A hydrogen reformer furnace at a refinery was shutdown for maintenance to remove and cap the inlet and outlet headers of some radiant tubes that had previously developed hot spots and been isolated by externally pinching them off at the inlet. A decision was made to leave steam in the steam-generating circuit during this maintenance operation to prevent freezing. After maintenance was complete, the startup procedure required the furnace to be first heated up to 350°C (662°F) prior to introducing 4136 kPa (600 psig) steam into the radiant tubes. Just after the 4136 kPa (600 psig) startup steam was introduced into the reformer furnace inlet, the control room alarm journal reported an extreme positive pressure spike at the same time a single loud bang was reported by the operations view more

An unplanned shutdown of the hydrogen supply system occurred, affecting the hydrogen furnaces in the plant. The apparent cause was an inadvertent valve closing, which was contrary to the written procedure.

A preventative maintenance activity was being conducted on the hydrogen gas system. Shortly after starting that work, various hydrogen gas users notified the emergency response personnel that the hydrogen supply safety alarms sounded, indicating an interruption of the hydrogen gas supply. As a result, the hydrogen furnaces shut down. This shut down is an automated process which injects an inert gas (nitrogen or argon) to prevent the introduction of oxygen and its mixing with any hydrogen gas. All shut downs functioned as designed. As a precautionary measure, fire protection view more