I Just Had My Tanks Anodized (pics)

[onca2002]

I had a couple of tanks handed down to me that were pretty beat up. I looked at having them repainted or just leaving them stripped down to the bare aluminum. Then I remembered that my wife worked for a company that anodizes aluminum. Spoke to the owner and to a tech guy at Catalina and came up with a plan.

First I stripped them using a paint stripper I bought at Home Depot. Took about 1 hour to strip them both. I lightly sanded areas that had corrosion built up...which covered about 10% of each tanks surface. I used 600 grit sandpaper and sanded until smooth.

I had the tanks empied and valves removed...plugged the holes with plastic plugs from LDS.

I dropped the tanks off at the anodizers, and decided to go with recommended black. Because of the previous corrosion on exterior of tank, it left "scarring" or marks on the surface which would be visible after the process was completed. I could have sanded the marks down so you could no longer see them, but I wasn't interested in reducing the thickness of my tanks walls. Rather have tanks with a few small marks than a tank that fails a Hydro.

Anyway, I just got my tanks back, and I'm pretty happy with them. With the new finish you can scratch a key on the tank and it will not leave a mark. It's very hard.

All it cost me was a bottle of paint stripper ($7.00) and a $25.00 donation to a charity the company is raising money for. Pretty Sweet Deal!!!

Attached some pics for those who are interested. I wasn't sure how this project would turn out, but I'm happy and learned a lot in the process. Hope you enjoy.

 

[sporket]

They look very nice. Well done.

 

[roakey]

Any LDS that has half a clue is going to ask you get them hydroed before they fill them, that's SOP for any newly "painted" cylinder -- they have no way of knowing if what you had done had any kind of heat treatment involved.

Roak

Ps. And yes, I realize that at least the blue one was hydroed only a year ago...

 

[Pug211]

They look great.

Does the anodizing change any of the characteristics for the hydro on them?

 

[Bound]

They turned out great.

Any LDS that has half a clue is going to ask you get them hydroed before they fill them, that's SOP for any newly "painted" cylinder -- they have no way of knowing if what you had done had any kind of heat treatment involved.

Roak

Ps. And yes, I realize that at least the blue one was hydroed only a year ago...

You must of had the dad that pointed out that one B on the report card and missed all the A's.

 

[onca2002]

No, anodizing does not affect the integrity of the tank. The process only heats the tanks to 140 degrees. Acording to Catalina, anything below 320 degrees is safe.

And someone will probably want it re-hydro'd. They are gonna have fun stamping it...the coating is super hard. LOL They'll be able to do it, but it's not going to be easy.

 

[pescador775]

Some types of anodizing are very hard, indeed. I tried to remove a small patch of anodized surface from aluminum using coarse grit carborundum cloth, and after 15 minutes of sweat labor had not accomplished a thing. I tried another grit and another 15 minute workout resulted in a small amount of anodizing removed from a single sharp edge on the aluminum but the rest showed no sign of abrasion. Other types of anodizing can be scratched with a dull knife.

 

[onca2002]

Yes, there are varying levels of hardness, this company has many military contracts and the finish is very hard. I did get them to pull them out of the soloution early, so they are not indestructable...simply beacause I knew they would need to be hydro'd and at it's hardest, there would be no way to stamp the tank. The problem would arise if the tank were to hard and someone was wailing on in with a stamp and a hammer that the tank could chip, and you'd lose a chunk of your tank.

 

[Jimmer]

Let us know when you do get them hydro'd. Hard and brittle often go hand in hand, and I would be interested in know if that would be reflected in the hydro test results.

 

[Luis H]

Hard anodized aluminum is a surface conversion that creates a very hard uniform aluminum oxide layer. It is a great finish. It is a very common finish used in marine hardware such as sailboat masts. As most finish it is not very thick, but it is much thicker and much more uniform (and smooth) than the naturally occurring aluminum oxide.

The only concern is as mentioned above is that it is more brittle than the parent metal and it will not flex as easily. The worst thing is that you may get some crazing spider web type of minutes surface cracks on the finish. This should be small enough that should not cause structural problems, but you do need to keep an eye on it for corrosion.

If this crazing occurs, it will most likely happen during hydro, when the cylinder is expanded to its maximum. Hopefully it will not happen at all.

Let us know how they do after the hydro.

Good luck.