{"operation":"document","citation":"25-0115","title":"NeoWave S.A.S. de C.V. — Hazardous Materials Safety Interpretation","source_type":"guidance","agency":"Pipeline and Hazardous Materials Safety Administration","status":"guidance","official":true,"published_on":"2026-03-19","effective_on":null,"summary":"25-0115 response to NeoWave S.A.S. de C.V. concerning 173.33, 178.345, 180.405, 180.413.","machine_formats":{"json":"https://regulus.evalyn.ai/document/phmsa-interpretation-25-0115.json","markdown":"https://regulus.evalyn.ai/document/phmsa-interpretation-25-0115.md"},"app_url":"https://regulus.evalyn.ai/document/phmsa-interpretation-25-0115","source_url":"https://www.phmsa.dot.gov/standards-rulemaking/hazmat/interpretations/25-0115","body":"<<<PAGE 1>>>\n\n1200 New Jersey Avenue, SE\nWashington, DC 20590\nU.S. Department\nof Transportation\nPipeline and Hazardous\nMaterials Safety\nAdministration\nMarch 19, 2026\nFrancisco Davila\nRegistered Inspector\nNeoWave S.A.S. de C.V.\nHacienda Monte Real 107\nHacienda El Campanario\nApodaca, Nuevo Leon, Mexico 66643\nReference No. 25-0115\nDear Mr. Davila:\nThis letter is in response to your August 7, 2025 letter requesting clarification of the Hazardous\nMaterials Regulations (HMR; 49 CFR Parts 171-180) applicable to cargo tank modifications.\nSpecifically, you state that you are inquiring about modifying a cargo tank to a different\nspecification than that which it was originally built. You state that some manufacturers, repair\nfacilities, and registered inspectors are under the assumption that a Motor Carrier (MC) 300-\nseries cargo tank can have its name plate modified to reflect a current Department of\nTransportation (DOT) 400-series specification if that cargo tank meets the requirements outlined\nin §§ 178.345 through 178.348. You ask a series of questions regarding the modification of MC\n300-series cargo tanks.\nWe have paraphrased and answered your questions as follows:\nQ1. You ask whether § 180.405(b)(2) allows for the recertification of MC 306, MC 307, and\nMC 312 cargo tanks to their original specification.\nA1. Yes, § 180.405(b)(2) allows cargo tanks originally manufactured as MC 306, MC 307,\nand MC 312 cargo tanks to be recertified to their original specification. This serves as an\nexception to paragraph (b)(1) of that section which states that no cargo tank may be\nmarked or certified after August 31, 1995, to the applicable MC 306, MC 307, MC 312,\nMC 331, or MC 338 standard for that specification in effect on December 30, 1990. This\nallows a registered inspector to recertify an MC 306, MC 307, or MC 312 cargo tank\nafter it has been modified.\nQ2. You ask whether § 180.405(c)(2) allows MC 300-series cargo tanks to have their pressure\nrelief devices (PRDs) and outlets modified to conform to DOT 400-series cargo tank\nspecifications.\n\n<<<PAGE 2>>>\n\nA2. Yes, MC 300-series cargo tanks may have their PRDs and outlets modified to meet\ncertain DOT 400-series specifications as authorized by § 173.33(d)(3) and\n§ 180.405(c)(2). PHMSA previously amended the HMR in a final rule, HM-183, to\ndiscontinue the construction of MC 300-series cargo tanks and authorized the use of DOT\n400-series PRDs on the remaining in-service MC 300-series cargo tanks.a\nQ3. You ask whether it is permissible, if a cargo tank complies with the regulations\napplicable to a DOT 400-series cargo tank, to change the specification on the nameplate\nfrom showing MC 300-series to show DOT 400-series.\nA3. Yes, the HMR allows for the modification, stretching, or rebarrelling of only those listed\nMC 300-series cargo tanks to the corresponding DOT 400-series specifications specified\nin § 180.413(d)(2)(i) through (iii). All the provisions in § 180.413(d)(1) through (d)(4)\nmust be met for modifications, including the installation of a supplemental specification\nplate, nameplate, or both containing the information that reflects the cargo tank as\nmodified, stretched, or rebarrelled.\nI hope this information is helpful. Please contact us if we can be of further assistance.\nSincerely,\nAlexander Wolcott\nActing Chief, Regulatory Review and Reinvention Branch\nStandards and Rulemaking Division\na 54 FR 24982 (Jun. 12, 1989)\n\n<<<PAGE 3>>>\n\nNeoWave S.A.S. de C.V.\nR.F.C.: NEO230628AS6\nHacienda Monte Real 107, Hacienda El Campanario\nApodaca, Nuevo León, México, 66643\n+52 (813) 593-0901 contacto@neowave.mx\nAugust 7, 2025\nLarson, R.\n25-0115\nStandards and Rulemaking Division\nPipeline and Hazardous Materials Safety Administration, Attn: PHH-10\nU.S. Department of Transportation\n1200 New Jersey Avenue, SE East Building, 2nd Floor\nWashington, DC 20590\nphmsa.hm-infocenter@dot.gov\nRequest for Interpretation\nTo whom it may concern,\nI am writing to inquire about the possibility of modifying a cargo tank to a different specification than the one it was\noriginally manufactured under.\nSome manufacturers, repair facilities, and registered inspectors operate under the presumption that a cargo tank in\nthe MC 3XX series can have its name plate modified to reflect a current DOT 4XX series, since the cargo tank meets\nthe requirements outlined in §§178.345 through 178.348.\nAccording to §180.405, which addresses the qualification of cargo tanks, paragraph (b) states that a cargo tank\noriginally manufactured to, and I quote, “the MC 306, MC 307, or MC 312 specification may be recertified to the original\nspecification provided” it meets the requirements further outlined in that paragraph.\nAdditionally, §180.405(c)(2) states that a cargo tank listed in paragraph (c)(1) of the same section may have its pressure\nrelief devices and outlets modified to conform to a newer specification.\nSo, the following questions arise:\n1) If a cargo tank complies with all current regulations applicable to the DOT 4XX series, is it permissible to\nchange the specification on the name plate from an MC 3XX series to a DOT 4XX series?\n2) If the answer to the previous question is no, how should the regulations be interpreted to support the\nconclusion that the cargo tank cannot be reclassified from its original specification?\nI truly appreciate your attention to this matter.\nSincerely,\nFrancisco Davila | Registered Inspector\nEmail: francisco.davila@neowave.mx\nMobile: +52 (818) 011-1643\nFax: +1 956 997 9231","truncated":false,"body_characters":5483}