Pipe rupture and fire at a refinery

A series of explosions at an oil refinery reformer unit ,converting low-octane gasoline into high-octane unleaded fuel. The unit was being brought back online after a week of repairs to a compressor. The explosions were caused by a rupture to an 8 inch naphtha and hydrogen feed pipe.
Fire officials cited higher than normal line pressures just before the blast. The ensuing fires were quickly contained and extinguished, but caused offsite traffic within several blocks to be stopped. As a precautionary measure, a second reformer unit was shutdown pending the investigation. A large number of injuries was due to the close proximity of a construction crew working in the area.

The INITIATING CAUSE was the loss of confinement of a pipe carrying naphtha and hydrogen.

The pipe failed at a pressure (55 bar) higher then the its operative value, but still below its design rupture value. This suggest a root causes related to some form of material or component degradation.

Hydrogen, naphtha feed pipe;

The reformer was being brought back on line after being shutdown for several weeks for repairs.

Two of the affected memebrs of the crew were declared dead at the scene. and a further one later in hospital.
Amonge the injured workers, ten people were initially in critical condition, with many suffering severe burns. Several victims were contractors working on the unit during its startup.

The ensuing fires were quickly contained and extinguished, but caused offsite traffic within several blocks to be stopped.