{"operation":"document","citation":"24-0082","title":"Office of Railroad, Pipeline and Hazardous Materials Investigations National Transportation Safety Board — Hazardous Materials Safety Interpretation","source_type":"guidance","agency":"Pipeline and Hazardous Materials Safety Administration","status":"guidance","official":true,"published_on":"2025-03-26","effective_on":null,"summary":"24-0082 response to Office of Railroad, Pipeline and Hazardous Materials Investigations National Transportation Safety Board concerning 171.8, 172.102, 176.2.","machine_formats":{"json":"https://regulus.evalyn.ai/document/phmsa-interpretation-24-0082.json","markdown":"https://regulus.evalyn.ai/document/phmsa-interpretation-24-0082.md"},"app_url":"https://regulus.evalyn.ai/document/phmsa-interpretation-24-0082","source_url":"https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/2025-03/240082.pdf","body":"<<<PAGE 1>>>\n\nU.S. Department\nof Transportation\nPipeline and Hazardous\nMaterials Safety\nAdministration\n1200 New Jersey Avenue, SE\nWashington, DC 20590\nMarch 26, 2025\nRachael Gunaratnam\nHazardous Materials Accident Investigator\nOffice of Railroad, Pipeline and Hazardous Materials Investigations\nNational Transportation Safety Board\n490 L’Enfant Plaza, SW\nWashington, DC 20594\nReference No. 24-0082\nDear Ms. Gunaratnam:\nThis letter responds to the September 11, 2024 letter that you submitted on behalf of the National\nTransportation Safety Board (NTSB). In that letter, NTSB asks the Office of Hazardous\nMaterials Safety (OHMS) to clarify the requirements in the Hazardous Materials Regulations\n(HMR; 49 CFR Parts 171-180) that apply to the bulk transport by vessel of lithium batteries that\nare installed in a battery energy storage system (BESS). NTSB’s understanding is that the\nrequirements in special provision (SP) 389 apply to “UN3536, Lithium batteries installed in\ncargo transport unit” because the BESS is a freight container that meets the definition of a cargo\ntransport unit (CTU) under the HMR. Based on that understanding, NTSB presents a series of\nquestions to OHMS about the applicability of certain requirements in the HMR to the BESS.\nOHMS has paraphrased and answered your questions as follows:\nQ1. What are the performance criteria or specifications for a freight container used as a CTU\nwhen transporting “UN3536, Lithium batteries installed in cargo transport unit”?\nA1. A freight container meets the definition of a CTU under the HMR. As noted in your\nletter, a CTU is defined, in relevant part, as “a transport vehicle, a freight container, a\nportable tank or a multiple element gas container.” 49 CFR § 176.2. A freight container\nis “a reusable container having a volume of 64 cubic feet or more, designed and\nconstructed to permit being lifted with its contents intact and intended primarily for\ncontainment of packages (in unit form) during transportation.” 49 CFR § 171.8.\nAdditional performance criteria, as provided in SP 389 and assigned to the UN3536 entry\nin the Hazardous Materials Table, states that “the batteries must be securely attached to\nthe interior structure of the cargo transport unit (e.g., by means of placement in racks,\ncabinets, etc.) in such a manner as to prevent short circuits, accidental operation, and\n\n<<<PAGE 2>>>\n\nsignificant movement relative to the cargo transport unit under the shocks, loadings, and\nvibrations normally incident to transport.” 49 CFR § 172.102(c)(1)(389).\nQ2. If the cabinet used for the BESS described in NSTB’s letter is a freight container that\nmeets the definition of a CTU under the HMR, which standards or specifications apply\nwhen a CTU is used to transport “UN3536, Lithium batteries installed in cargo transport\nunit” by vessel or highway?\nA2. The cabinet described in NTSB’s letter that houses the BESS is a freight container that\nmeets the definition of a CTU as defined in the HMR. See 49 CFR § 176.2. There are\nrequirements in the HMR for CTUs such as the one in the BESS described. See answer\nA1 for the relevant performance criteria in SP 389.\nQ3. Is a “high sea state” with significant speed winds and wave heights considered normal\nconditions for the transportation of hazardous materials by vessel?\nA3. The HMR do not specifically define conditions normally incident to transportation;\nhowever, a “high sea state” refers to rough and potentially dangerous ocean conditions\nwith large waves, typically caused by strong winds or storms. While it is not\nunreasonable for a vessel to expect to encounter such rough seas during an ocean\ncrossing, depending on the severity of the storm, such conditions may be considered\nabnormal.