Bob DBF
Contributor
The VCI done before the hydro is "unofficial" since the tank can't be approved for the VCI if the hydro is out of date. It is done before the hydro simply to check the tank to make sure that it would pass the VCI inspection since there is no sense of sending it for a hydro if it is going to fail the VCI test. The formal VCI is done after the hydro and is recorder properly with the new current hydro test.
A distinction without a difference. With the possible exception of the threads on an AL tank what will be the difference. Even then, with the AL tanks, DOT has not found it necessary to modify their procedures, although I don't know when, in the hydro procedures, the VE test is done on AL SP tanks.
Just because a private company has instituted a procedure to insure their graduates and dive shops get paid regardless of the legality or necessity of the procedure, does not make the tank safer than following the DOT procedures, which is what they say they train their students to do.
Bob