# American Bureau of Shipping — Hazardous Materials Safety Interpretation **Citation:** 22-0129 **Type / status:** guidance / guidance **Agency:** Pipeline and Hazardous Materials Safety Administration **Effective:** Not stated **Published:** 2023-03-21 22-0129 response to American Bureau of Shipping concerning 173.320, 178.274. ## Document text <<>> U.S. Department of Transportation Pipeline and Hazardous Materials Safety Administration 1200 New Jersey Avenue, SE Washington, DC 20590 March 21, 2023 Ms. Simone Goncalves Technical Manager American Bureau of Shipping 1701 City Plaza Drive Spring, TX 77389 Reference No. 22-0129 Dear Ms. Goncalves: This letter is in response to your November 30, 2022, email and subsequent telephone conversations with a member of my staff requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) applicable to the testing of portable tanks. Specifically, you ask whether there are any “exemptions” from the dynamic longitudinal impact test requirement, specified in § 178.274(j)(6), for portable tanks containing “UN1977, Nitrogen, refrigerated liquid, 2.2” by highway transportation only. As specified in § 178.274(j)(6), United Nations (UN) portable tanks used for the dedicated transportation of “Helium, refrigerated liquid,” UN1963, and “Hydrogen, refrigerated liquid,” UN1966, that are marked “NOT FOR RAIL TRANSPORT” in letters of a minimum height of 10 cm (4 inches) on at least two sides of the portable tank are excepted from the dynamic longitudinal impact test. However, there are certain scenarios where non-specification portable tanks may be used when transported by highway. For example, § 173.320(a) states that “atmospheric gases and helium, cryogenic liquids, in Dewar flasks, insulated cylinders, insulated portable tanks, insulated cargo tanks, and insulated tank cars, designed and constructed so that the pressure in such packagings will not exceed 25.3 psig under ambient temperature conditions during transportation are not subject to the requirements of this subchapter when transported by motor vehicle or railcar except as specified in paragraphs (a)(1), (a)(2), and (a)(3) of this section.” Therefore, a highway shipment of “UN1977, Nitrogen, refrigerated liquid, 2.2” may be <<>> transported in a non-specification insulated portable tank, provided the portable tank is constructed so that the pressure will not exceed 25.3 psig under ambient temperature conditions during transportation and all applicable requirements of § 173.320 are met. 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 <<>> Wolcott 22-0129 From: INFOCNTR (PHMSA) To: Dodd, Alice (PHMSA) Cc: Hazmat Interps Subject: FW: Interpretation Dynamic Impact Test Date: Wednesday, November 30, 2022 3:25:16 PM Hi Alice, Please see the below interpretation request. Let us know if you need anything else. Regards, -Breanna From: Simone Goncalves Sent: Wednesday, November 30, 2022 11:31 AM To: INFOCNTR (PHMSA) Cc: Michael Kloesel ; Benninghoven, Neil (PHMSA) Subject: Interpretation Dynamic Impact Test CAUTION: This email originated from outside of the Department of Transportation (DOT). Do not click on links or open attachments unless you recognize the sender and know the content is safe. Dear Sir/Madam, I have a question regarding the dynamic impact test indicated in section 6.7.4.14.1 of IMDG and DoT 49 CFR 178.274 (j) (6). The regulations indicate that the dynamic impact test should be performed for portable tanks meeting the definition of containers in CSC. Is it possible to exempt the dynamic impact test for a cryogenic tank carrying Refrigerated Nitrogen (UN 1977) transported by road only? Also, could you please confirm that the dynamic impact test is applicable only for rail transportation? Please find my information below: Full Name: Simone Goncalves Physical Mailing Address: 1701 City Plaza Dr, Spring, TX 77389 Telephone Number: +1 936 900 2056 Best Regards, Simone Gonçalves Technical Manager Container Certification Department 281-877-6325 wk <<>> sgoncalves@eagle.org ## Provenance - Official: Yes - Source: - Source ID: `phmsa` - SHA-256: `6f43fee2e5fba142d4ef1770f7e3c8a669e39d8cba7d9807a937429e6408a900` - Retrieved: 2026-08-20T00:59:31.977Z - Exported: 2026-08-22T06:26:42.360Z - Document slug: `phmsa-interpretation-22-0129` ### Source metadata ```json { "materialSubtype": "interpretation", "interpretationArea": "hazardous_materials", "representation": "full_text_from_official_pdf", "companies": [ "American Bureau of Shipping" ], "individuals": [ "Ms. Simone Goncalves" ], "refIds": [ "22-0129" ], "catalogDates": [ "2023-03-21" ], "catalogParts": [ 173, 178 ], "catalogRowCount": 2, "sourceRecordUrls": [ "https://www.phmsa.dot.gov/node/73621" ], "linkedAttachmentUrls": [], "unavailableResponseUrls": [], "duplicateRepresentationUrls": [], "citedSections": [ "173.320", "173.320(a)", "178.274", "178.274(j)(6)" ], "catalogPageUrls": [ "https://www.phmsa.dot.gov/regulations/title49/section/173320", "https://www.phmsa.dot.gov/regulations/title49/section/178274" ], "pdfUrls": [ "https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/docs/standards-rulemaking/hazmat/interpretations/77416/220129_0.pdf" ], "representations": [ { "viewUrl": "https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/docs/standards-rulemaking/hazmat/interpretations/77416/220129_0.pdf", "detailUrl": null, "detailHtmlPath": null, "pdfUrl": "https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/docs/standards-rulemaking/hazmat/interpretations/77416/220129_0.pdf", "pdfArtifactPath": "data/sources/phmsa-interpretations/22-0129-f3f479395e.pdf", "pdfArtifactSha256": "059c41ec38018e2f221482e36d90b9cd10ed2fcc2ab91e46cc6ecad1bffa3947", "extractedTextPath": "data/sources/phmsa-interpretations/22-0129-f3f479395e.v2.txt", "extractedTextSha256": "36da9d2c154ac8879d3c08c5a818554a88e29822adcc741ae060c9aac0e7e19c", "pageCount": 4, "extractionVersion": 2 } ], "caveat": "Interpretations apply regulations to the facts presented and do not create independently enforceable requirements.", "jurisdiction": "US" } ```