In the news yesterday, the ExxonMobil refinery in Beaumont, TX was the scene of a fire where 12 plant workers were injured, with most suffering extensive burns.
The fire occurred near a hydrotreater heat exchanger and the workers were welding a section of the heat exchanger as part of maintenance work at the refinery. The hydrotreater is where harmful substances are removed from the motor fuels so that it can comply with federal law. It uses the highly flammable gas hydrogen, which is under pressure to complete this process. This part of the refinery was shut down at the time of the fire.
This is not the first fire or explosion near a hydrotreater. Tesoro experienced a similar incident in 2010 where seven people died as a result of the incident.