welded in jigs. Unfortunately not all the steel tubing is of the highest quality and many trailer builders.

I have a tube trailer on my new tritoon boat. It should still last many years as my boat's sitting in a boathouse.