How fast can rust form in a steel tank?

[ChrisA]

How long does it take for rust to form inside a steel tank? I have a PST LP80 with a May 2004 VIP and had to take the valve off today in june 04. (The tube under valve fell off.) There is a light bit of rust inside. Could it really have been clean in May and now in June be in need of cleaning already?

Thanks all. You provided enough information that I could talk with the shop's tech. in an informed manner. Yes the "dip tube" did fall loose caused by someones failure to install it tight enough. The rust was "flash rust". The guy at the shop showed me how he checks steel tanks and what "flash" looks like and bad rust looks like. He said a tank is good if the rust is only at the surface, no pits or flakes and he whacks the tank all over with a rubber mallet then inverts the tank and taps the neck on a clean white surface and looks for dust.

 

[drbill]

My understanding is that the PST hot dip galvanzining is only on the outside. They are also well know for having an orange-red color inside which is not necessarily due to rust but to the galvinizing process (or so I was told). However I have also heard of several tanks that rusted in less than a year, probably from water introduced into them on dive boats.

Doc