When go fill tank they tell the date.
Most tanks need to be tested every 5 years.
Some new tanks well 10 years.
Dave
FYI the marks after the date [+*] is 10 years test date and over fill by 10%
https://welditmyself.com/gas-cylinder-date-stamp/#12-would-you-like-to-see-an-argon-tank-date-stamp-example
I thought I knew how to read these, but I guess I don't. When was this tank tested?
View attachment 1729944