Introduction

Marine pollution is one of the most serious concerns in the shipping industry, and oily water discharges from machinery spaces are a primary source of deficiencies. The Oily Water Separator (OWS), together with its associated 15 PPM bilge alarm, is the frontline safeguard against such discharges.

For Port State Control (PSC) officers, OWS inspections are a standard yet highly sensitive part of shipboard safety and environmental compliance checks. Failures in this system often lead to deficiencies, detentions, and even prosecution. This blog explores the regulatory framework, common deficiencies, and a real case study from an onboard PSC inspection.


Regulatory Requirements

Under MARPOL Annex I – 𝗥𝗲𝗴𝘂𝗹𝗮𝘁𝗶𝗼𝗻𝟭𝟰.𝟳:

  1. Ships of 400 GT and above must be fitted with an oily water separating system
  2. The system must include:
  3. A 15 PPM bilge alarm
  4. An automatic stopping device to prevent discharge above the limit
  5. According to MEPC.107(49), equipment must be type-approved and regularly maintained to ensure accuracy and reliability.

Certain exemptions may apply to ships above 400 GT but under 500 GT.

Failure to comply with these requirements not only risks pollution but also exposes the vessel and its crew to serious enforcement actions.


Common Deficiencies Detected During PSC Inspections

PSC officers frequently detect issues with OWS systems, including:

  1. Non-Operational 15 PPM alarms
  2. bypassed systems
  3. Faulty automatic stopping devices
  4. Tampered OCM units (e.g., deliberate bypasses or “magic pipes”)
  5. Inaccurate Oil Record Book (ORB) entries
  6. Improper crew training on OWS operation
  7. Poor maintenance and calibration of the system (Calibration certificate NOT ON BOARD)

Such findings often result in ship detention and endanger the ship’s commercial operations.


Special Considerations in the Persian Gulf

The Persian Gulf is designated as a Special Area under MARPOL Annex I (adopted in November 1973), meaning stricter controls apply to the discharge of oily mixtures. In this region, even minimal violations can result in significant consequences for both the vessel and its operator.

Key aspects to consider:

  1. Discharge Restrictions: Oily water discharge is only permitted when processed through an OWS and proven to be below 15 ppm, with the system automatically stopping any excess.
  2. Environmental Sensitivity: The semi-enclosed nature of the Gulf makes it highly vulnerable to pollution. Even minor discharges can have a major ecological impact.
  3. PSC Enforcement: Port State Control authorities in the region are particularly strict on OWS compliance. Deficiencies or evidence of bypass arrangements often lead to immediate detention.

For ship operators, this underscores the importance of ensuring that oily water separators and bilge alarm systems are fully operational, records are accurate, and the crew is trained to manage bilge water in compliance with MARPOL requirements.


Case Study: Testing the 15 PPM Bilge Alarm During a PSC Inspection

During a recent onboard PSC inspection, the 15 PPM bilge alarm was tested to verify proper operation of the OWS. This device ensures that no discharge exceeding the allowable limit is released overboard


Observations

  1. The alarm was confirmed to activate correctly.
  2. The system was capable of automatically stopping discharge once the 15 PPM limit was reached.

Lessons from Industry Experience

Despite this case being compliant, common issues include:

  1. Alarm bypassing
  2. Automatic stopping device not functioning
  3. OCM calibration errors
  4. ORB entries not matching actual operations
  5. Crew unaware of proper OWS procedures

This highlights the importance of routine checks and crew awareness training to ensure both compliance and environmental protection.


Conclusion

The Oily Water Separator and its associated monitoring devices are among the most critical pieces of environmental protection equipment onboard. For PSC inspections, OWS performance is a key compliance indicator.

By maintaining functionality, keeping transparent records, and ensuring crew competence, ship operators not only protect the marine environment but also safeguard their vessels from costly detentions and legal repercussions.


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This video highlights the testing of oily water separator system.