Overview
ISO 21963:2020 - Ships and marine technology - Marine environment protection - Tanks and piping systems for facilitating 5 ppm oil-water separation - defines requirements and test methods for tanks, piping and oil-water separation systems (OWSE) used on fixed offshore marine structures and ships operating in designated sea areas. The standard supports environmental compliance by specifying equipment and installation criteria for treatment systems that reduce oil-in-water concentrations to equal to or less than 5 ppm.
Key Topics and Technical Requirements
- Scope & applicability
- Applies to fixed offshore marine structures and ships in designated sea areas where optimized treatment to ≤5 ppm is required.
- Oil-water separation equipment (OWSE)
- OWSE must be suitable for offshore use, corrosion-resistant and type-approved as required by Administrations.
- Functional OWSE components: 5 ppm oil-water separator (OWS), 5 ppm oil content meter (OCM), and automatic discharge stopping device (ADSD).
- 5 ppm OWS
- Designed for automatic, continuous operation (minimum 24 h duty), with fail‑safe arrangements to prevent overboard discharge on malfunction.
- May use gravity separation, filtration, coalescence or combinations to achieve ≤5 ppm.
- Wear parts must be accessible for maintenance; nameplate with operational limits is required.
- Oil content meter (OCM)
- Resolution of 1 ppm with a ppm display; unaffected by emulsions or oil type.
- Response time ≤ 5 s; alarm if oil >5 ppm or if flushed for >5 s.
- Accuracy checks at least every 5 years (manufacturer or authorized entity); type approval required.
- Bilge alarm data retention for at least 18 months; anti-tamper seals required.
- Automatic discharge stopping device (ADSD)
- Automatically prevents discharge overboard when effluent >5 ppm or on OCM failure by diverting flow back to source or holding tank.
- Overall response time (OCM + ADSD) shall be as short as possible and not exceed 20 s.
- Installation & testing
- Sampling point close to OWS outlet; recirculation facilities for testing; supply pump capacity limit (≤90% of OWS rated).
- Type-approval of switchboard per Annex C; testing of systems per Annex B.
Practical Applications & Who Uses It
- Marine and offshore operators seeking regulatory compliance with strict oil discharge limits.
- Shipbuilders, offshore platform designers, and piping/tank system engineers specifying OWSE installations.
- Manufacturers of oil-water separators, oil content meters (OCM) and automatic discharge stopping devices.
- Classification societies, flag Administrations, and surveyors performing type-approval, inspection and certification.
- Environmental managers and compliance officers implementing MARPOL‑aligned controls in sensitive sea areas.
Related Standards (normative references)
- ISO 8217 - Petroleum products - Specifications of marine fuels
- ISO 9377-2 - Water quality - Determination of hydrocarbon oil index (solvent extraction and GC)
Keywords: ISO 21963:2020, 5 ppm oil-water separation, oil content meter, OCM, ADSD, OWSE, marine environment protection, fixed offshore marine structures, shipboard bilge treatment.