The Transportation of Dangerous Goods (TDG) Directorate of Transport Canada (TC) is the focal point for the national program to promote public safety during the transportation of dangerous goods. The TDG Directorate serves as the major source of regulatory development, information, and guidance on dangerous goods transport for the public, industry, and government employees in Canada . The Safety Research and Analysis branch of the TDG Directorate supports this mandate by studying various aspects of the transportation system to inform decision-making processes.
The TDG Directorate is undertaking a project to consider possible improvements to the current BLEVE table found in the Emergency Response Guidebook (ERG), to support the work of the Canadian Transport Emergency Centre (CANUTEC). CANUTEC is a national advisory service that assists emergency response personnel in handling dangerous goods emergencies, 24 hours per day, 7 days a week. The ERG is produced by Transport Canada, the US Department of Transportation (DOT), and the Secretariat of Infrastructures, Communications and Transport of Mexico (SICT), with help from the Centro de Informaciòn Quìmica para Emergencias (CIQUIME) of Argentina. The ERG is available in English, French, and Spanish, in various formats, on the CANUTEC website (Information about the ERG, including the most up-to-date PDF versions for download can be found here: https://tc.canada.ca/en/dangerous-goods/canutec/emerg…).
A BLEVE is defined as an event where a container holding a pressure-liquefied gas fails catastrophically followed by the explosive release of boiling liquid and expanding vapour. The BLEVE is a physical explosion where the hazards include blast and projectiles. If the commodity is flammable, then a fireball and thermal radiation may also result, if the released cloud is immediately ignited. This is usually the case if the container failure is caused by fire impingement. If a flammable cloud is not ignited immediately, then delayed ignition could lead to other fires, explosions, etc., away from the location of BLEVE initiation. If the commodity and resulting cloud are toxic and/or corrosive, then these too become possible threats.
To provide updated emergency response advice for use in TDG incidents, the TDG Directorate requires the services of a contractor to perform a search and review of scientific literature, previously completed tests and/or models and/or past incidents involving a BLEVE of pressure-liquefied gases, as well as subsequent analysis.
The objective of the project is to assess scientific literature and data from previously completed tests and/or models pertaining to BLEVEs applicable to means of containment currently used in Canada, the United States, and Mexico, as well as past BLEVE incident data, to:
- Identify the pressure-liquefied gases that have been involved in past BLEVE events. NOTE: Do not include events resulting in explosions from a vapour cloud with a concentration that is within the flammable range for that gas, that is confined inside a structure, and that is ignited (also known as vapour cloud explosions (VCE) (i.e., where the means of containment was not previously flame impinged leading to the rupture));
- Develop a more detailed, substance-specific listing of the hazards and consequences of a BLEVE, to improve emergency response guidance in the ERG;
- For each identified substance with BLEVE potential, perform an evaluation of the appropriateness and effectiveness of the recommended distances in the “BLEVE – Safety Precautions” section of the ERG in protecting emergency response personnel and the public from their identified hazards when involved in a BLEVE based on previously completed tests and/or models and/or past incidents involving the substance (i.e. of whether or not the current distances would be adequate);
- Suggest possible modifications to the “BLEVE – Safety Precautions” section of the ERG based on any updated or new information with supporting rationale; and
- Suggest criteria for choosing between the tactics of shelter-in-place vs. evacuation during BLEVE events.
