This is a time of year that myself and other colleagues here at GasBuddy cite refinery maintenance for the reason of rising prices. Many don't always understand how significant this work is. An explosion in 2009 resulted from lack of maintenance at the Silver Eagle Refinery in Utah, when a thinned pipe failed, and resulted in an explosion.
Here's the release from the CSB:
A massive explosion and fire at the Silver Eagle Refinery on November 4, 2009, in Woods Cross, Utah, which damaged homes in a nearby neighborhood, was caused by a rupture in a pipe that had become dangerously thin from corrosion, the U.S. Chemical Safety Board (CSB) reported Thursday. The CSB has released a detailed expert metallurgical report that was commissioned in the course of its ongoing investigation of the incident.
The catastrophic rupture occurred in a ten-inch pipe at the bottom of a reactor in the mobil distillate dewaxing unit. It led to a massive release of hydrogen, which caught fire immediately and exploded, sending a blast wave across the refinery into a subdivision. The blast wave damaged over 100 homes, many with shattered glass. Two of the homes were severely damaged, including one which was displaced off its foundation.