CHARACTERIZING TRANSPORT RISKS

SwRI has received a two-year, $650,000 contract from the U.S. Department of Transportation to study the transport risks associated with gases dissolved in hazardous liquids.

The federal government has well-defined quantitative criteria and regulations for distinguishing hazardous liquids and gases as well as their transport.

“The regulations related to the transportation of hazardous chemicals such as crude oil or gasoline are very different from those for transporting milk,” said Dr. Swanand Bhagwat, a fluids engineer leading the project. “However, the DOT lacks regulatory language to classify the liquids containing significant quantities of dissolved gases. Current regulations do not provide guidelines on how much gas can be dissolved in liquid without changing the hazard classification of the fluid.”

The regulatory gap makes it difficult to determine how to handle and ship the fluids as well as address compliance issues. The presence of gases such as methane and ethane in crude oil or dissolved air in fuels such as diesel and kerosene could increase the vapor pressure and the volatility of the liquids.

“To safely handle hazardous liquids containing dissolved gases, it is necessary to understand the acceptable thresholds,“ Bhagwat said. “It is difficult to estimate the risk of leaks associated with pressurization as well as fire or explosion hazards of ignitable mixtures in a shipping tank.”

Bhagwat is collaborating with SwRI’s Chemistry and Chemical Engineering Division to conduct experiments to ascertain the solubility of gases often found in hazardous liquids transported by rail. The team will then use computer modeling to characterize associated safety risks and hazards. Additional experiments will determine how the concentration of dissolved gas affects the hazardous properties of the liquid and identify how temperature changes and agitation associated with transport affect risks. Experiments will also assess risk associated with venting or leaking vapors of various gases exuded from liquids.