Cylinder Retesting
Pipeline and Hazardous Materials Safety Administration · Sep 25, 2001 · Reference No. 01-0144
Interprets: 49 CFR § 173.34, 49 CFR § 180.209
Reggie’s quick take
Someone asked whether a 1955 DOT 3AA cylinder that has been hydrostatically tested and exceeds the elastic expansion limit in CGA Pamphlet C-5 can keep its "star" marking and be retested every 10 years. PHMSA says yes, but only if the cylinder meets § 173.34(e)(16) and the other requalification rules in § 173.34, such as the maximum permanent expansion limit.
Written by AI (Claude) on Oct 22, 2026. Robots make mistakes and leave things out, so the letter below is what counts. Not legal advice.
This is in response to your June 1, 2001 letter concerning the periodic requalification requirements in 49 CFR 173.34(e). You asked whether a DOT Specification 3AA cylinder manufactured in 1955 that has been hydrostatically tested and exceeds the elastic expansion rejection limit listed in CGA Pamphlet C-5 can continue to be marked with a "star" marking and tested at 10 year intervals.
The answer is yes, if the cylinder meets the requirements of § 173.34(e)(16) and the other requalification requirements of § 173.34 such as the maximum allowed permanent expansion.
I hope this information is helpful.
A letter of interpretation applies the regulations to the facts the requester described. It isn’t a regulation and isn’t legal advice. The agency’s copy.