Accidental leakages of liquefied propane from high-pressure pipelines may occur despite the use of sophisticated safety equipment and following strict monitoring procedures. Environmental impact of steady and transient leakages were considered from toxicity and flammability viewpoints for two specific scenarios of full pipe ruptures. For each case, calculated mass flow rate, velocity, and temperature of leaking gas were utilized in an EPA-based dispersion model to predict the ground level concentration profiles in the downwind and crosswind directions. For the specific pipeline conditions considered here, the first scenario of a nonjet release (a cloud) produced steady toxic and flammable zones which were about 20 times bigger than those produced in the transient case. The second scenario of a free vertical jet resulted in the formation of a flammable vertical plume, while at ground level it did not produce flammable nor toxic zones. A parametric study of the first scenario confirmed the expected effects of both the gas release time and the atmospheric stability on the size of the dangerous zones. Within the typical range, the wind speed was found to have opposite effects for steady and transient releases. For a steady release, the dangerous zone was wider for slower winds and vice versa for a transient case. Moreover, the size of the dangerous zone was found to be an exponential function of the pipe diameter, while the effect of the initial pipe pressure was insignificant.

Badr, O., and El-Sheikh, H., 1993, “Environmental Hazards due to Rupture of Natural Gas Pipelines,” Final Report to UAE University Research Council.
Gubaidullin, D. A., et al., 1986, “Nonsteady Discharge of Liquefied Hydrocarbons in The Rupture of Pipelines,” High Temperature (English transl. of Teplofiz Vys Temp), Vol. 24, No. 2.
Haffar, W., 1992, “Draft ADNOC Environmental And Occupational Health Guidelines,” a report issued by Abu Dhabi National Oil Company, United Arab Emirates, p. 8.
Havens, J. A., and Spicer, T. O., 1985, “Development of an Atmospheric Dispersion Model for Heavier-than-Air Gas Mixtures,” Final Report to U.S. Coast Guard, CG-D-23-85, USCG, Washington, DC.
Lihn, M., and Woods, T., 1992, “Long Term Trends in U.S. Gas Transportation,” a report published by the U.S. Gas Research Institute.
Ooms, G., Mahien, A. P., and Zelis, F., 1974, “The Plume Path of Vent Gases Heavier than Air,” First International Symposium on Loss Prevention and Safety Promotion in the Process Industries, ed., C. H. Buschman, El Sevier Press.
Spicer, T., and Havens, J., 1989, User’s Guide for the Dense Gas Dispersion Model, U.S. Environmental Protection Agency, EPA-450/4-89-019.
Turner, D. B., 1970, “Workbook of Atmospheric Dispersion Estimates,” AP-26, Office of Air Programs, U.S. EPA.
White, F., 1991, Viscous Fluid Flow, McGraw-Hill Book Company, New York, NY.
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