A sidewall burst failure of a high-pressure polytetrafluoroethylene-lined hose was experienced. The 4.0-m hose was in service for approximately two years, primarily for 70 MPa fueling of hydrogen at ambient conditions ranging from -40 C to +50 C. The total number of fills during its service life was estimated to be 150. In addition to the high-volume fill events, pressure cycling occurred as part of the routine test procedures and operational protocols. These additional pressure-cycling occurrences were approximated to be 200-250 cycles. During each filling cycle, the hose was allowed to bend during connections, as required by the situation. Failure of the hose occurred while temporarily connected to a gas booster, after 1-2 hours of service at 75 MPa. There were no tight bends in the view more
Two fitting failures were experienced for fueling equipment filling systems. Both fittings were installed in the system thermal chamber experiencing ambient temperatures of -40C to +50C. They were connected in high-pressure lines used for 70MPa hydrogen fueling.
The first fitting, a 0.25-inch NPT hose connection, was in service for approximately one year with no signs of leakage. The failure was noticed when the system was pressurized during a filling sequence. The failure was discovered by an audible hissing noise during leak checking. The system was depressurized and the fitting removed and replaced. The system was re-pressurized with no further leakage.
When attempting to reconnect a second fitting, a double-ferrule high-pressure connection, the fitting in question view more
The subject needle valve was used primarily for manual filling to control the flow rate of hydrogen from storage banks to the 70MPa test system. The valve was installed on the exterior of the thermal chamber in ambient temperatures of -5C to +30C. The gas flowing through the valve was at conditioned temperatures of -40C to +50C. The valve was in service for approximately two years and 400 fill operations.
Failure occurred during a test under an open valve condition. When attempting to close the valve, the turning force increased and the technician was unable to completely close the valve. An upstream ball valve was closed to isolate the flow.
Several parties were involved in hydrogen quality sampling when it was discovered that a hose which was being used in the collection process, connecting two sampling components, was not rated for the pressure to which it was being subjected. Upon discovery, the process was stopped, the hose was removed, and an alternate configuration of the equipment was implemented before carrying on the sampling.
During maintenance on a breakaway fitting, a review of the pressure rating of the adapter fitting connecting the pipe to the breakaway found the adapter to be under rated for the design pressure. While the male straight-thread side of the "standard" fitting was rated to 7700 psig, the female compression-tube end of the same fitting was rated to only 4900 psig. The adapter was replaced with a fitting of increased wall thickness meeting the design pressure rating.
A vehicle fill was initiated by the operator. During the hose pressurization step, a leak was observed at the breakaway fitting. The operator pressed the emergency stop to terminate the fill.
During a 70-MPa fueling, the fueling hose breakaway separated. The separation occurred without any extraneous forces other than the pressure of the gas internal to the fueling hose. Upon investigation, it was determined the pull force set point was incorrectly adjusted. No further issues or actions.
A fueler drove away without disconnecting the fueling hose from the vehicle. The breakaway did not open and the receptacle fitting sheared off the vehicle. Subsequent testing of the breakaway showed that the breakaway operated at 210 lbs, which was above the design value of 133 lbs. The hydrogen contained in the hose between the dispenser shutoff valve and the vehicle check valve was released.
The hydrogen fueling dispenser nozzle could not be completely disconnected from the vehicle after refueling. It was finally disconnected after trying several times. The cover of the nozzle interfered with the disconnection operation. No malfunction of the nozzle was found. It can be easily disconnected when it is withdrawn along its axis. Sometimes misalignment occurred due to the weight of the dispenser hose.
During a refueling event, the operator activated the fueling lever in the wrong sequence. The vehicle filled to proper pressure, but filled faster than normal. Under different circumstances, this could have resulted in overheating of the receiving fuel tank.