The Esso Longford gas explosion was a catastrophic industrial accident which occurred at the Esso natural gas plant at Longford in the Australian state of Victoria's Gippsland region. On 25 September 1998, an explosion took place at the plant, killing two workers and injuring eight. Gas supplies to the state of Victoria were severely affected for two weeks. Context In 1998, the Longford gas plant was owned by a joint partnership between Esso and BHP. Esso was responsible for the operation of the plant. Esso was a wholly owned subsidiary of US based company Exxon, which has since merged with Mobil, becoming ExxonMobil. Built in 1969, the plant at Longford is the onshore receiving point for oil and natural gas output from production platforms in Bass Strait. The Longford Gas Plant Complex consists of three gas processing plants and one crude oil stabilisation plant. It was the primary provider of natural gas to Victoria, and provided some supply to New South Wales. Normal processing procedure The feed from the Bass Strait platforms consists of liquid and gaseous hydrocarbons, water and hydrogen sulfide (H2S). The water and H2S are removed before reaching the plant, leaving a hydrocarbon stream to be the feed to Gas Plant 1. This stream contained both gaseous and liquid components. The liquid component was known as "condensate". The liquefied petroleum gas (LPG) is further extracted by means of a shell and tube heat exchanger, in which heated "lean oil" and cold "rich oil" (oil which has absorbed LPG) are pumped into the exchanger, cooling the lean oil and heating the rich oil. Explosion at Longford During the morning of Friday 25 September 1998, a pump supplying heated lean oil to heat exchanger GP905 in Gas Plant No. 1 went offline for four hours, due to an increase in flow from the Marlin Gas Field which caused an overflow of condensate in the absorber. (The plant was complex and the hot oil pump was only one component involved in the accident process; why the pump shut down is complicated and important.) A heat exchanger is a vessel that allows the transfer of heat from a hot stream to a cold stream, and so does not operate at a single temperature, but experiences a range of temperatures throughout the vessel. Temperatures throughout GP905 normally ranged from . Investigators estimated that, due to the failure of the lean oil pump,