{"operation":"document","citation":"21-0088","title":"N/A — Hazardous Materials Safety Interpretation","source_type":"guidance","agency":"Pipeline and Hazardous Materials Safety Administration","status":"guidance","official":true,"published_on":"2021-12-07","effective_on":null,"summary":"21-0088 response to N/A concerning 171.7, 178.35, 178.50.","machine_formats":{"json":"https://regulus.evalyn.ai/document/phmsa-interpretation-21-0088.json","markdown":"https://regulus.evalyn.ai/document/phmsa-interpretation-21-0088.md"},"app_url":"https://regulus.evalyn.ai/document/phmsa-interpretation-21-0088","source_url":"https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/2026-06/210088.pdf","body":"<<>>\n\nU.S. Department\nof Transportation\nPipeline and Hazardous\nMaterials Safety\nAdministration\n1200 New Jersey Avenue, SE\nWashington, DC 20590\nDecember 7, 2021\nReference No. 21-0088\nDear :\nThis letter is in response to your August 25, 2021, email requesting clarification of the\nHazardous Materials Regulations (HMR; 49 CFR Parts 171-180) applicable to Department of\nTransportation (DOT) 4B specification cylinders. In your email, you request clarification\nregarding lot sizes of cylinders related to the mechanical testing requirements and the associated\nreporting requirements in Compressed Gas Association (CGA) C-11 (2013), incorporated by\nreference in § 171.7 and cited in § 178.35. Specifically, you ask: (1) when should mechanical\ntesting be conducted for small batches of cylinders produced over a period of time; (2) how to\ndocument production over a period of time; and (3) when is the shipping of such cylinders\nauthorized.\nThe HMR outline the specifications for DOT 4B welded or brazed steel cylinders in § 178.50.\nThe requirements for mechanical testing in § 178.50(j) state that testing is required on two\nspecimens removed from one cylinder, or part thereof, and with specimen samples selected in\naccordance with appendix A to Part 178 after heat treatment. Paragraph (c) of § 178.35 requires\nthat a cylinder inspection must conform to CGA C-11 (2013), except as otherwise specified in\nthe applicable specification. CGA C-11 (2013) describes a “lot” as “a quantity of cylinders\nhaving the same size, design, construction, material grade, and heat treatment—when\napplicable—that are designated by the manufacturer for approval through sample testing as\ndefined by the applicable regulations.” Therefore, since each batch of DOT 4B cylinders\nrequires heat treatment (see § 178.50(g)), the batches of cylinders you describe would be\nconsidered a lot on their own, and each lot would be subject to mechanical testing. This testing\nis required to be documented in accordance with Appendix E to CGA C-11 (2013). Cylinder lots\nthat conform to the mechanical testing requirements and documented in accordance with\nAppendix E to CGA C-11 (2013) would be authorized for transportation under the HMR.\n\n<<>>\n\nFinally, please note that as specified in § 178.50(j)(1), mechanical tests are authorized to be\nmade on a ring at least 8 inches long removed from each cylinder and subjected to the same heat\ntreatment as the finished cylinder for lots of 30 cylinders or fewer.\nIf you are unable to demonstrate compliance with the testing requirements, you may apply for a\nspecial permit by submitting an application to the Associate Administrator for Hazardous\nMaterials Safety in conformance with the requirements prescribed in 49 CFR Part 107, Subpart\nB. You may obtain information on the special permit application process from our website at\nhttps://www.phmsa.dot.gov/approvals-and-permits/hazmat/hazardous-materials-approvals-and-\npermits-overview, or by calling PHMSA's General Approvals and Permits branch within the\nStandards and Rulemaking Division at (202) 366-4511.\nI hope this information is helpful. Please contact us if we can be of further assistance.\nSincerely,\nT. Glenn Foster\nChief, Regulatory Review and Reinvention Branch\nStandards and Rulemaking Division\n\n<<>>\n\nAndrews\n21-0088\nFrom: INFOCNTR (PHMSA)\nTo: Dodd, Alice (PHMSA)\nCc: Hazmat Interps\nSubject: FW: Test requirements for a small volume manufacturer of DOT 4B cylinders\nDate: Friday, August 27, 2021 12:57:23 PM\nAttachments: image010.png\nimage011.png\nimage012.png\nHello Alice,\nPlease see the below interpretation request from .\nLet us know if you need anything else from us.\nRegards,\n-Breanna\nFrom: Approvals (PHMSA) \nSent: Friday, August 27, 2021 7:02 AM\nTo: INFOCNTR (PHMSA) \nSubject: FW: Test requirements for a small volume manufacturer of DOT 4B cylinders\nletter of Interpretation request\nNeil Benninghoven\nTransportation Specialist, Pressure Vessels Branch PHH25\nUS Department of Transportation\nPipeline and Hazardous Materials Safety Administration\n1200 New Jersey Ave., SE\nWashington, D.C. 20590-0001\nOffice: 202-366-2665 ◊ Mobile: 202-573-4342\nPHMSA Home | LinkedIn | Twitter | HAZMAT | OPS\nFrom: >\nSent: Thursday, August 26, 2021 3:37 PM\nTo: Approvals (PHMSA) \nSubject: RE: Test requirements for a small volume manufacturer of DOT 4B cylinders\nCAUTION: This email originated from outside of the Department of Transportation (DOT). Do not click on links or\nopen attachments unless you recognize the sender and know the content is safe.\nI neglected to add that the request for interpretation as well as our correspondence related to\n\n<<>>\n\nthis inquiry should be treated as confidential information as per 49 CFR 105.30.\nBy the way our .\nBest Regards,\nThis message is a private communication and may contain confidential information and may not be used or relied upon by\nanyone other than the intended recipient. If you are not the intended recipient, please do not use or disclose any of the\ninformation contained in the message or forward the message to anyone else, either in printed or electronic form. Please notify\nthe sender of the delivery error by replying to this message, and then delete it from your system.\nFrom:\nSent: Wednesday, August 25, 2021 12:34 PM\nTo: Approvals (PHMSA) \nSubject: Test requirements for a small volume manufacturer of DOT 4B cylinders\nWe request a letter of Interpretation regarding clarification of a lot size, mechanical testing\nrequirements, and CGA C-11 reporting requirements.\nWe are a small volume manufacturer and produce a lot over a period of time in small batches of 10\ncylinders or less. It may be up to a year or more before we complete a lot size of 200 for a particular\ngroup of DOT 4B cylinders. Currently, hydrostatic testing and mechanical tests are performed on the\nfirst small batch of cylinders within a lot. We are asking for clarification as to when mechanical\ntesting should be conducted for a lot produced over a period of time in small batches within the\nsame lot, how to document lot production over time and when shipping of cylinders within a lot is\nauthorized.\nThanks in advance,\n\n<<>>\n\nBest Regards,\nThis message is a private communication and may contain confidential information and may not be used or relied upon by\nanyone other than the intended recipient. If you are not the intended recipient, please do not use or disclose any of the\ninformation contained in the message or forward the message to anyone else, either in printed or electronic form. Please notify\nthe sender of the delivery error by replying to this message, and then delete it from your system.\nDisclaimer\nThis message is a private communication and may contain confidential information and may not be used or\nrelied upon by anyone other than the intended recipient. If you are not the intended recipient, please do not\nuse or disclose any of the information contained in the message or forward the message to anyone else,\neither in printed or electronic form. Please notify the sender of the delivery error by replying to this\nmessage, and then delete it from your system.\nThis email has been scanned for viruses and malware, and may have been automatically archived by\nMimecast Ltd","truncated":false,"body_characters":7328}