Safety in Design

9 Gas Explosions

9.1 Introduction

Two types of gas explosions are treated in this chapter. The first category includes gases formed from flashing inflammable liquids when their container collapses. Flashing liquids are liquids that, when stored under pressure, start to evaporate spontaneously when exposed to the atmosphere. The explosions of this category can be particularly violent because large quantities of material can be mixed with air in a short time. A well‐known type of explosion in this category is the BLEVE (boiling liquid expanding vapor explosion). Sections 9.2–9.7 deal with flashing inflammable liquids. The second category concerns the leaking of an inflammable gas into the atmosphere or into an enclosed space. That can occur when, e.g. a natural gas line is damaged. A substantial gas flow into the atmosphere can be dangerous. Even a relatively small gas flow leaking into an enclosed space can be dangerous because it is possible to obtain an explosive gaseous mixture. An example of the latter type of accident is discussed in Section 9.8.

Generally, accidents caused by flashing inflammable liquids are more serious than those by gas leakages.

9.2 Flashing Inflammable Liquids

The accidents described in Sections 9.3–9.7 occurred with flashing inflammable liquids. Those liquids are particularly hazardous materials, and this aspect is dealt with in this section. An accident in which such a liquid was involved is described in Section 1.4. The liquid is LPG ...