Analysis of pipe failure at the Great Plains Coal Gasification Plant

The rupture of a carbon steel elbow in the methanation area of the Great Plains Coal Gasification Plant resulted in a fire and plant shutdown. Failure studies consisted of an on-site inspection and an extensive laboratory examination that included light metallography, X-ray fluorescence, X-ray diffraction, chemical analyses, and electron spectroscopy for chemical analysis. It was concluded that operation of a heat exchanger under off-specification conditions contributed to higher than design temperatures, lower than design pressures, and higher than design concentrations of carbon dioxide and water in the exit line from a condensate separator. Together, these conditions produced high levels of carbonic acid and higher than design velocities resulting in severe corrosion of the carbon steel.