A high risk alert safety notice has been issued by the Society for Gas as a Marine Fuel (SGMF) after reports of leakages when bunkering LNG.
According to the notice, SGMF has received several reports of leakages from dry-disconnect/connect or quick connect/disconnect couplings used during LNG bunkering operations for 6- and 8-inch nominal diameter bunkering lines.
The notice says that differential movement between supply and receiving bunkering equipment is causing leakages at the coupling sealing face/surface. It is not clear that any design loads are being exceeded whilst the movement is occurring, however it is causing the coupling to leak.
The notice recommends that care needs to be taken to ensure couplings are not overloaded during bunkering operations and that for couplings of six-inch size or larger, the equipment needs to be fully supported throughout the transfer operation.
This can be achieved by using additional support structure around the coupling nozzle and cryogenic hose, however each party should evaluate the best solution depending upon their applications and equipment; straps or clamps might be used instead.
Thermal expansion/contraction should also be considered when structural constraints are placed around the equipment.
Care should also be taken when cryogenic hose movements are restricted, to prevent damages to the hose.
Smaller size dry-disconnect/connect couplings might not require additional support but should be closely monitored during the whole bunkering operation.