USCG has issued a Safety Alert to raise awareness of potential hazards with insufficiently inspected compressed air cylinders used in lifeboat self-contained air support systems for fire protected lifeboats.
Incident
During a routine inspection of an OCS unit that was unmanned and awaiting decommissioning, company personnel discovered a large hole in one of the facility’s lifeboats. Further examination revealed that a cylinder from the self-contained air support system had ruptured, causing the damage. The rupture sent fragments into the overhead flotation chamber of the lifeboat, and one of the three cylinders was lost to the sea, with its condition unknown. The third cylinder remained in its stowage location but showed signs of severe corrosion.
Many lifeboats with these systems store air cylinders horizontally in or just above the bilge area beneath the centerline seats. Although lifeboat canopies are required to be watertight, water ingress/accummulation in the bilges and cylinder storage compartments can be a common occurrence. The lifeboat involved in this incident was designed with a separate compartment to isolate the cylinders from the bilge, but this compartment was also not watertight and had collected several inches of water. Accessing the compressed air cylinders in this lifeboat required the removal of the center divider and seats.
An inspection of the intact cylinder and the ruptured cylinder fragment showed significant corrosion. While the exact cause of the corrosion is unknown, it is suspected that the cylinders were partially submerged in water and subjected to accelerated corrosion due to the presence of dissimilar metals. Although stray electrical currents were considered as a potential cause, they were deemed unlikely given the lifeboat’s electrical configuration and the OCS unit’s secured power.
Recommendations
The Coast Guard recommends that owners, manufacturers, operators, and service providers:
- Verify the physical condition of the entire cylinders during annual lifeboat inspections.
- Ensure air cylinder stowage compartments are maintained in a dry condition
- Ensure that the air cylinders are inspected and maintained in accordance with 46 CFR 147.60, applicable to USCG approved lifeboats through 46 CFR 160.135-7(b)(25). These cites invoke 49 CFR 180 that addresses corrosion and abraded areas, among other signs of defect or damage.
- Implement training for all personnel responsible for lifeboat maintenance or operation to provide awareness of the necessity for proper maintenance and inspection of lifeboat compressed air cylinders for all types of cylinder construction.
- Consider approved design changes that provide for routine access to all portions of the cylinders for proper inspection and maintenance.
The Coast Guard also recommends that appropriate safety measures are implemented for any lifeboats that are not in active service (e.g. spare boats or boats removed from service for maintenance) or are part of an inspected vessel or unit that is no longer in active service. Safety measures could include, but are not limited to, bleeding pressure from the cylinders, removal of the cylinders from the lifeboat, or continuing regular inspection of the cylinders.
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Source: USCG
