An offgas system mishap involved two explosions occurring within an interval of about 3 ½ hours. The first offgas explosion was reportedly caused by a welding operation on an air line adjacent to a hydrogen sensor line containing off gas. The welding arc initiated a detonation within the offgas piping. The detonation was contained by the piping system but blew out the water seal at the base of the vent stack.The second hydrogen explosion in this incident occurred in the stack base area. Hydrogen accumulated in the enclosed base area after the water seal had been blown in the first explosion. The stack base metal door was blown off its hinges from the second explosion, and the reinforced concrete stack was also damaged. A plant employee walking by the stack at the time of the explosion view more
A water treatment plant used an electrolytic process to generate sodium hypochlorite (NaOCl) from sodium chloride (NaCl). The strategy of using liquid sodium hypochlorite for disinfecting water instead of gaseous chlorine (CL2) is popular because the liquid is generally safer and falls under fewer OSHA and EPA standards. The further idea of generating the liquid sodium hypochlorite on an as-needed basis and in limited quantities also has certain obvious safety advantages.
One of the disadvantages of the electrolytic process is that hydrogen gas is also created as a byproduct. The hydrogen is supposed to be vented, by design, to the atmosphere before the liquid sodium hypochlorite passes into a holding tank.
For various reasons, in this instance it is believed that the view more
During routine facility maintenance of an automatic battery charging system, 6 of 27 nickel cadmium batteries being reinstalled exploded.
Inadequate work procedures in that a probable cause was ignition of accumulated hydrogen gas by a spark generated during the replacement work, and inadequate ventilation of the battery area; a second probable cause was stopped up vent caps, resulting from contaminated electrolyte, which permitted hydrogen pressure build up to an explosive force in the 6 batteries.
An explosion occurred at a chemical plant in an analysis room containing various analyzer instruments, including a gas chromatograph supplied with hydrogen. A contract operator was performing work to install a new vent line to a benzene analyzer that was part of a group of CO2 analyzers, but separate and unrelated to the gas chromatograph. During the process of this work, a plant supervisor accompanying the contract operator doing the work had an indication of flammable gas present on a portable detector. This was in conflict with the fixed gas detector in the analysis room that was indicating that no flammable gas was present. As a precaution, the plant supervisor immediately cut off the hydrogen supply and, along with the contract operator, began the normal task of determining if view more
Within the International Space Station (ISS) oxygen generator, an increase in differential pressure across a pump supplying return water to a PEM electrolyzer fuel cell stack had persisted over a 4-month period and was approaching the shut-off limit for the system. This decrease in performance was suspected to be caused by water-borne catalyst fines containing platinum black and Teflon®* binder materials, shed by the fuel cell stack, and accumulated within the pump's inlet filter. Maintenance in the field was required.
The system had been designed for factory maintenance, and no contingency had been planned to handle field maintenance for such a circumstance. An initial assessment of hazards for the proposed filter maintenance raised the concern that opening the water line view more
An explosion occurred in a 90-ton-per-day incinerator at a municipal refuse incineration facility. Three workers were seriously burned by high-temperature gas that spouted from the inspection door, and one of them died 10 days later. The accident happened during inspection and repair of the furnace ash chute damper. The workers injected water to remove some blockage, and the water reacted with incinerated aluminum ash to form hydrogen, which caused the explosion.
Workers noticed that the post-combustion zone was full of ash and the ash pusher was not working properly, so they tried to remove the ash from the inspection door with a shovel. They discovered a solid layer of "clinker", which is formed by solidification of molten material such as aluminum. The explosion view more
A hydrogen explosion and fire occurred in the benzene unit of a styrene plant in a large petrochemical complex. The unit was being restarted following a scheduled maintenance shutdown. The explosion followed the release of about 30 kilograms of 700-psig hydrogen gas from a burst flange into a compressor shed. Two men were killed and two others were injured. If it had not been a holiday, the death toll and injuries would probably have been much worse.
The operators were bringing the plant online and increasing the hydrogen circulation pressure. About 10-15 seconds before the explosion, they heard a pop and then a loud hiss of pressure being released within the compressor shed. Witnesses reported seeing a white flash and then a large fireball. The fires burned out in 2-3 minutes, view more
In the fall of 2007, the operations team began a procedure (a written procedure was being followed) to sample the liquid hydrogen (LH2) storage vessels ("tanks"), and associated transfer system. This procedure was being performed to determine the conditions within the system, and if necessary, to purge the system of any excess gaseous hydrogen (GH2) in preparation for reactivation of the system. The system had not been used since 2003.
The LH2 storage system contains two (2) spherical pressure vessels of 225,000 gallons in volume, with a maximum working pressure (MAWP) of 50 psig. Eight-inch transfer piping connects them to the usage point. Operations began with activation of the burnstack for the LH2 storage area. Pneumatic gaseous nitrogen (GN2) systems in the view more
A hydrogen explosion occurred in a university biochemistry laboratory. Four persons were taken to the hospital for injuries. Three of these were treated and released shortly thereafter; the fourth was kept overnight and released the following evening. All of the exterior windows in the laboratory were blown out and there was significant damage within the laboratory. One sprinkler was activated that controlled a fire associated with a compressed hydrogen gas cylinder.
First responders from the local community and the university campus were quickly on the scene. Once the injured were attended to and the site secured, response efforts focused first on assessing potential hazards (electrical, fire, hazardous materials, etc). Campus personnel worked into the night to board up windows view more