Have been speaking to a few of the guys at IDEST/SITA (many thanks Pat/Neil) about date stamping. Apologies all of the below is common knowledge but it became apparent that there were some differing views .
From 2000 until 2012 the year must be stamped as YYYY and the month will always be MM. Therefore the dates between 2000 and 2012 will be YYYY/MM.
From 2013, and because there will never be a month 13 so the year stampings can be abbreviated to YY/MM (13/07 in the case of July 2013). If a test house wish to continue with the full YYYY for the year, this is acceptable.
Visuals and Hydrostatic tests
If a cylinder has missed it's visual (2.5 years from hydro) it CAN have a visual...if all is OK it can then be used for the remaining time since its last hydro. But it MUST have a hydro after 5 years from it last hydro.
2010 - tank has a hydro
2012 (end of June) - due date of visual, visual inspection missed.
Note: Persons should not be filling the tank after this date without insisting on a visual.
2013 - tank is visually inspected and if all is OK* has 2 years of usage (not 2.5) before it's scheduled hydro in 2015
2015 - next hydro
*IF on visual inspection it needs to be shot blasted it must have a hydro. All subsequent hydrostatic tests would then be from the new date.