The Use of Overpressure Exceedance Curves in Building Siting

摘要

Compliance with the American Petroleum Institute (API) Recommended Practice (RP) 752 hasbecome an industry standard. Design and layout of new facilities can incorporate most of the principlesand spacing requirements presented in API RP 752 with a basic consequence modeling study. Yet manyexisting facilities are finding that a basic consequence modeling study indicates major problems foronsite buildings when evaluating vapor cloud explosion impacts. The worst-case explosion scenarios,and often the “more likely” scenarios, typically show unacceptable overpressure impacts at buildingswithin or near hydrocarbon processing units. API RP 752 does allow the analyst to perform a risk-basedanalysis to evaluate the acceptability of building impacts. One of the most useful forms of a risk-basedstudy is the generation of overpressure exceedance curves. These measures of potential impact to abuilding incorporate a wide range of potential explosion scenarios, and the probability of each of thoseevents. This paper will explore the construction of overpressure exceedance curves for a typicalhydrocarbon processing facility, and will highlight some of the benefits, as well as some of the potentialproblems, of their application.