Thread drift. ::shrug::
There is no basis in law, fact, regulation, or history for the idea that it is necessary to perform an annual inspection to the same standards as the visual portion of the 5-year requalification ("hydro") required by the USDOT. We owe the insistence on an annual VIP to the rupture of three steel 72 cubic foot cylinders in the 1970s. The cylinders had been partially filled with sea water due to the then-standard practice of breathing a cylinder until it is completely empty before surfacing from a dive. They corroded and failed. The annual visual inspection was originally just a quick look inside the cylinder to see whether this type of obvious corrosion had occurred since the last 5-year requalification ("hydro").
PSI came along and put together a much more rigorous inspection program for the paranoid and lawsuit averse. It is based not on looking for evidence that new corrosion since the last requalification ("hydro") was completed, but rather performing a new inspection, ab initio, to the same standard as the requalification except for the hydrostatic portion of the test (which all but a few dive shops cannot perform as they do not have the equipment).
There is no evidence that this improves safety, let alone any evidence that 12 months is the best interval to use. (Why not six months? 24 months? 30 months so it is midway between hydros?)
As for the language on the stickers, well, PSI and the like are protecting their business model and trying to help their customers (dive shops) deflect the blame in the event an accident should occur.
