A partial pressure sensor for an automated gas environment system (AGES) was not functioning correctly for pure hydrogen flow. While personnel were troubleshooting the problem, a burst disk ruptured resulting in a leak of hydrogen gas and actuation of a flammable gas alarm.

System troubleshooting involved the installation of a small hydrogen gas cylinder and temporary manual valve in an engineered ventilated enclosure adjacent to an instrument sample well. A burst disk associated with the temporary manual valve ruptured upon opening of the gas cylinder valve. The vented gas, exhausting through an engineered exhaust system, triggered the flammable gas detector. Personnel promptly evacuated the area in accordance with established procedures. Appropriate personnel responded to the view more

A pressure relief device (frangible burst disk) on one of a hydrogen delivery tube trailer's 26 tubes failed prematurely and released hydrogen while filling a hydrogen storage tank at a government facility (see Attachment 1). Prior to the filling process, all procedures and safety checks, including connection to the facility's regulator/distribution control system with leak checking and follow-up verification of leak checking by facility personnel, were completed (see Attachment 2 for more details). During the filling process, a person walking near the facility heard the noise of escaping gas that included occasional popping sounds typical of bursts of gas release. Facility personnel were alerted and the tube trailer vendor's incident response team was dispatched to the view more

A 9,000-gallon (34,069-liter) cryogenic liquid hydrogen storage vessel, installed outdoors at a manufacturing plant in an urban area, over-pressurized and released hydrogen into the atmosphere through a safety relief device (burst disk). When the burst disk released pressure, a loud bang was heard by neighbors and reported to the local police. The police investigated and heard the sound of gaseous hydrogen escaping from the vessel's vent stack, which rose approximately 15-20 feet (4.6-6.1 meters) in the air.

Police called the local fire department. Firefighters entered the facility and told employees inside that there was an explosion on the property and they needed to evacuate. As a precautionary measure, some nearby city buildings were also evacuated and the street was view more

The malfunctioning of the non-return valve of the hydrogen compressor caused the pressure between the hydrogen bottle and the compressor to rise up to the maximum allowed pressure of 275 barg. As a consequence, as foreseen by the safety system, the rupture disk of the safety valve broke and the hydrogen content of the gas bottle and the pipe section involved was released on top of the building. The flame was seen for a very short period by a guard, and could have been caused by the following series of events:

Expansion of hydrogen at the end of the exhaust pipe.
Consequent mixing of hydrogen and air up to a near-stoichiometric mixture and increase of gas temperature.
Mixture ignition due to sparks from static electricity generated by gas molecule friction against view more

A 2000-psia-rated gas cylinder (nominal size 10"x1 1/2") was being filled with hydrogen to a target pressure of 1500 psia. The cylinder suffered a failure at an indicated pressure of 1500 psia during filling. Investigation of the failure subsequently revealed that a faulty digital readout had allowed the cylinder to be over-pressurized. There were no safety consequences due to the failure and no damage to the facility or equipment. The cylinder was being filled in a test vault that was specially designed for the high-pressure burst testing of pressure vessels and components. While no over-pressure cylinders were released from the laboratory for use, this incident is being reported to address the potential and subsequent lessons learned.

Investigations revealed that the view more