A refinery hydrocracker effluent pipe section ruptured and released a mixture of gases, including hydrogen, which instantly ignited on contact with the air, causing an explosion and a fire. Excessive high temperature, likely in excess of 1400°F (760°C), initiated in one of the reactor beds spread to adjacent beds and raised the temperature and pressure of the effluent piping to the point where it failed. An operator who was checking a field temperature panel at the base of the reactor and trying to diagnose the high-temperature problem was killed. A total of 46 other plant personnel were injured and 13 of these were taken to local hospitals, treated, and released. There were no reported injuries to the public.

Property damage included an 18-inch (46-centimeter) long tear in the view more

Overview
During start-up operation of a high-temperature, high-pressure plant using hydrogen, hydrogen gas leaked from the flange of a heat exchanger and a fire occurred. The leakage occurred for two reasons:

Insufficient tightening torque control was carried out during hot-bolting and an unbalanced force was generated across the bolts.
A temperature rise was induced across the heat exchanger as a result of a revamping activity, during a turnaround shutdown.

Background
Hot-bolting: In equipment and piping that operate at high temperatures, as the temperatures rise, the tightening force decreases, thus re-tightening of bolts is necessary. This work is called hot-bolting. The design conditions of the evaporator where the fire occurred were 2.4 MPaG, view more