Interpretation Response #21-0088
Below is the interpretation response detail and a list of regulations sections applicable to this response.
Interpretation Response Details
Response Publish Date:
Company Name: N/A
Individual Name: N/A
View the Interpretation Document
Response text:
December 7, 2021
[REDACTED]
Reference No. 21-0088
Dear[REDACTED]:
This letter is in response to your August 25, 2021, email requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) applicable to Department of Transportation (DOT) 4B specification cylinders. In your email, you request clarification regarding lot sizes of cylinders related to the mechanical testing requirements and the associated reporting requirements in Compressed Gas Association (CGA) C-11 (2013), incorporated by reference in § 171.7 and cited in § 178.35. Specifically, you ask: (1) when should mechanical testing be conducted for small batches of cylinders produced over a period of time; (2) how to document production over a period of time; and (3) when is the shipping of such cylinders authorized.
The HMR outline the specifications for DOT 4B welded or brazed steel cylinders in § 178.50. The requirements for mechanical testing in § 178.50(j) state that testing is required on two specimens removed from one cylinder, or part thereof, and with specimen samples selected in accordance with appendix A to Part 178 after heat treatment. Paragraph (c) of § 178.35 requires that cylinder inspection must conform to CGA C-11 (2013), except as otherwise specified in the applicable specification. CGA C-11 (2013) describes a "lot" as "a quantity of cylinders having the same size, design, construction, material grade, and heat treatment—when applicable—that are designated by the manufacturer for approval through sample testing as defined by the applicable regulations." Therefore, since each batch of DOT 4B cylinders requires heat treatment (see § 178.50(g)), the batches of cylinders you describe would be considered a lot on their own, and each lot would be subject to mechanical testing. This testing is required to be documented in accordance with Appendix E to CGA C-11 (2013). Cylinder lots that conform to the mechanical testing requirements and documented in accordance with Appendix E to CGA C-11 (2013) would be authorized for transportation under the HMR. Finally, please note that as specified in § 178.50(j)(1), mechanical tests are authorized to be made on a ring at least 8 inches long removed from each cylinder and subjected to the same heat treatment as the finished cylinder for lots of 30 cylinders or fewer.
If you are unable to demonstrate compliance with the testing requirements, you may apply for a special permit by submitting an application to the Associate Administrator for Hazardous Materials Safety in conformance with the requirements prescribed in 49 CFR Part 107, Subpart B. You may obtain information on the special permit application process from our website at https://www.phmsa.dot.gov/approvals-and-permits/hazmat/hazardous-materials-approvals-and-permits-overview, or by calling PHMSA's General Approvals and Permits branch within the Standards and Rulemaking Division at (202) 366-4511.
I hope this information is helpful. Please contact us if we can be of further assistance.
Sincerely,
T. Glenn Foster
Chief, Regulatory Review and Reinvention Branch
Standards and Rulemaking Division