Fluid Transients Ignited the San Bruno Gas Pipeline Explosions

Abstract

Abstract Gas pipeline explosions and deaths occur year after year, and a primary cause for those explosions is now known. For decades, these explosions were attributed to corrosion and other incidental causes, but the extent of pipeline damages cannot be explained by corrosion. Pipelines are obliterated by large explosions, and pipelines explode from the inside to the outside. Pipes cannot explode in this manner unless air is present inside the pipes. To date, all previous investigations assumed that the gas industry prevents all air from entering pipelines, and this question about air was not raised in previous government investigations. Accordingly, explosion causes were not understood. Acknowledging that air is inside pipelines at the time of explosions, the ignition cause can be explained. When fluid transients occur in pipelines, flammable gases compress and heat to explode at the autoignition temperatures of the gases. In natural gas piping, explosions occur at system low points where air collects, since methane (natural gas) is lighter than air; and in propane, ethane, or butane systems, explosions occur at system high points, since these gases are heavier than air. In the absence of this Leishear Explosion Theory, the fact that pipes explode outward cannot be explained. An incorrect claim could be made that the stored energy of methane is so great that the pipes explode, but calculations show that this energy is inadequate to create the large craters created during pipeline explosions. In other words, air is required for internal gas pipeline explosions, fluid transients cause pressures to blow up pipelines, these transients may be caused by sudden valve slams, where slam valves are used to control gas flow in pipelines. To understand the fundamental physics of pipeline explosions, a San Bruno natural gas pipeline explosion will be evaluated as an example of this explosion theory.