An Australian Transport Safety Bureau examination has discovered that the failure of an improperly installed electrical solenoid valve caused the brief spread of flame from a liquified hydrogen carrier gas combustion unit’s vent stack.
The liquified hydrogen (LH2) carrier Suiso Frontier, constructed as a prototype ship to evaluate the technical issues of transporting LH2 by water, made its maiden voyage on January 20, 2022, and it docked at the Port of Hastings in Victoria.
A further 55 t of LH2 were to be loaded onto the 116-meter ship from the gas liquefaction facility in Hastings before it returned to Kobe, Japan, on December 25, 2021.
The ship was still berthed on January 25, 2022, after LH2 had been loaded at Hastings on January 24, and that night, a problem with the gas control system occurred.
A crew member on board the ship noticed a yellow gas flame briefly spreading from the vent stack of the gas combustion unit on the ship’s deck. No subsequent fire or explosion occurred, and no casualties or property damage were noted.
A gas combustion unit’s air fan discharge damper actuators, which control the amount of air entering the unit, were discovered to be equipped with direct current (DC) electrical solenoid valves that were incompatible with the 230 V alternating current (AC) supply from the GCU control system, according to an ATSB investigation.
The solenoid valves “were subjected to conditions for which they were not designed” throughout the nearly 400 hours of duty previous to the incident, according to ATSB Chief Commissioner Angus Mitchell.
“The fan discharge damper it was controlling closed when one of these solenoid valves malfunctioned. As a result, the gas combustion unit’s temperature rose, finally leading to the release of flame from the vent stack.
The ATSB discovered the gas combustion unit was not equipped to detect the failure of the valve or the subsequent closing of the damper, in addition to the improper solenoid valve being installed.
According to Mr. Mitchell, “automated safety systems intended to identify a failure and avoid such a catastrophe were ineffective.”
The gas combustion unit’s maker, Saacke, installed limit switches on each air fan discharge damper to track the position of the dampers in response to the occurrence.
Additionally, if a fault is found, the unit will be stopped by the system’s control logic.
According to Mr. Mitchell, “The ATSB’s inquiry emphasizes how critical it is to make sure automated shipboard operating systems are outfitted with safety safeguards to prevent hazardous outcomes in the case of a breakdown.”
The incident also highlights the value of strict manufacturer quality controls to guarantee that the right system components are chosen and fitted to equipment.