ENVIRONMENTAL HAZARDS DUE TO RUPTURE OF A LIQUEFIED PROPANE PIPELINE

Accidental leakages of liquefied propane from high-pressure pipelines may occur despite the use of sophisticated safety equipment and follow ing strict monitoring procedures. Environmental impact of steady and t ransient leakages were considered from toxicity and flammability viewp oints for two specific scenarios of full pipe ruptures. For each case, calculated mass flow rate, velocity and temperature of leaking gas we re utilized in an EPA-based dispersion model to predict the ground lev el concentration profiles in the downwind and crosswind directions. Fo r the specific pipeline conditions considered here, the first scenario of a nonjet release (a cloud) produced steady toxic and flammable zon es which were about 20 times bigger than those produced in the transie nt case. The second scenario of a free vertical jet resulted in the fo rmation of a flammable vertical plume, while at ground level it did no t produce flammable nor toxic zones. A parametric study of the first s cenario confirmed the expected effects of both the gas release rime an d 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 exponentia l function of the pipe diameter, while the effect of the initial pipe pressure was insignificant.