rustproofing inside trailer frame?

**dakotachaos** · 04-19-2010, 06:50 PM

hey guys, im a very experienced welder and am comfortable with my abilities, but am not sure if im going about this in the right way. im planning a trailer build thats going to be as perfect as possible with a very clean look. its just going to be a 6x12, but i plan on using tubing for the perimeter frame. with 45's at each corner, i hope to be able to seal out any water, salt and such. all i want is to be able to rust proof the inside of the frame, but am not sure how to do it. i had a thought that rust needs oxygen to form right? so if i weld a threaded bung and added a guage, and added a slight vaccuum to the inside of the frame, then not only would i beable to tell if theres any pinhomes in the welds, but it would also rid the insides of oxygen which in turn would hopefully keep the insides from rusting out?

im very set on using rectangular steel tubing for the main frame, but i dont want them to fill with water and such and rust out from the inside out. i should add that i live in minnesota, so rust is everywhere on everything that drives on these roads do too higbh salt usage.

any suggestions are welcome!

**urch55** · 04-19-2010, 08:39 PM

Why not purge the inside with shielding gas that would allow you to make sure all welds are water tight and leave the innards oxygen free then plug it off. When I have to cut an axle it's like brand new inside because it's air tight. Just a thought.

**Rocky D** · 04-19-2010, 10:00 PM

Why not just buy galvanized tubing? That's what I do. Or you could have it galvanized after you build it.

**dakotachaos** · 04-19-2010, 10:45 PM

i thought about galvanizing, but i dont want to spend a couple hundred bucks doing the whole thing, and welding galvanized is kind of a pain.

i never thought about using shielding gas, thats a great idea, other then i dont have any. i wonder if i could use helium? my job rents helium tanks so maybe that would work other then its flamable properties.

**Roger** · 04-20-2010, 07:13 AM

100% Helium is inert having no flammable properties. Helium for filling balloons is He02 mix so children can breath it and not pass out. Helium is hard gas to contain because it has smallest molecule.

For aircraft tube frames they squirt a little tube oil inside frame to reduce rust because it is hard to make them with no pin holes.

**urch55** · 04-20-2010, 08:17 AM

Originally Posted by dakotachaos

i never thought about using shielding gas, that's a great idea, other then i don't have any. i wonder if i could use helium? my job rents helium tanks so maybe that would work other then its flammable properties.

Rent a small bottle for the time it takes you do fabricate the main frame. It's probably cheaper than you would think, then barrow a regulator with hose an you have it. C02 might be the cheapest gas I don't know. I use 75/25 with my mig.

What welding process are you planning on using.?

**Big_Eddy** · 04-20-2010, 01:05 PM

I don't think that you're going to have any success sealing it air tight and trying to keep it that way with a purge in it. I'd suggest instead leaving a small opening at either end of each tube, then spraying in a rust proofing coating once the frame is complete. By having an opening at the end, you direct the spray down each tube. Then fill the hole with a self tapping screw or similar.

I think a light coating of rust proofing oil would be much more effective than a purge, and more likely to stick around over time.

If you are planning a purge - you need two openings at opposite ends - 1 to add the purge gas, and another to exit the displaced air.

**usmcpop** · 04-20-2010, 01:43 PM

Stuff in some Camphor blocks before you weld it all shut.

**urch55** · 04-20-2010, 02:08 PM

What I was contending is after all the welds were done and air tight, purge the inside of the tubing then screw in the plugs one at each end at the furthest point. Not welding it as it is being purged. I have cut axles and drive shafts being many years old and they were like brand new inside. And I doubt if they were purged. Anyway just my thoughts, I just wanted to make myself clear.

**dakotachaos** · 04-20-2010, 10:00 PM

urch, thats what i planned on doing. once i sealed it all off, using a femal air connector at one side for the gas inlet, and a valve on the other end. i have a 140 mig. i will be using fluxcore, because thats what i have as of right now.

usmc- ive never heard of camphor blocks, care to ellaborate?

bigeddy- i too agree that it will be hard to make it airtight, but with 12" long frame rails, im unsure it would be able to be squirted all the way down.

**dakotachaos** · 04-20-2010, 10:48 PM

I did a little research on those camphor blocks and that actually sounds promising, but how long would they last do you think?

**usmcpop** · 04-21-2010, 08:18 AM

If the frame is well sealed, I'd imagine camphor or other vapor-phase corrosion inhibitors would last longer than we will.

**urch55** · 04-21-2010, 09:11 AM

Dako.. Which ever way you decide go, at least you have some options. I am sure your trailer project will turn out great. You will have to show us the finished trailer. When I hear of Camphor wood I think of Vicks Vapor Rub, if you go that route at least your trailer frame won't get sore in the joints.