Originally Posted by n0buddy0
Yes, it technically would need to have re-certification done every 5 years (see CFR links above). However, most fields and shops will ignore that, and just follow that "under 2 inch ..." rumor rule. Which is a good thing, imho. Just mind
1) damaging the tank and blowing up yourself and/or others.
2) if you're traveling, or if someone does check your equipment for safety compliance - be aware that you will not pass.
How about this? Page 323, Table 1, note 1. https://www.gpo.gov/fdsys/pkg/CFR-201...sec180-209.pdf
1 Any cylinder not exceeding 2 inches outside diameter and less than 2 feet in length is excepted from volumetric expansion