{"operation":"document","citation":"05-0212","title":"Truck Trailer Manufacturers Association — Hazardous Materials Safety Interpretation","source_type":"guidance","agency":"Pipeline and Hazardous Materials Safety Administration","status":"guidance","official":true,"published_on":"2005-10-28","effective_on":null,"summary":"05-0212 response to Truck Trailer Manufacturers Association concerning 178.345.","machine_formats":{"json":"https://regulus.evalyn.ai/document/phmsa-interpretation-05-0212.json","markdown":"https://regulus.evalyn.ai/document/phmsa-interpretation-05-0212.md"},"app_url":"https://regulus.evalyn.ai/document/phmsa-interpretation-05-0212","source_url":"https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/legacy/interpretations/Interpretation%20Files/2005/050212.pdf","body":"<<<PAGE 1>>>\n\nof Transportation\nU.S. Department\nOCT 28 2005\nWashington, D.C. 20590\n400 Seventh Street, S.W.\nPipeline and\nHazardous Materials Safety\nAdministration\nMr. Jeff Sims\nRef. No. 05-0212\nTTMA Engineering Manger\nTruck Trailer Manufacturers Association\n1020 Princess Street\nAlexandria, VA 22314-2247\nDear Mr. Sims:\nThis is in response to your letter dated September 2, 2005 concerning a letter issued on,\nApril 7, 2004 (Ref No.: 04-0055) that retracted a letter issued on, September 25, 2003\n(Ref No.: 02-0287). The retracted letter permitted the vent on top of a cargo tank at the\ndouble bulkhead to be plugged, provided the drain was left open. Specifically, you\nrequest that we reinstate the September 25, 2003 letter, to permit vents to remain\nplugged.\nThe purpose of the vent in question is to allow vapors to escape to the atmosphere. The\nphysical properties of gasoline vapors prohibit venting through the drain at the bottom of\nthe tank because gasoline vapors, like most vapors, are lighter than air and will rise to the\ntop of the tank. To provide adequate ventilation and drainage, the cargo tank must be\nvented to the atmosphere and the bottom drain must be kept open at all times (see\n§ 178.345-1(i)(2)). Therefore, based on the requirement in § 178.345-1(i)(2), we are not\nreinstating the September 25, 2003 letter.\nI hope this information is helpful. Please contact us if you require additional assistance.\nSincerely,\n178.345-1\n050212\n\n<<<PAGE 2>>>\n\nTANK CONFERENCE\nTIMA\n1020 Princess Street • Alexandria, Virginia 22314-2247 • (703) 549-3010 • Fax (703) 549-3014\nTruck Trailer Manufacturers Association\nSuplo\nRichard P. Bowling\nPresident\nSeptember 2, 2005\n5178: 345-1\nJohn A. Gale\nChief, Standards Development\nOffice of Hazardous Materials Standards DHM-10\nCargo Tanks\nPipeline and Hazardous Materials Safety Administration\n05-0212\n400 Seventh Street SW\nU.S. Department of Transportation\nWashington, DC 20590\nDear Mr. Gale;\nTTMA is an international trade association comprised of truck trailer and tank trailer manufacturers,\nalong with cargo container, cargo tanks for trucks and container chassis manufacturers. The associate\nmembership represents material and component suppliers to the industry.\nwith Ref. No. 04-0055 suggesting that,\nWin Rer. e: 04- considerating that, bothpreadip vent an byotr drainment dae kept pen 014\nissue is whether the top \"Inspection/Maintenance Opening\" on any MC-300 or DOT -400 series cargo\ntank must be open at all times because someone perceives this opening to be a \"vent.\" The industry\ndoes not define these plugged nozzles as vents (obviously because they are plugged). They are a totally\nunregulated nozzle installed on the void to assist in pressure testing the void area to locate possible leaks\nin the bulkhead or failures in the connecting structure itself. There is actually a large quantity of cargo\ntanks that do not have a top opening in the cargo tank void at all. Instead, they have two openings near\nthe bottom. There is nothing in the regulation that would indicate this practice is illegal.\n49 CFR 178.345-1(i)(2) defines the vent and drain in between double bulkheads as follows:\n\"Any void within the connecting structure must be vented to the atmosphere and have a drain located on\nvoid within the connecting structure of a carbon steel, self-supporting cargo tank may be either a single\nthe bottom centerline. Each drain must be accessible and must be kept open at all times. The drain in any\none of which is located on the bottom centerline.