(Reuters) - In the end, all it took was a small chemical spill -- perhaps less than a barrelful -- to bring down the newest, mightiest oil refinery in the United States. 

Three weeks ago, while workers repaired a minor leak at the Port Arthur, Texas plant owned by Motiva Enterprises, a few gallons a day of so-called "caustic" was inadvertently seeping into the newly built crude distillation unit (CDU), the 30-story-high network of interconnected cylinders and latticed pipelines at the heart of the refining process.

While harmless when mixed with crude, the undiluted caustic vaporized into an invisible but devastating agent of corrosion as the chamber heated up to 700 degrees Fahrenheit (370 Celsius); the chemical gas raced through key units, fouled huge heaters and corroded thousands of feet of stainless steel pipe.