Rust and steel tanks

[Panulirus]

I've got a couple of PST 100's that are a year and a half old. Both recently failed VIP and are being sent out to be tumbled and hydroed because of rust and condensation. Obviously I wasn't thrilled when the dive shop called to give me the bad news. Just wondering if others have had the same experience with relatively new steels. The captain of the boat that we regularily dive with recently informed my wife and I to check with whoever fills our tanks to see when the last time was that they changed filters on their compressor. Normal change time I guess is around 30 hours. He said if it's anywhere close to that to hold off until they do the change. Otherwize he claims you are going to end up with rust in steel tanks. My tanks have always been filled with Nitrox by the same shop that I bought them from using a membrane system. Any comments welcome just trying to avoid this hastle in the future.

 

[Dive Right In Scuba]

Unless your not keeping air in them when storing, or are completely draining them during dives........it sounds like your getting bad air.....meaning they might not be regularly changing their filters.....Just my guess with what you provided.....

 

[rjack321]

Every boat compressor I've ever seen is pumping wet gas. Avoid boat fills if you want to avoid rust.

 

[somewhereinla]

I agree, boats are notorious for problems with wet/salty air.

 

[Igodeep]

Yep, boats are a good place to pick up moisture. If you suspect wet air, open the tank up and dry it with a hair dryer when you get home. You can also use an oxygen compatable rust inhibitor in the tank to help prevent the surface rust.

 

[Slipstrm]

I've got a couple of PST 100's that are a year and a half old. Both recently failed VIP and are being sent out to be tumbled and hydroed because of rust and condensation.

I have seen HP PST tanks that have only had 3 fills that were rusted, a friend of mine has a set that were manufactured at the same time, had three clean dry fills apiece, and one was rusted badly at the first VIP. I believe it was due to a failure by PST to dry the tanks well on the initial hydro.
It was pretty bad, but after a phosphoric acid cleaning it looked like new.

 

[Jay Roy]

The tumble job I can understand, but why the hydro test?

 

[JBRES1]

The tumble job I can understand, but why the hydro test?

After a tumble , you need to re hydro to make sure the tank is ok.
Tumbleing media can remove material from the inside of the tank other than the rust.
Jim Breslin

 

[Tigerman]

A year and a half old and rusted
That sounds awful bad..

 

[carbon]

You can also use an oxygen compatable rust inhibitor in the tank to help prevent the surface rust.

Wow, I have never heard of this. Do you have the names of any particular products, and how are the applied and used?

Thanks!
carbon