I have succesfully treated and painted my own cars in years past, but this is a whole lot different. Let's take a welded mild steel "box" with a long untreated bare-wall metal internal passage, unreachable by brushes, grinders etc, and assume it certainly has internal scales and likely a debris-covered inner surface (some dark scales from oxy acetylene welding with lots of heat, and some mig welding scars inside) that I want to chemically clean and hopefully protect somewhat so I can use it safely as an intake air passage for the engine air. I am pretty sure it will have to involve soaking it in a chemical bath to hopefully strip the inside surfaces of the heated scale due to the outside welding, and I also understand that any rust reducing effforts will also be from a long bath too. IT IS NOT RUSTY AT THE MOMENT, but probably will be fairly quickly after putting it in use. Since it is made of mostly .093 and a little .120 thickness, and is a lightly stressed unit, I believe it can stand quite a bit of material removal that a thin sheetmetal structure couldnt. OK. WHAT DO I DO NEXT? If you have a favorite and effective cleaning method, or scale-removal method, and/or an effective prep bath that is simple for a non-expert who doesn't know where to buy uncommon items, please also mention where I can actually get the stuff without needing special connections inside the industry. If possible, I would like to dip it and flush it, or FILL IT with liquid, and then magically hope it will have a cleaned and protected interior. Is it too much to hope for? Even if I cant protect it, can I strip the flakes and possible scale to make it safe to use as an air passage? HELP! Thank You. WHY BE ORDINARY ?
Put a hand full of deck screws and some hot water/detergent in it. cover the openings and shake shake shake. The screws will scour and scratch the metal and the water/soap will remove oils. Repeat if needed. Prime and paint with brush if necessary.
I would use a motorcycle gas tank coating kit to keep it from rusting. POR-15 used to make one that I've heard nothing but good things about. https://www.por15.com/POR-15-Motorcycle-Fuel-Tank-Repair-Kit Similar results for Caswell, who also make a moto tank coating. https://www.caswellplating.com/epoxy-gas-tank-sealer.html Good luck.
There MUST be some sort of liquid treatment or acid or such that I could slosh around inside the chamber that would treat the tarnished bare metal surfaces to slow down the rust that will most certainly start soon. I thought people here had some favorites for preserving or treating. I just wanted to know where to buy them. I do not want to use a fuel tank liner that can peel later. I am just trying to find a way to soak and rinse, and slow the unevitable rust. The part is too long to tumble it with abrasive inside, and too difficult to get long brushes to reach inside.BUT I can probably plug an end and fill the passage with liquid. Favorite strong weld-scale-stripping chemicals? and sources? some other thread mentioned pool chemicals??? Do they do something that would help here? dumb questions possibly, but I'm not sure what to try out.. I am contemplating using the strong por metal-etch, but might there be something more apropriate? thanks. P.S. I just spotted a gallon of por rust remover, a new product I suppose, at a local Menards hardware store. I suppose I will try that unless someone here has a better suggestion of a better product. I hope it helps delay any future rust formation on the unpainted surface. WHY BE ORDINARY ?
You likely have discolored metal from mig and gas welding heat which of itself shouldn't be a problem. How about a design requiring less welding? I've never heard of acids that remove scale. A product like PHIX, ( auto parts store ) which contains zinc phosphate, is a good coating for steel while in storage and after following additional procedures is a good foundation for primer. Phosphoric acid would most likely be stronger but the surface would be prone to flash rust if not rinsed, dried and coated immediately. Fuel vapor will help rustproof the passage or fog the inside with WD-40
I know this response is late but many projects stall or someone else can benefit in the future. I used a 3000 PSI pressure washer with a spin nozzle/rotating nozzle like those for cleaning drain-lines to run through a boxed frame. I did this on a Henry J and pulled out all sorts acorns and nut shells that chipmunks or mice had stored. I also did it on the wife's 57 wagon that had been owned by a surf fisherman. I got tons of sand out of that one.
The Jalopy Journal
