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MEO CLASS 1 · ORAL QUESTION 32

Briefly explain NOx code, what are NOx technical file contents?

Answer

The NOx​ Technical Code (mandatory under MARPOL Annex VI, Regulation 13) provides the statutory requirements for the testing, survey, and certification of marine diesel engines (>130 kW) to ensure compliance with global NOx​ emission limits.

It outlines the testing procedures on the manufacturer's test bed, defines the Engine Family / Engine Group concept, and details the procedures for initial and periodic onboard verification.

Key Contents of the NOx​ Technical File

Every certified engine on board must be accompanied by an approved, ship-and-engine-specific NOx​ Technical File. This file forms the basis for Class and Port State Control (PSC) surveys. Its mandatory contents include:

  1. Engine Identification & Specifications:

    • Serial number, engine model, rated power (kW), rated speed (rpm), and intended application/test cycle (e.g., E2/E3 for main propulsion, D2 for generator sets).

    • EIAPP Certificate reference details.

  2. List of NOx​-Critical Components & IMO Markings:

    • A complete list of all components influencing NOx​ formation, along with their unique IMO identification markings (which must match the physical stamps on installed parts):

      • Fuel injectors / nozzles

      • Fuel injection pumps and cams

      • Cylinder head, piston crown, and cylinder liner

      • Turbocharger specification (diffuser, nozzle ring, rotor)

      • Charge air cooler model/specification

      • Exhaust gas recirculation (EGR) or Selective Catalytic Reduction (SCR) components (if fitted).

  3. Engine Settings & Operating Parameters:

    • Allowable ranges for adjustable settings affecting emissions:

      • Fuel injection timing / VIT (Variable Injection Timing) settings.

      • Maximum cylinder pressures (Pmax​) and scavenge air temperature/pressure limits.

  4. Designated Onboard Verification Method:

    • Clear instructions for the method used to verify engine compliance during periodic surveys (usually the Engine Parameter Check Method).

  5. Record Book of Engine Parameters:

    • A log (or reference to a dedicated logbook) maintained by the ship's crew to record any changes, adjustments, or component replacements involving NOx​-critical parts during maintenance.

  6. Parent Engine Test Data:

    • Summary of the test-bed emission data obtained from the Parent Engine representing the engine family.