Report Detail:

Australian oil and gas producer Santos says a rare chemical reaction between mercury and aluminium caused the gas leak which contributed to the fire at its Moomba plant this year. Investigations into the fire are continuing with final finding some weeks away, Santos said. Meanwhile, findings from an initial independent metallurgical laboratory study commissioned by Santos and based on samples taken from the affected area of the plant, have confirmed that a failure of the inlet nozzle in the plant's heat exchanger was the cause of the gas release which led to the fire, the company said.

The failure was because of liquid metal embrittlement (LME) of a cold box by elemental mercury. Minute levels of mercury are found in natural gas from underground reservoirs in Australia and south-east Asia. LME occurs when the mercury reacts with the aluminium pipes causing the metal to become brittle and in this case resulting in a crack on the nozzle which leaked gas, Santos said.

LME is a rare instantaneous phenomenon that occurs without warning. "The Moomba incident is the first known occurrence of a gas release and fire due to LME," a Santos spokesman said. The company said further investigations would take a closer look at the cold box to determine if any other factors may have contributed to the incident.

These investigations are expected to take some weeks to be completed, it said. The Santos spokesman said that in the meantime Santos was changing its process to remove mercury from the gas before the final stage of the cooling process. "The LME is a rare phenomenon that is not related to maintenance or operating processes," he said. "At the same time we want to make sure it doesn't happen again."

Santos said insurance which covers it for damage by fire were aware of LME and the issue of elemental mercury in the gas. The claim is being progressed

Reported in The Age - March 8th 2004