\nQ4. Does the fact that the air conditioning system for a BESS is not energized during\ntransportation imply that such a system is not “necessary for the safe and proper\noperation of the cargo transport unit” under SP 389 and the HMR?\nA4. No. The mere fact that the air conditioning system for a BESS is not operating in\ntransportation does not mean that such a system is not necessary for the safe and proper\noperation of the CTU in accordance with SP 389 and the HMR. An air conditioning\nsystem could be necessary for the safe and proper operation of the CTU if the BESS is in\noperation and actively providing power external to the CTU. The fact that the system is\nnot operational during transportation would not affect the compliance obligations\nimposed under SP 389 and the HMR. If, on the other hand, an air conditioning system is\nonly used for purposes other than the safe and proper operation of the CTU, the standard\nprescribed in SP 389 and the HMR would not be met. In this case, the air conditioning\nsystem must not be transported within the CTU.\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<<<PAGE 3>>>\n\nLarson\n24-0082\nFrom: INFOCNTR (PHMSA)\nTo: Hazmat Interps\nSubject: FW: NTSB request for a letter of interpretation\nDate: Friday, September 13, 2024 12:56:28 PM\nAttachments: NTSB request_ Letter of Interpretation_final.pdf\nHello Hazmat Interps,\nPlease see attached request for letter of interpretation.\nThanks,\nJonathon, HMIC\nFrom: Rachael Gunaratnam <rachael.gunaratnam@ntsb.gov>\nSent: Thursday, September 12, 2024 1:29 PM\nTo: PHMSA HM InfoCenter <PHMSAHMInfoCenter@dot.gov>\nCc: Kelley, Shane (PHMSA) <shane.kelley@dot.gov>; DerKinderen, Dirk (PHMSA)\n<Dirk.DerKinderen@dot.gov>; Robert Clatterbuck <Robert.Clatterbuck@ntsb.gov>; David Flaherty\n<david.flaherty@ntsb.gov>\nSubject: NTSB request for a letter of interpretation\nCAUTION: This email originated from outside of the Department of Transportation (DOT). Do\nnot click on links or open attachments unless you recognize the sender and know the content\nis safe.\nGood Afternoon,\nPlease see the attached request for a letter of interpretation regarding the Hazardous\nMaterials Regulations (HMR; 49 CFR Parts 171-180).\nThank you,\nRachael Gunaratnam\nHazardous Materials Accident Investigator\nOffice of Railroad, Pipeline and Hazardous Materials Investigations\nNational Transportation Safety Board\n490 L’Enfant Plaza, SW\nWashington, D.C. 20594\nCONFIDENTIALITY NOTICE - THIS E-MAIL TRANSMISSION MAY CONTAIN INFORMATION THAT\nIS PRIVILEGED, CONFIDENTIAL, PROPRIETARY, SUBJECT TO COPYRIGHT, AND/OR EXEMPT\nFROM DISCLOSURE UNDER APPLICABLE LAW. IT IS FOR THE USE OF INTENDED RECIPIENTS\nONLY. If you are not an intended recipient of this message, please notify the original sender\nimmediately by forwarding what you received and then delete all copies of the\n\n<<<PAGE 4>>>\n\ncorrespondence and attachments from your computer system. Any use, distribution, or\ndisclosure of this message by unintended recipients is not authorized and may be unlawful.\nCONFIDENTIALITY NOTICE - THIS E-MAIL TRANSMISSION MAY CONTAIN INFORMATION THAT IS\nPRIVILEGED, CONFIDENTIAL, PROPRIETARY, SUBJECT TO COPYRIGHT, AND/OR EXEMPT FROM\nDISCLOSURE UNDER APPLICABLE LAW. IT IS FOR THE USE OF INTENDED RECIPIENTS ONLY. If you are\nnot an intended recipient of this message, please notify the original sender immediately by\nforwarding what you received and then delete all copies of the correspondence and attachments\nfrom your computer system. Any use, distribution, or disclosure of this message by unintended\nrecipients is not authorized and may be unlawful.\n\n<<<PAGE 5>>>\n\nNational Transportation Safety Board\nOffice of Railroad, Pipeline and Hazardous Materials\nWashington, DC 20594\nSeptember 11, 2024\nU.S. Department of\nTransportation\n1200 New Jersey Ave, SE\nWashington, DC 20590\nTo whom it may concern,\nI am requesting a letter of interpretation regarding the regulations that apply to bulk\ntransport of UN 3536 lithium battery shipments of a battery energy storage system\n(BESS) by vessel. Currently, PHMSA regulations, similar to the International Maritime\nDangerous Goods Code for international shipments, requires special provision 389\nfor UN 3536, “Lithium batteries installed in cargo transport unit.” Special provision\n389 under 49 CFR 172.102 states:\nThis entry only applies to lithium ion batteries or lithium metal batteries installed in a cargo\ntransport unit and