A petroleum refinery experienced a catastrophic rupture at one bank of three heat exchangers in a catalytic reformer/naphtha hydrotreater unit because of high temperature hydrogen attack (HTHA). Hydrogen and naphtha at more than 500F were released from the ruptured heat exchanger and ignited, causing an explosion and an intense fire burned for more than three hours.

The rupture fatally injured seven employees working in the immediate vicinity of heat exchanger at the time of the incident. The workers were in the final stages of a start-up activity to put a parallel bank of three heat exchangers back in service following cleaning. Such start-up activities had resulted in frequent leaks and occasional fires in the past and should have been considered as hazardous and nonroutine. view more

Overview: A hydrogen leak and explosion occurred due to the installation of an incorrectly sized gasket at the suction line of a hydrogen compressor in a refinery hydrodesulfurization plant. The incorrectly sized gasket was mounted during the startup of the plant in 2001 and had never being inspected nor replaced.

Incident synopsis: The operating conditions were stable when the operator received an alarm indicating pressure loss in the circuit. He immediately instructed his field personnel to inspect the area. The hydrogen leak was confined inside the compressor room because the walls and roof were not provided with ventilation devices. An explosion occurred, causing two fatalities and the destruction of the compressor room and some of the surrounding area.

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

Forty-six hydrogen cylinders were accidentally charged with air instead of additional hydrogen during recharging operations at a synthetic liquid fuels laboratory. Cylinders were manifolded in batches of 10 or 12 to the utility compressor outside the laboratory. In normal operations, partly used cylinders containing hydrogen at a pressure of 800-900 psi were recharged to a pressure of 2000-2100 psi. Since the contaminated cylinders contained a highly explosive mixture of about 40% hydrogen and 60% air, it was decided to release the compressed gas to the atmosphere outside the building after grounding the cylinders. Two of the cylinders were successfully discharged, but an explosion occurred while the third cylinder was being discharged. Two chemical engineers were killed by the blast, view more