{"operation":"document","citation":"98-0568","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":"1993-06-23","effective_on":null,"summary":"98-0568 response to Truck Trailer Manufacturers Association concerning 178.345.","machine_formats":{"json":"https://regulus.evalyn.ai/document/phmsa-interpretation-98-0568.json","markdown":"https://regulus.evalyn.ai/document/phmsa-interpretation-98-0568.md"},"app_url":"https://regulus.evalyn.ai/document/phmsa-interpretation-98-0568","source_url":"https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/legacy/interpretations/Interpretation%20Files/1998/980568.pdf","body":"<<<PAGE 1>>>\n\n1\nof Transportation\nU.S. Department\nWashington, D C\n400 Seventh Street, S.W.\n20590\nJUN 23 1993\nALice.s.\nMr. Donald W. Vierimaa\nVice President-Engineering\nTruck Trailer Manufacturers Association\n1020 Princess Street\nAlexandria, VA 22314\nDear Mr. Vierimaa:\nThis is in response to your letter concerning rollover protection requirements for a specification\nDOT 406 cargo tank. Specifically, you asked if a manufacturer, who uses two full length parallel\noverturn protection rails (inverted V rails), can design the rails so that each withstands one-half of\nthe loads specified in 49 CFR 178.345-8(c)(1).\nThe answer is no. In the case of inverted V rails that run along each side of the top of the cargo tank\n(not in the center), a rollover will cause a sudden impact of the ground with only one of the rails,\nthen, if and when the tank rolls to 180 degrees, which seldom occurs, the second rail comes into\n:\ncontact with the ground and experiences a different kind of loading. Then, if the tank continues to\nroll, the first railing will be suddenly released of all loading and the total load will shift entirely to\nthe second rail. In such a rollover scenario, it is not reasonable for a designer to distribute the\nrequired loading between the two railings.\nHowever, a designer could provide for two inverted V railings to share the distribution of the\ntransverse loading, by providing for transverse bracing to connect the two railings and to treat the\nentire design as a single device for the purpose of handling the transverse loading. Without\ntransverse bracing, inverted V railings should be considered separate non-load-sharing devices.\nOther devices, such as \"tombstones\" are considered load sharing devices and are symetrically located\nalong the centerline of the top of the cargo tank, so that in a normal overturn scenario, the devices\nstrike the ground simultaneously and each device receives a sudden loading of similar magnitude.\nIn such a case, it is reasonable to distribute the required design loading among all the devices.\n--\n\n<<<PAGE 2>>>\n\n2\nIf you need further assistance, please contact us.\nSincerely,\nThe\n#. Allan\nThomas G. Allan\nSenior Transportation Regulations Specialist\nOffice of Hazardous Materials Standards\n\n<<<PAGE 3>>>\n\n- i\nFlle: 178,345-8\nSCi\n333\n,310\nTruck Trailer Manufacturers Association\nTANK CONFERENCE\n1020. Princess Street, Alexandria, VA 22314\n703-549-3010 Fax: 703-549-3014\nRichard P. Bowling, President\nJanuary 15, 1997\nEdward T. Mazzullo\nDirector\nOffice of Hazardous Materials Standards\nResearch & Special Programs Administration\nU.S. Department of Transportation\n400 Seventh Street, S.W.\nWashington, D.C. 20590\nSubject: Request for an Interpretation of Rollover Protection\nof 178.345-8(c)(1)\nDear Mr. Mazzullo:\nTypically, two full length parallel overturn protection rails are installed on DOT 406\ncargo tanks. It each of these overturn rails is designed to withstand one-half of the loads\nspecified in 178.345-8(c)(1), will the pair of overturn rails comply with 178.345-8(c)(1)?\nSincerely,\nDonald W. Vienned\nDonald W. Vierimaa\nDWV/mm\nVice President-Engineering\nCC:\nStephen Keppler\nOffice of Motor Carriers, HSA-10\nNo, Each ra. / inus be\n-\nFederal Highway Administration\nTank Conference Engineering Committee\nts. in\nThe\n•A.\nPats","truncated":false,"body_characters":3285}