A significant hydrogen leak occurred during refueling of the onboard hydrogen storage tank of a fuel cell-powered lift truck while it was completely depowered. The in-tank shutoff solenoid valve had recently been replaced, and this was the initial refueling event after the replacement. The fuel zone access panel was removed to allow constant visual leak checking with Snoop leak-detection fluid. The event occurred during the final pressure testing of the repaired system when an O-ring failed at approximately 4500 psi, releasing the entire contents of the hydrogen tank in about 10 minutes. The dispenser hose/nozzle was immediately disconnected, and the leak location was quickly isolated to the tank/valve interface. A 30-foot boundary around the lift truck was cleared of personnel and view more
One morning a saltwell pump was placed in operation. Operation of this equipment requires that the Standard Hydrogen Monitoring System (SHMS) cabinet be in operation. Later that morning, during the morning surveillance rounds, the Standard Hydrogen Monitoring System (SHMS) cabinet was found not to be in the operational mode.
On the previous day, the night shift saltwell operator assigned to run the saltwell pump had placed the SHMS monitor in operational mode; however, the saltwell system was not started at this time. Shift turnover was conducted and the condition of the SHMS was turned over to the appropriate saltwell operator and shift manager. During the day shift the day shift operator assigned to the complex received approval from the operations engineer to place the SHMS view more
During a facility walk-through, it was noted that a combustible gas (hydrogen) monitoring system installed in a furnace room was inoperable (the system had been unplugged). This system is used to detect and warn facility employees of an explosive or flammable environment. An explosive or flammable environment can only occur if there is a leak in the system, which would not be expected to occur during normal operations. When the system was reactivated, no leaks were indicated.
The incident had the following three causes:
A procedure describing administrative controls necessary to ensure safe operations in the area should have been developed and implemented prior to disabling the hydrogen monitoring system.
The hydrogen monitor was not hard-wired, which allowed it view more
A demolition technician noted an elevated combustible gas lower explosive limit (LEL) on a pipe that was being tested prior to cutting (No. 2 pipe). The No. 2 pipe was one of four pipes being tested. The other three pipes tested less than detectable for combustible hydrogen gas. Testing involves tapping the pipe and connecting the pipe to an Explosive Gas Detector via a tube. When an elevated LEL is identified, the pipe is allowed to vent and then retested prior to cutting. After tapping the No. 2 pipe, the work crew left the pipe open to vent and departed the area for the end of shift.
At approximately 7"45 PM on the same day, a crew was on overtime to support roofing activities. Since additional workers were available, the craft supervisor decided to re-enter the viewing view more