202418 : Caution call for condensate in air lines

28 Feb 2024 MARS

As edited from USCG Safety Alert 08-23 http://tinyurl.com/MARS202418

A recent investigation of a fire and subsequent loss of propulsion on a vessel caused by condensate forming in air lines is a cautionary tale. In this case, condensate formed in air lines that supplied compressed air to the vessel’s air-operated engine throttle and clutch control systems. There are many systems vital to vessel and personnel safety which depend upon the reliable, uninterrupted flow of contaminant-free compressed air. Propulsion control equipment (pneumatic engine starters, throttle controls, governors, air-operated clutch systems, etc.) and pneumatically operated air-blowers used in gas-freeing operations are just a few examples of such equipment.

Condensate forming within the air lines of a compressed air system indicates that the compressed air has not been adequately dried for the ambient operating temperature to which the air lines are exposed. When this happens, the temperature of the compressed air can drop below its pressure dew point and water vapour in the air may condense. This contaminates the air lines with moisture, which can cause an unexpected failure of air-operated equipment due to the restriction or blockage in the flow of compressed air, excessive corrosion, and failure of internal components. In cold weather, the condensate can freeze, potentially blocking the flow of compressed air or cause the pneumatic engine throttle and clutch controls to stick or freeze.

Additionally, this condition may create other environmental hazards such as increased generation of static electricity when used with pneumatic blowers/tools. To ensure the safe and reliable operation of air-operated equipment, it is critical that the supplied compressed air is free of moisture and other contaminants.

Lessons learned

  • Identify compressed air systems vital to the safety of the vessel and/or personnel and ensure their arrangements are properly designed and installed for the ambient operating temperature and have adequate air-drying processes.