Technical Reports

Vent and Burn Method of Field Product Removal

  • 01
  • May
  • 1994
AUTHOR: Edward S. Parker, Henry L. Cox, Britto R. Rajkumar
SUBJECT: Hazardous Materials
KEYWORDS: Emergency Response, Tank Cars, Derailment, Explosives, Shaped Charges
ABSTRACT: The Federal Railroad Administration tasked the Association of American Railroads, Transportation Test Center Hazardous Materials Training Center, to research and develop safe, reliable operating procedures for of the Vent and Bum method of field product removal, and to define when or if this procedure should be used in the event of tank car derailments involving hazardous materials. The Vent and Bum procedure uses explosive charges to cut holes in the damaged tank car to relieve internal vapor pressure and subsequently drain the liquid product from the car for destruction. Vent and B urn is inherently dangerous and other methods of field product removal or car rerailment must be considered first. This procedure is applicable to some compressed gases and some flammable or combustible liquids shipped in pressure or general service tank cars. Testing was performed both on a sample tank car head and on four full scale DOT 112T340W tank cars. Combinations of jacketing, insulation, and thermal protection materials were explosively cut on the sample tank head to determine procedures to gain access to the tank shell of a jacketed car. Tests on full scale, unjacketed tank cars varied internal tank pressure and liquid fill levels to represent expected lading conditions. The full scale tank cars were explosively cut both on bare steel and through spray-on thermal protection. The scope of this program included the following: Definition of the field application of the Vent and Bum procedure through quantified testing of sample materials and full scale tank cars; Selection of shaped explosive charges that successfully and repeatably cut target tank car and jacketing materials; Specification of explosive charge sizing and application locations; Determination of explosive charge orientation, charge mounting, and charge continuity for cutting success; and Modeling tank car internal pressure release and liquid drainage to determine expected discharge times.