{"operation":"document","citation":"14-0072","title":"Federal Motor Carriers Safety Administration (FMCSA) — Hazardous Materials Safety Interpretation","source_type":"guidance","agency":"Pipeline and Hazardous Materials Safety Administration","status":"guidance","official":true,"published_on":"2014-06-05","effective_on":null,"summary":"14-0072 response to Federal Motor Carriers Safety Administration (FMCSA) concerning 173.22, 173.29, 178.345, 180.405, 180.407, 180.413.","machine_formats":{"json":"https://regulus.evalyn.ai/document/phmsa-interpretation-14-0072.json","markdown":"https://regulus.evalyn.ai/document/phmsa-interpretation-14-0072.md"},"app_url":"https://regulus.evalyn.ai/document/phmsa-interpretation-14-0072","source_url":"https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/legacy/interpretations/Interpretation%20Files/2014/140072.pdf","body":"<<<PAGE 1>>>\n\nU.S. Department\nof Transportation\nPipeline and Hazardous\nMaterials Safety\nAdministration\n1200 New Jersey Avenue, SE\nWashington, D.C. 20590\nMr. David Ford\n200 Hardy Ivy Way\nHolly Springs, NC 27540\nJUN 0 5 20\\4\nRef. No. 14-0072\nDear Mr. Ford:\nThis responds to your letter dated March 25, 2014 requesting clarification of the Hazardous\nMaterials Regulations (HMR; 49 CFR Parts 171-180) regarding cargo tanks. Specifically,\nyou seek clarification on venting, purging and inspection requirements for cargo tank motor\nvehicles. Your questions are paraphrased and answered as follows:\nQl. Since§ 178.345-l(i)(2) was revised in a final rule under Docket No. PHMSA-\n2009-0151 (HM-218F; 76 FR 43532) to permit the top vents on Specification DOT\n406, 407 and 412 cargo tank motor vehicles to be plugged, and§ 180.405(c)(2)(ii)\nauthorizes Specification MC 306 cargo tank pressure relief devices and outlets to\nconform to those authorized for a Specification DOT 406 cargo tank, may the top\nvoid vent on an MC 306 cargo tank be plugged and capped, as long as the bottom\nvoid vent is open?\nAI. The answer to your question is yes. On July 20,2011, § 178.345-l(i)(2) was\nrevised in final rule HM-218F because it was determined that requiring an opening\non top of a cargo tank to vent vapors that accumulate in the void space may be\nunsafe. The preamble ofHM-218F states:\n\"In many instances, such as with gasoline, the vapors are heavier\nthan air and it is not necessary to require cargo tanks to be vented to\nthe atmosphere through a vent located near the top centerline. In\naddition, venting voids through the top of a cargo tank may cause\npremature corrosion of the void space as a result of water\npenetration. Allowing the vent to be plugged will also make it easier\nto identify when there is actually a leak in the bulkhead. Hazardous\nmaterials leaking from the drain will cause an obvious stain/dirt\nbuildup that, with the top vent plugged, cannot be a result of water\ndraining from the top vent and must be a leaking bulkhead.\"\nFor this reason, PHMSA revised§ 178.345-1 to clearly indicate that any void area\nwithin the connecting structure of a cargo tank between double bulk heads must be\nvented to the atmosphere through the required drain or through a separate vent.\nTherefore, like Specification DOT 406, 407 and 412 cargo tank motor vehicles, the\ntop void vent on an MC 306 cargo tank may be plugged and capped, provided that\nthe bottom void vent is open.\n\n<<<PAGE 2>>>\n\nQ2. Would a cargo tank be considered to be \"cleaned and purged\" if the dome lids\nare left open to allow the tank to air out?\nA2. For the purposes of the HMR, \"cleaned and purged\" means no residual\nmaterial and no residual vapor remaining in the interior of a packaging. Section\n180.413(a)(2) requires that \"prior to each repair, modification, stretching,\nrebarrelling, or mounting, the cargo tank motor vehicle must be emptied of any\nhazardous material lading.\" In addition, cargo tank motor vehicles used to transport\nflammable or toxic lading must be sufficiently cleaned of residue and purged of\nvapors so any potential hazard is removed, including void spaces between double\nbulkheads, piping and vapor recovery systems.\"\nFurther, as stated in § 173.29, a packaging would be empty when is it sufficiently\ncleaned of residue and purged of vapors to remove any potential hazard. The HMR\ndo not define a specific method of cleaning and purging because methods vary\ndepending on the nature ofthe hazardous material and the type of packaging. It\nshould be noted that ultimately, under§ 173.22, it is the shipper's responsibility to\nproperly classify a hazardous material and this would include classification of a\nresidue of hazardous material.\nQ3. For vacuum loaded cargo tanks withfull opening rear heads,§ 180.407(c)\nrequires a pressure test every two years and an internal inspection every five years;\nhowever, § 180.407(g) requires an external visual inspection and an internal visual\ninspection to be conducted at the same time as the pressure test. Does this mean\nthat the internal visual inspection is required every two years in conjunction with\nthe pressure test?\nA3. The answer to your question is yes. In the scenario you describe, internal\ninspection would be required every two years in conjunction with the pressure test.\nI hope this information is helpful. If you have further questions, please contact this office.\nSincerely,\nRobert Benedict\nChief, Standards Development Branch\nStandards and Rulemaking Division\n\n<<<PAGE 3>>>\n\nU.S. DOT\nPHMSA Office of Hazardous Materials Standards\nAttn: PHH-1 0\nEast Building\n1200 New Jersey Avenue, SE\nWashington, DC 20590-0001\n6' bon nell\n~ 1 so.11o1\n&(go Tanks,\nl L/ ,.00 1~\nMarch 25, 2014\nREQUEST FOR INTERPRETATION\nI am writing with questions on various issues related to cargo tanks.\nMC306 double bulkhead drains\nOver the years, there have been varying interpretations regarding the legality of a plugged\nbulkhead drain on the top of the MC306. Since it is allowed for the DOT400 series now (HM-\n215-F), can the top void vent on a MC306 be plugged or capped, as long as the bottom void\nvent is open?\nAir drying of cargo tanks\nThere is no definition of \"cleaned and purged\" in the HMR. Is the practice of opening the dome\nlids and allowing the cargo tank to \"air out\" to the atmosphere sufficient to meet the definition of\n\"cleaned and purged\" for purposes of the HMR?\nPart 180 Tests/Inspections for Cargo Tanks with Full Opening Rear Heads\nFor cargo tanks designed to be loaded by vacuum with full opening rear heads, Section\n180.407(c) requires an external visual inspection every 6 months; a leakage test every year; a\npressure test every 2 years; and an internal visual inspection every 5 years. However, Section\n180.407(g) requires an external visual inspection and an internal visual inspection to be\nconducted at the same time as the pressure test. Therefore, the internal visual inspection is\neffectively required every 2 years in conjunction with the pressure test, correct?\n\n<<<PAGE 4>>>\n\nI appreciate your attention to this matter.\nDavid Ford\n200 Hardy Ivy Way\nHolly Springs, NC 27540\n919 886 1297","truncated":false,"body_characters":6144}