Fill And Drain Welded Tube Frame

[Dave1968]

Using the materials available these days, what is best to use for protecting a welded steel tube fuselage frame from interior corrosion?
Any information, tips and references to procedure descriptions will be appreciated! (I've searched posts here and didn't find anything)
Thanks, Dave

[CraigCantwell]

I've done the boiled linseed oil before. I set the fuselage up on a rotisserie and used a homemade fill system. I took a piece of 2" pvc and added a hose barb fitting to a cap and glued it on. Rigged up some clear tubing to the fill port and added a couple of quarts slowly. Every so often as I was working on other stuff, I'd add more BLO. Once it wouldn't take any more, I ended up with the engine mount area on the hangar floor and the tail pulled up high in the hanger. Kept adding BLO til I had about 3 1/2 gallons in the tubing. Pulled the filler off and install the plug and put it back on the rotisserie and rolled it a 1/4 turn every day or so, until it was back upright. Reversed the setup and drained every bit of the BLO out that I could and then installed the plug for the last time.

One thing to understand with BLO and rags....It and and will self combust under the right conditions. Anything that has BLO on it and is flammable, needs to go out of the hangar as soon as you are done with it and home in a metal can to stay outside and dry up until trash day a week or two later. It has to be completely dry before you put it in the trash or you run the risk of creating a trash truck flambe..... The used BLO can be dried out by pouring it up in buckets of cat litter or oil sorb and allowed to completely dry before going into the trash. If you local government has household hazmat pickup or drop off capability, then that's way faster.

[Dave1968]

Thanks for the reply Craig,
There are other choices for the fill these days besides BLO. I don't know enough about what they are and asking around so far hasn't been successful.
Thanks for the description of how you did it with BLO. It's got some safety complications I hope to avoid if I can find an effective alternative.

One more thing I need to learn is why my effort to set an email notification of your reply did not work! :-(

[Dana]

I used linseed oil in the new landing gear I built for my Starduster. You'll find every pinhole leak in the welds... :eek:

I believe ACS sells some sort of oil specifically intended for sealing tubes. Possibly a Stits product?

[CraigCantwell]

Not much different than dealing with any oily rags around the shop safety wise, other than a slightly higher probability of combustion.
If you can find it, Poly-Fiber has Tube Seal, which is essentially MIL. SPEC. L-21260 preservation oil and it will do the same thing.

[Dave1968]

Thanks Dana, ACS is one of the places I have sent inquiries... No response so far unless you count crickets! ;-)

[Dave1968]

Thanks Craig. I will check on that, but if the Poly-Fiber product is capable of spontaneous combustion as well then they may be not much different.
OBTW, some time ago I priced purified Linseed Oil at WalMart for $75/gallon. ACS does not sell Linseed Oil, at least that I could find and that was an early clue...

[CraigCantwell]

You don't want purified linseed oil, but rather, boiled linseed oil. BLO should be available at your local paint store for about $25 a gallon, or any decent woodworking place. Any oil type product can spontaneously combust with the correct conditions. BLO happens to be pretty easy to have happen. Used rags with motor oil will do the same thing in a garage. Just need some heat and no air circulation and it can happen. Oily rags from any source should be allowed to dry with decent ventilation and outside the garage in a metal can.

Worth the 5 minutes of your time to watch. Ryan nearly lost his place to not being cognizant of the the possibility. I think he would be fine with me posting a link here, especially if it opens the eyes of even one person.

https://www.youtube.com/watch?v=v0CPhmplHek

[Dave1968]

Hello Craig, and thanks for pointing out the nomenclature. I have never been around linseed oil in any form except as a very young lad when I "helped" my father treat a new wood deck on a flatbed trailer he had built. It was many years ago, as I am an old fellow now. I got motivated to research the subject and there are several forms and I don't know what variant my father used but I still recall that he boiled it and firmly admonished me about the dangers of the material.

Also, thanks for the video link. I have all metal cans with good lids in my shop. Thank you and everyone for the posts.

[Dave1968]

So, I'm still looking into what other materials are available.
ACS does offer a product called Nycote 7-11. It's offered specifically to include fill and drain use, but it's pricey, has a limited shelf life and storage conditions are restricted.
Lear Chemical (ACF-50) has responded that ACF-50 is a fill and drain option. This seems sensible but I have never heard of this. Has anyone used ACF-50 for fill and drain or seen any literature regarding that use?
I hope I didn't misread, but the Poly-Fiber product mentioned turned out to have a substantial ingredient of linseed oil.
I haven't found any Stits product...
Thanks everyone!

[Dana]

I hope I didn't misread, but the Poly-Fiber product mentioned turned out to have a substantial ingredient of linseed oil.
I haven't found any Stits product...
Thanks everyone!

Stits and Poly-Fiber are the same thing. The company Ray Stits founded eventually became Poly-Fiber, but people still call it Stits.

[John Caulkins]

For what it's worth (FWIW is the Millennial's way of saying this I think), when I worked at the airlines, we would corrosion proof the inside of the fuselages from the "waterline" on down using LPS3. It will burn, but is much less flammable than BLO or other petroleum products. Consider that metals there ranged from structural aluminum castings to aluminum sheet with high strength steel fasteners to various types of steel structure. I believe the correct way to express it would be to say that it "sets up" as opposed to drying, but maybe they are the same thing. Anyway, it always performed exceptionally well when you consider the amount of moisture that area encounters on each flight due to pressurization and respiratory moisture. Also, it was very easy to use. I have been building a GP-4 (Project currently for sale) where I have used it inside the 4130 engine mount frame, the 4130 push/pull rods (ailerons), and the steel landing gear shock strut and trunnion tubes (MLG is not Oleo - uses large spring). I highly recommend it.

[Dave1968]

Hello John! FWIW, you are correct about the Millennials. I have 3 of them. ;-)
Thank you very much for the information about LPS3. I will look at that and probably use that or ACF-50. I have just received a very affirmative response from Lear Chemical that ACF-50 is appropriate.

Thanks again!
Dave