The NOx Technical Code is the IMO's regulations for how NOx emissions from ship engines should be measured, documented, and certified. Ecoxy performs accredited measurements according to the code – onboard, at the dock, or during sailing – and delivers the documentation required by the flag state, classification society, and NOx fund.
The NOx Technical Code 2008 (NTC 2008) is the technical code under MARPOL Annex VI regulation 13. It describes how a marine diesel engine should be tested, inspected, and certified so that the emission of nitrogen oxides (NOx) can be documented against the limits in Tier I, II, and III.
The code applies to all marine diesel engines with a power output of over 130 kW that are installed on ships built on or after January 1, 2000, and engines that have undergone a 'major overhaul' after the same date. This includes both main engines and auxiliary engines.
The goal is that the NOx emissions from an engine can be documented in the same way regardless of where the ship is built, who owns it, and what flag it flies.
In summary: The engine is pre-certified on a test bench, receives an EIAPP certificate and a Technical File, and must then be able to demonstrate during inspections onboard that it is still within the limit. Ecoxy provides the measurements required at all these stages.
The limit value depends on the engine's nominal speed (n, rpm) and when the ship was built. The values are in g/kWh, weighted over the test cycle.
Tier III applies only when the ship operates in a NOx emission control area (NECA): North America and the U.S. Caribbean for ships built from 2016, the North Sea and the Baltic Sea for ships built from January 1, 2021. Outside these areas, Tier II applies.
For a typical medium-speed engine at 1,000 rpm, the formula gives approximately 11.3 g/kWh in Tier I, 9.0 g/kWh in Tier II, and 2.3 g/kWh in Tier III.
The code describes three steps: pre-certification, documentation, and onboard verification
The engine, or a representative 'parent engine' for an engine family, is tested over a defined cycle: E2 for constant speed (diesel-electric, CPP), E3 for propeller curve, D2 for auxiliary engines, and C1 for variable load. The result is the weighted NOx value compared to the Tier limit, and the basis for the EIAPP certificate.
Each engine shall have a Technical File describing NOx-critical components, settings, and operating values, and a Record Book of Engine Parameters where changes are recorded. Together with the EIAPP certificate, this is the documentation inspectors request during inspection.
At the first inspection, annual and periodic inspections, and after major modifications, it must be shown that the engine is still within the limit. The code allows three methods: parameter control against the Technical File, simplified measurement onboard, and direct measurement and monitoring. Ecoxy performs the latter two.
Accredited measurement according to the NOx Technical Code and ISO 8178 since 2008
Simplified measurement and direct measurement according to the code's chapter 6, at four load points for main engines and at 50% for auxiliary engines. Performed at the dock or underway, adapted to the ship's sailing schedule.
Ecoxy is accredited by Norwegian Accreditation (NA TEST 225) and approved by the Maritime Directorate as a competent operator. The report is accepted by the flag state, classification society, and the NOx fund.
New engine, SCR system, or changes to NOx-critical components trigger new documentation. We measure, update the basis for the Technical File, and provide the engine with the numbers it needs for renewed certification.
NOx measurement according to the code is often combined with measurement for the NOx fund, documentation of emission factors for the EU ETS report, and measurements of CO₂, SO₂, and particles – in one trip on board.
The requirements apply to engines installed on ships built from January 1, 2000. Older engines are covered if they undergo a major conversion – for example, switching to an engine of a different type or a change that increases NOx emissions by more than 10%.
ISO 8178 is the general standard for measuring exhaust emissions from combustion engines, with test cycles E2, E3, D2, and C1. The NOx Technical Code is based on ISO 8178 but provides the specific rules for certifying marine engines under MARPOL. Ecoxy measures according to both.
Yes. Direct measurement on board is one of the methods the code allows, and for many shipping companies, measurement during sailing is the least costly solution because the ship does not require extra lay time.
Ships with SCR systems or EGR that are to meet Tier III must document the emissions both with and without the treatment system in operation, in accordance with the code's provisions for such systems. We measure both conditions in the same assignment.
Specify vessel, engines, and desired timeframe, and we will get back to you with a proposal for implementation within 24 hours on weekdays.
Accreditations and certifications
NA TEST 225
NA VV-003
Kiwa Certified
Kiwa ISO 14001
Achilles
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