I have a couple of Steel 72's that have a Hydro stamp from 1973 (so they're more than 30 years old). They are great tanks. When I had them VIPed in August - the inspector said they were so clean inside - nearly perfect (I looked too - very very clean)
The most recent Hydro is from 2005 with the + rating.
The most recent Hydro is from 2005 with the + rating.