designed only to provide power external to the cargo transport unit. The\nlithium batteries must meet the requirements of § 173.185(a) and contain the necessary\nsystems to prevent overcharge and over discharge between the batteries. The batteries must\nbe securely attached to the interior structure of the cargo transport unit (e.g., by means of\nplacement in racks, cabinets, etc.) in such a manner as to prevent short circuits, accidental\noperation, and significant movement relative to the cargo transport unit under the shocks,\nloadings, and vibrations normally incident to transport. Hazardous materials necessary for the\nsafe and proper operation of the cargo transport unit (e.g., fire extinguishing systems and air\nconditioning systems), must be properly secured to or installed in the cargo transport unit and\nare not otherwise subject to this subchapter. Hazardous materials not necessary for the safe\nand proper operation of the cargo transport unit must not be transported within the cargo\ntransport unit. The batteries inside the cargo transport unit are not subject to marking or\nlabelling requirements of part 172 subparts D and E of this subchapter. The cargo transport\nunit shall display the UN number in a manner in accordance with § 172.332 of this subchapter\nand be placarded on two opposing sides. For transportation by aircraft, cargo transport units\nmay only be offered for transportation and transported under conditions approved by the\nAssociate Administrator.\nA cargo transport unit under 49 CFR 176.2 is defined as:\nA cargo transport unit means a transport vehicle, a freight container, a portable tank or a\nmultiple element gas container (MEGC). A closed cargo transport unit means a cargo transport\nunit in which the contents are totally enclosed by permanent structures. An open cargo\ntransport unit means a cargo transport unit that is not a closed cargo transport unit. Cargo\ntransport units with fabric sides or tops are not closed cargo transport units for the purposes of\nthis part.\n\n<<<PAGE 6>>>\n\n2\nI am requesting clarification on the following:\n1) As defined under Part 176.2, a CTU is a transport vehicle, freight container,\nportable tank and multiple element gas container. For a UN 3536 BESS, only a\nfreight container would apply and is defined under PHMSA regulations under Part\n171.8:\nFreight container means a reusable container having a volume of 64 cubic feet or\nmore, designed and constructed to permit being lifted with its contents intact and\nintended primarily for containment of packages (in unit form) during\ntransportation.\nIs there performance packaging or specifications for a CTU/freight container for a\nUN 3536 lithium battery that is shipped by vessel or highway? If yes, what is the\nstandard?\n2) The NTSB is currently investigating an incident involving a Battery Energy Storage\nSegment (BESS). A similar model of the BESS involved in the incident is illustrated\nin PHMSA’s letter of interpretation Reference No. 22-0131, as seen below in Figure\n1. The NTSB would like clarification if the cabinet that housed the lithium ion\nbatteries is considered a cargo transport unit. If the cabinet itself is a CTU, what\nperformance criteria must be met before the cabinet is transported by vessel or\nhighway?\nFigure 1: Exemplar Model of a BESS\n\n<<<PAGE 7>>>\n\n3\n3) When shipping a hazardous materials package by sea, the vessel may encounter a\nhigh sea state with significant speed winds and wave heights.1 Is a high sea state,\nsuch as gale force conditions, considered normal conditions of transportation by\nvessel?\n4) Special Provision 389 notes the following:\n“Hazardous materials necessary for the safe and proper operation of the cargo transport unit (e.g.,\nfire extinguishing systems and air conditioning systems), must be properly secured to or installed\nin the cargo transport unit and are not otherwise subject to this subchapter”\n.\nThe cargo transport units referenced above were equipped with an air\nconditioning system that was not energized during shipment. Since the system\nwas not energized during shipment, would that imply that the air conditioning\nsystem was not “necessary for the safe and proper operation” of the cargo\ntransport unit?\nSincerely,\nRachael Gunaratnam\nSr. Hazardous Materials Investigator\nNational Transportation Safety Board\ncc: LT Joshua Murdy, U.S. Coast Guard\n1 See “Beaufort Wind Scale”, Storm Prediction Center, NOAA/National Weather Service,\nhttps://www.spc.noaa.gov/faq/tornado/beaufort.html.","truncated":false,"body_characters":12767}