During normal operations, a two-inch flame was discovered emanating from a pinhole leak in a hydrogen line at an aircraft parts manufacturing facility. Hydrogen was not in use by any process in the facility at the time. The flame was discovered by a contractor who was about to start welding on scaffolding about 3-5 feet away. Before starting, the welder searched the immediate area for any signs of fire per his training. When he spotted the flame, he called his supervisor.
An operator tried to put out the fire with a fire extinguisher, which resulted in the flame enlarging by one inch. All employees and contractors were instructed to leave the area, and the EHS team leader called 911 and informed the fire department that there was a hydrogen fire at the facility. She then put an evacuation call out over the public address system. The administrative assistant hit the fire alarm on her way out of the office and went to the evacuation area. Then the operators began the process of shutting down the five furnaces that were online.
The EHS team leader met the fire department and advised them of the fire. They began blocking the street and preparing to enter the building. The decision was made to close the hydrogen valves. Plant personnel and two firefighters proceeded to the hydrogen tank to close the valves. The firefighters asked about the routing of the hydrogen line, the status of hydrogen tank valves, and the likelihood that the fire could spread to the nearby gas feed shelter containing the hazardous chemicals and the other flammable gas lines. It was determined to be highly unlikely that the fire would reach the gas feed shelter, so the firefighters decided to allow the fire to burn out. There was approximately 100 feet of line from the tank to the location of the fire. After 30 minutes, the fire was still burning.
The EHS team leader contacted the hydrogen supplier to ensure that the hydrogen tank was shut down properly. The hydrogen supplier's technical phone support also advised that it might require an extended length of time for the pressure in the line to drop enough for the fire to go out. This information was communicated to the firefighters. The hydrogen supplier also dispatched a technician to the site. When the technician arrived, he and the maintenance team leader walked through the emergency shut-down procedure for the hydrogen tank.
An operator and a firefighter, both wearing PPE and breathing gear, went back into the area of the fire to check if all equipment was properly turned off. They verified via the plant control system that everything was shut down. The firefighter checked the fire and verified that it had burned out. Plant personnel were then allowed to re-enter the facility.
Replace the existing copper and carbon steel hydrogen pipeline with ¾-inch schedule 40 stainless steel.
Reroute the new hydrogen line in the preferred location.
Locate new hydrogen shut-off valves in a more convenient location.
Remove all abandoned underground hydrogen lines.
Continue to confer with the local fire department on the new piping system design until the project is completed.