Requalification Requirements for Acetylene Cylinders
Pipeline and Hazardous Materials Safety Administration · Aug 20, 2001 · Reference No. 01-0128
Interprets: 49 CFR § 173.34, 49 CFR § 180.209
Reggie’s quick take
A company that does acetylene cylinder requalifications asked whether it may leave the examination and replacement of defective fuse plugs to its customer, who wants to do that part. The agency says no. Under § 173.34(e)(18)(ii), only a person holding a valid RIN may requalify an acetylene cylinder, and that RIN holder certifies the full requalification. So a company that skips the fuse plug work may not mark its RIN on the cylinder. The company also asked whether CGA C-13 allows any amount of extruded metal. The agency says no.
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 letter requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) concerning requalification requirements for acetylene cylinders. You state that you perform acetylene cylinder requalifications for a customer who asks that you not perform the examination and replacement of defective fuse plugs. You state that the customer wants to perform this portion of the requalification and you ask whether this is prohibited under the 49 CFR. You also ask whether "extruded metal" in paragraph 5.4.8 of the Compressed Gas Association's (CGA) pamphlet C-13 allows for any amount of extrusion without the cylinder being considered defective.
Section 173.34(e)(18)(ii) specifies that an aceytlene cylinder requalification may be performed only by a person holding a valid RIN (retester identification number). The person holding the RIN that is marked on the acetylene cylinder is the person certifying that the cylinder has been fully requalified in accordance with the requirements in § 173.34 and CGA pamphlet C-13. Therefore, if you do not perform the examination and replacement of defective fuse plugs, you may not mark your RIN number on the cylinder.
With regard to whether the examination for extruded metal in accordance with the CGA pamphlet C-13, allows for any amount of extrusion without being considered defective, the answer is no.
I hope this information is helpful. Please contact this office if we may be of further assistance.
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.