\"\ndrain of at least 1.0 inch diameter, or two or more drains of at least 0.5 inch diameter, 6.0 inches apart,\nReviewing this paragraph of the regulation;\n1) VENT SIZE - The size of the vent is never defined. The vent could be a pinhole drilled\n2) VENT LOCATION - The location of the vent is not defined. There is no mention in this\nthrough the connecting structure.\nparagraph that the vent must be located on top centerline.\n3) VENTED TO THE ATMOSPHERE - The interpretation indicates that vents are\n\"normally\" located at top centerline of the tank and that they are required to communicate\nwith the vapor space. We believe you are referring to the \"Pressure Relief\" requirements of\n\n<<<PAGE 3>>>\n\nTTMA Petition for Reconsideration\n2\nany location would communicate with the vapor space.\n178.345-10. The connecting structure does not carry product and therefore any opening at\nEACH DRAIN MUST BE KEPT OPEN AT ALL TIMES - The interpretation indicates,\n\"...if the bottom drain were closed or plugged ...\" This would be a violation of the\nregulation.\nMOISTURE IN THE VOID MAY BE A SOURCE FOR CORROSION • The comment,\n...moisture entering through the top vent will be trapped and become a source of corrosion,\"\nis contradictory to the premise of the interpretation. If the opening at the top of the void is\nplugged as is the typical industry practice, it would be nearly impossible for moisture to enter\nthe void.\n6) VAPORS WILL HAVE NO MEANS TO ESCAPE IF THE VENT IS PLUGGED - not\nextremely dangerous situation. Cargo tanks are typically filled with vapors when empty\nventing vapors which may have accumulated in the void space does not cause some type of\nunless they have been recently cleaned. This is a normal occurrence and is not considered an\nextreme hazard within the industry. Quite to the contrary, EPA tends to frown on venting\nvapors to the atmosphere.\n7) DRAIN SIZE - other than self supported cargo tanks constructed of carbon steel, there is no\nrequirement for the size of a void drain.\n8) COMBINED VENT and DRAIN - Nowhere in the regulation does it indicate that the vent\nand drain can not be combined as one opening.\n9) USE OF A HAT DEVICE IS PERMISSIBLE - We can only imagine that the perception\nis that water and debris enter vertically as the trailer is at rest. Cargo tanks do not typically\ngenerate income at rest. Income is generated when they are transporting product 55-75 MPH\ndown the highway. A hat shaped device will not prevent moisture from entering the void\nwith these wind speeds. Depending on the orientation and design of a hat device, even more\nmoisture and debris may be \"directed\" into the void with a hat device.\n10) TRIP HAZARDS - The proposed Hat Device or any other vented cap will create an\nadditional risk of serious bodily injury if someone inadvertently trips on the device while on\ntop of the tank.\nNearly all multi-compartment MC-300 series tank trailers manufactured for over 30 years and DOT-400\nseries tank trailers manufactured for over 10 years have been manufactured with the top\ninspection/maintenance opening plugged. In all of the years that these units have been manufactured,\nand with tens-of-thousands of these units on the highway, and with the hundreds-of-millions of miles\nthat these units have traveled there is no evidence of a plugged top void opening known to be the cause\nof an accident. In the case of carbon steel tank's, allowing any moisture in the void space is going to\nincrease corrosion and is more detrimental to the void space integrity than is being suggested in the\ninterpretation, potentially decreasing the safety of these vessels. TTMA asks that DOT reconsider this\ninterpretation and declare it void as there is not a defined DOT size or location requirement for this\nopening, the interpretation provides no additional safety to the industry and the addition of a hat device\nSincerely;\nJeff Sims\nJeff Sims\nTTMA Engineering Manager","truncated":false,"body_characters":7426}