eweingarden
Contributor
Someone gave me an AL 80 (manufactured in 1996) which needs to have a hydro. There is a little bit of rust at the neck/valve junction. Anyone know if the presence of rust makes it unuseable? Thanks.
Rust on Tank Neck
- Thread starter eweingarden
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Aluminum oxidizes, not rusts, and it's not a disqualifying factor per se. But get it hydro'd and inspected. They will tell you if it's useable or not--that's why you pay them. The $40-some bucks you're going to spend is worth it, even if it gets condemned.
OP
eweingarden
Contributor
Thanks
halocline
Contributor
Well, I wouldn't say its 'worth it' if the tank gets condemned, but unfortunately a hydro test is the only way you can find out if it's dive-worthy. So you have little choice.
As mentioned, aluminum does not rust, and it's likely that whatever valve was on there was brass/chrome, which also does not rust. So if what you're looking it is actually rust, I would want to find out how it got there. AL oxidation is white, hard to confuse with rust.
One thing you could do before bringing it in for testing is to look inside with a light just to get an idea of what it looks like. You need a light on a wand or string; actually a string of small Christmas lights will do the trick. If the inside looks like relatively clean metal to you, it's probably a good bet to get tested.
OP
eweingarden
Contributor
Halocline - thanks for the suggestions
I just kinda meant $40 bucks and knowing it's safe, versus trying to guess. But yeah, I understand getting pissed when you get your cylinder back with a hole drilled in it and then you have to pay for it.
OP
eweingarden
Contributor
I dropped it off for hydro today. I'll find out in 3 weeks.
Rred
Contributor
Odd that there would be rust, since most (all?) valves would be chromed bronze, or stainless, or other metals that don't normally rust. And of course the tank simply can't rust. So whatever the material is, it didn't come from the tank.
I would expect the tank to pass hydro unless there was pitting, etc. inside. Tanks are designed for 10,000 fill cycles per DOT spec, and it is hard for a recreational tank to be used that often.(G)
When you get it back, either you or the shop that first fills it, can apply a bit of "FDA approved food safe" lubricant in the threads before putting the valve in and filling it. (One that is Nitrox safe if that's a potential use.) That will ensure against any galvanic corrosion and galling in the threads, regardless of what caused the "rust" you've seen.
I would expect the tank to pass hydro unless there was pitting, etc. inside. Tanks are designed for 10,000 fill cycles per DOT spec, and it is hard for a recreational tank to be used that often.(G)
When you get it back, either you or the shop that first fills it, can apply a bit of "FDA approved food safe" lubricant in the threads before putting the valve in and filling it. (One that is Nitrox safe if that's a potential use.) That will ensure against any galvanic corrosion and galling in the threads, regardless of what caused the "rust" you've seen.
OP
eweingarden
Contributor
Rred:
Thanks for the insights. Based upon what you and others have said, perhaps what looked like rust was some other kind of staining on the paint.
Thanks for the insights. Based upon what you and others have said, perhaps what looked like rust was some other kind of staining on the paint.
Charles2
Contributor
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