USCG safety alert: Corrosion risks in lifeboat air cylinders

The United States Coast Guard issued safety alert 08-24 to raise awareness about the potential dangers posed by insufficiently inspected compressed air cylinders in lifeboat self-contained air support systems. The alert was triggered by an incident that occurred during a routine inspection of a lifeboat on an unmanned offshore platform awaiting decommissioning. The incident involved a ruptured compressed air cylinder, which caused significant damage and raised concerns about the condition of other similar cylinders.

Incident Description:

Discovery of Damage: During the inspection of a lifeboat, a large hole was found in the structure. Upon further investigation, it was determined that a cylinder from the lifeboat's air support system had ruptured, sending fragments into the flotation chamber. One of the three cylinders was lost at sea, and its condition remains unknown, while the third cylinder remained in its storage location but showed severe corrosion.
Cylinder Storage Issues: The cylinders were stored horizontally in or just above the bilge area beneath the centerline seats. While lifeboat canopies are required to be watertight, water ingress is common in the bilge and cylinder storage compartments. In this case, although the compartment was designed to isolate the cylinders from the bilge, it was not fully watertight and had accumulated several inches of water. This water exposure likely contributed to accelerated corrosion of the cylinders.
Inspection Findings: The remaining cylinder, which had not ruptured, showed deep pitting and significant corrosion. Although the cylinders were inspected annually and within their hydrostatic testing period, the corrosion went undetected. The damage was especially concerning because the cylinders were relatively new (just five years old), yet the corrosion indicated serious deterioration.

Corrosion Cause:

The exact cause of the corrosion is not fully known, but several factors likely contributed:

Water Submersion: The cylinders may have been partially submerged in water, leading to accelerated corrosion, especially when exposed to dissimilar metals.
Environmental Factors: The corrosion was likely exacerbated by the lifeboat being in an unmanned state for an extended period, without the routine inspections and maintenance typically applied to active lifeboats.

Risk Assessment:

The incident could have resulted in fatal or severe injuries if personnel had been nearby during the rupture. The corrosion and subsequent rupture of the cylinder highlight the importance of maintaining lifeboats and their associated systems, particularly in environments prone to water exposure.

Coast Guard Recommendations:

To mitigate the risks associated with corroded lifeboat cylinders, the Coast Guard recommends the following:

Thorough Inspections: During annual lifeboat inspections, ensure that the entire air cylinder is visually inspected. Consider methods that allow full access to the cylinders, such as using cameras or removing parts to view all surfaces. The inspection should also cover any compartments where the cylinders are stored, to ensure they are dry and free from water ingress.
Proper Storage Conditions: Ensure that air cylinder storage compartments are maintained in a dry condition. Water accumulation can accelerate corrosion, so maintaining a watertight environment is critical to preventing damage to the cylinders.
Compliance with Standards: Adhere to the maintenance and inspection standards outlined in 46 CFR 147.60 for USCG-approved lifeboats, along with relevant parts of 46 CFR 160.135-7(b)(25). These regulations align with the 49 CFR 180, which addresses corrosion, abrasion, and other forms of damage to the cylinders.
Personnel Training: Ensure that all personnel responsible for lifeboat maintenance and operations are trained to understand the importance of proper inspection and maintenance procedures for compressed air cylinders. This training should cover all types of cylinder construction and maintenance techniques.
Design Modifications: Consider approved design changes that would allow easier access to all parts of the air cylinders for more effective inspection and maintenance. This could involve redesigning the compartment to make it more accessible or ensuring that cylinders are stored in locations that are easier to inspect.
Safety Measures for Inactive Lifeboats: For lifeboats that are not in active service (such as spare lifeboats or boats removed for maintenance), the Coast Guard recommends implementing safety measures like:

Bleeding pressure from the cylinders to prevent buildup.
Removing cylinders from lifeboats entirely for storage and inspection.
Continuing to perform regular inspections, even for lifeboats that are temporarily out of service, to ensure their readiness.