The Norwegian Maritime Authority (NMA) has issued a significant safety warning regarding a critical flaw found in the design of emergency stop (E-stop) devices on some vessels. Specifically, the NMA is concerned about systems that utilize “open circuits.”
The Danger of Open Circuit Emergency Stops
The core problem with an open circuit emergency stop is its inherent vulnerability:
- Failure Mode: If a cable breaks or another fault occurs within the emergency stop circuit, the emergency stop function itself becomes inoperable.
- Continued Operation: Crucially, this failure does not prevent the machinery or equipment from being started and operated. This creates a false sense of security, as personnel might assume the safety function is active when it is not.
- Severe Consequences: The inability to activate an emergency stop when needed can lead to uncontrolled machinery, severe personal injury, fatalities, environmental pollution, or significant damage to the vessel or cargo.
Corrective Measures Mandated by NMA
To mitigate these risks, the NMA mandates that all vessels implement stringent operational and maintenance procedures to ensure the correct and reliable functioning of all safety-critical equipment, including emergency stop devices. The following specific measures are to be implemented or already in place:
- Function Testing: Vessels must establish procedures for regular testing of all emergency stops. This is especially vital for systems based on open circuits, where hidden faults are a significant concern. Regular testing can identify these failures before an emergency arises.
- Error Protection: For emergency stops connected in open circuits, a thorough assessment must be conducted to determine if technical improvements are necessary. The NMA suggests implementing more robust solutions such as closed circuits (where a break in the circuit triggers the stop, inherently safer) or redundant solutions (where multiple systems are in place to ensure the function even if one fails).
- Maintenance and Control: The functionality of emergency stops must be explicitly incorporated into the vessel’s comprehensive maintenance and inspection program. Any faults identified during these checks must be rectified immediately to restore full functionality.
Relevant Legislation Reinforcing Safety
The NMA’s directives are firmly rooted in existing Norwegian maritime legislation, emphasizing the company’s responsibility for safety management and equipment reliability:
- Regulations on safety management for small cargo ships, passenger ships and fishing vessels, etc. – Section 9 (Maintenance and vital equipment): This regulation mandates that companies develop, follow, and document a maintenance system to ensure vessels and equipment comply with requirements. Crucially, it requires identifying equipment and technical systems where sudden operational failure could lead to dangerous situations and implementing measures to improve their reliability, including regular testing of backup or non-continuously operating systems.
- Regulations on a safety management system for Norwegian ships and mobile offshore units – Annex to the Regulations (ISM) 10.3: This section of the ISM Code (International Safety Management Code) specifically requires companies to identify equipment and technical systems whose sudden failure could create hazardous situations. It mandates that the Safety Management System (SMS) include specific measures to promote the reliability of such equipment or systems, including regular testing of stand-by arrangements and systems not in continuous use.
- Regulations on the working environment, health and safety of persons working on board ship – Chapters 2 and 4:
- Section 2-2 Risk assessment: This section requires the regular identification and assessment of hazards on board, with written documentation of the results. If a risk to health and safety is identified, necessary measures must be taken to eliminate or reduce it.
- Chapter 4, Section 4-4 (Inspection and maintenance of work equipment): This provision dictates that work equipment exposed to deterioration likely to cause hazardous situations must undergo adequate inspection to identify and counteract such hazards, with all inspections being documented.
By issuing this circular, the Norwegian Maritime Authority underscores the critical importance of robust safety systems and proactive maintenance, particularly for emergency functions, to prevent accidents and ensure the well-being of seafarers and environmental protection.
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Source: Norwegian Maritime Authority
