Technical Circular No: 024/2025
1. U.S. Coast Guard (USCG) has issued Marine Safety Alert 16-25, addressing potential failures in high-pressure water mist nozzles due to corrosion (green patina build-up), and to advise operators to ensure proper inspection and maintenance prior to Port State Control (PSC) inspections in U.S. ports.
2. The safety alert was issued after multiple “HI-FOG” system high-pressure water mist nozzles (Marioff “a2000” series) failed to discharge water during a routine inspection of a fixed firefighting system aboard a foreign passenger vessel by USCG Port State Control Officers.
3. The investigation of above incident revealed that corrosion by green patina build-up had rendered the nozzles inoperable, even after the glass bulb actuator had broken as intended. The nozzle design relies on holding a standing pressure of 25 bar (363 PSI) and activating further to 140 bar (2,031 PSI) for full mist discharge. However, even after manually increasing the system pressure, as per manufacturer guidelines, the affected nozzles failed to release water.
4. In view of the above, the USCG has provided following guidelines to the owners, operators, technical managers and crew of the vessel:
a. Inspect all high-pressure water mist nozzles on board for corrosion or green patina particularly those over 10 years old or located in high-moisture environments (e.g., outer decks, galleys, spas, pool areas, and near exterior doors).
b. Review crew training procedures to ensure personnel responsible for firefighting equipment are able to identify signs of nozzle corrosion during routine maintenance or walk-throughs.
c. Conduct additional inspections, if necessary, beyond scheduled maintenance intervals particularly in high-risk areas.
d. Consult the manufacturer (Marioff) for guidance if corrosion or malfunction is found. Replace nozzles as needed.
e. Be aware that increasing system pressure to 140 bars may not always restore nozzle functionality, even when recommended by the manufacturer.
f. This Safety Alert is intended for awareness and does not supersede any statutory or regulatory requirements
5. Above is for information and compliance.
Enclosure:
This Technical Circular and the material contained in it is provided only for the purpose of supplying current information to the reader and not as an advice to be relied upon by any person. While we have taken utmost care to be as factual as possible, readers/ users are advised to verify the exact text and content of the Regulation from the original source/ issuing Authority.