Inadequate System Monitoring/Oversight

A fire occurred in a hydrogen storage facility. The fire was reported by an employee who saw the fire start after he had aligned valves at the hydrogen storage facility in preparation for putting the hydrogen injection system into service. The employee escaped injury because he was wearing fire-retardant protective clothing and was able to quickly scale a 7-foot-high fence enclosing the hydrogen area. The local fire brigade was dispatched and offsite fire fighting assistance was requested.

Summary
A faulty modification to a multiple-gas piping manifold allowed mixing of hydrogen and oxygen that resulted in a storage tube explosion. Several employees suffered severe burn injuries from the incident.

A hydrogenation experiment was being performed under 60 atm hydrogen, inside a high-pressure reactor cell. The experiment was conducted inside a fume hood and left overnight. The hood caught fire during the night, resulting in fire damage to the fixture, hood, and exhaust duct, as well as water damage to much of the building. Based on the local fire department investigation, the fire started from faulty electrical wiring that was used to provide power for reactor cell heating.

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.

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.

Hydrogen was released near the ground when the vent line from a 13,000-gallon liquid hydrogen storage vessel suffered damage from unusually high winds. The toppled vent line did not shear or tear, but sustained a kink that restricted hydrogen flow and created a back pressure on the vessel relief system.

Repair efforts were hampered by the potential for cold hydrogen gas, a flammability hazard, in the work area. Shut off or redirection of the hydrogen was not possible, and variable breezes made set up of safe zones uncertain. A protocol had not been prepared for this scenario.

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.

The incident occurred in the catalytic hydrotreatment plant of an oil refinery. The plant, which began operations in September 1997, has a capacity of 1650 tons/day of light fuel oil and 1450 tons/day of heavy fuel oil. The plant was designed to desulfurize the light and heavy fuel oil fractions produced in the refinery by treating them with high-pressure hydrogen over a catalyst to remove sulfur (producing hydrogen sulfide as a byproduct).

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.

A distillate dewaxing unit at an oil refinery was undergoing hot hydrogen regeneration of the catalyst when an explosion occurred. Catalyst regeneration is a periodically performed procedure, in which the normal liquid hydrocarbon feed is stopped and a hydrogen-rich gas mixture is fed through the catalyst bed for which the normal operating temperature is raised from 700F to 800F. During the catalyst regeneration process the reactor pressure is increased from normal operating levels just below 600 psig to about 640 psig.