Changes to sulphur verification procedures under MARPOL Annex VI

The 74th session of the IMO’s Marine Environment Protection Committee (MEPC 74) approved amendments MARPOL Annex VI related to verification procedures to determine whether the fuel oil delivered to, in-use or carried for use on board a ship is in accordance with the applicable sulphur limit of regulation 14 of MARPOL Annex VI.

The amendments are a result of work undertaken at the IMO to ensure consistent implementation of the 0.50% sulphur limit taking effect from 1 January 2020, however, assuming the amendments are formally adopted at MEPC 75 in early April next year, they would only enter into force in the second half of 2021.

The IMO has therefore issued a circular, MEPC.1/Circ.882, inviting Member Governments to apply the approved amendments to MARPOL Annex VI related to the verification procedure for a MARPOL Annex VI fuel oil sample in advance of their entry into force in order to “ensure a consistent approach to verifying the sulphur limit of the fuel oil delivered to, in-use or carried for use on board a ship until the entry into force of the approved amendments.”

Apart from amendments to the sulphur verification procedure described in appendix VI, the circular also draws attention to other relevant amendments, including new definitions added to Regulation 2 of MARPOL Annex VI.

One of these definitions is for “Sulphur content of fuel oil”, linking it to the ISO 8754: 2003 test method. This was originally proposed to the IMO by IBIA to ensure consistency in the testing and reporting protocol for sulphur across all jurisdictions. The test method is also referenced in the “2019 Guidelines on consistent implementation of 0.50% sulphur limit under MARPOL Annex VI” following a proposal co-sponsored by IBIA and member states.

New definitions under regulation 2 also include explanations of the difference between a MARPOL delivered sample, in-use sample and on board sample, all of which can be used by relevant authorities to test for compliance with sulphur limits. Regulation 14 has also been amended with additional paragraphs about obtaining in-use and on board fuel oil samples for sulphur verification by the competent authorities.

In this context, MEPC 74 also approved revisions to guidelines for obtaining representative in-use samples for sulphur verification. Guidelines for taking on board samples of fuel oil intended for use by the ship (e.g. from bunker tanks) have yet to be developed but could be developed and approved during 2020.

These three types of samples are not treated the same when it comes to the amended procedures in appendix VI to MARPOL Annex VI for sulphur verification. Prior to the recently approved amendments, appendix VI referred only to the representative fuel oil sample (the “MARPOL sample”) to verify the sulphur content of the fuel oil supplied to a ship. This is now defined as the MARPOL delivered sample.

The current procedure under appendix VI for verification of the MARPOL sample requires the average of two test results from a single laboratory to test at or below the applicable sulphur limit to be deemed compliant. If it exceeds the limit + 0.59R (the 95% confidence limit for precision of the test method) it will be deemed non-compliant, but if it is between the limit and the limit +0.59R the sample should be sent for analysis at a second laboratory for a further two test results. The average of all four test results must meet the limit.

The amended appendix VI relies on the average of two tests at a single laboratory, and has two different procedures. The procedures are very detailed but in summary, the key points are as follows:

Sulphur verification procedure for MARPOL delivered sample:
The average test result from one laboratory must be at or below the applicable limit, e.g.0.10% or 0.50% sulphur, to be considered to have met the requirement of the regulation. This means that 95% confidence, or 0.59R (where R is the reproducibility of the test method) does not apply to MARPOL delivered samples.

Sulphur verification procedure for in-use and onboard samples:
The 95% confidence principle will apply, meaning an average test result up to the limit +0.59R will be considered to have met the regulatory requirement. This means a test value of up to 0.11% against the 0.10% sulphur limit and up to 0.53% against the 0.50% sulphur limit will be considered to have met the requirement.

IBIA is happy to see that test precision, or 95% confidence, has been taken into account for in-use and on board samples from ships. IBIA has been campaigning for years to ensure these principles are recognised so as not to risk penalising ships for exceeding sulphur limits based on test results that are marginally above the limit, but within the Reproducibility (0.59R) of the test method.

Along with IPIECA, IBIA had asked for MEPC 74 to apply the same principle to the MARPOL delivered sample. If that could not be agreed, we proposed to at least retain the use of a second laboratory if the result from the first laboratory was above the limit but within 95% confidence to safeguard against an unfairly biased outcome. This is what 0.59R recognises; that two laboratories testing the same sample may have slightly different results. Our reasons were outlined in MEPC 74/10/11 and while the proposal was extensively discussed and gained significant support at MEPC 74, a small majority was firmly opposed to it.

IPIECA’s Eddy Van Bouwel and IBIA’s Unni Einemo at MEPC 74

We did, however, manage to get a change to the language regarding the outcome of the testing done in the laboratory. In the draft amendments, it said: “The results obtained from this verification procedure are final.” After long discussions at the working group that was tasked with finalising the amendments to MARPOL Annex VI, this was adjusted to “The final results obtained from this verification procedure shall be evaluated by the competent authority.” This slight adjustment to the text allows for the authority to evaluate if the test result should be taken at face value as a pass/fail. If there is doubt, the authority could decide to send the sample to a second laboratory for further verification. There is a potential need for developing additional guidance on how to conduct this evaluation in a uniform and consistent way. IBIA will likely continue to cooperate with IPIECA and other interested parties on formulating such guidance.

The key message for the bunker supply industry is that, in order to be 95% certain that the product will not test above the actual limit, the blend target must be the limit minus 0.59R, meaning 0.47% when producing fuels to meet the 0.50% sulphur limit and 0.09% when producing fuels to meet the 0.10% sulphur limit. This principle applies to all specified limits and is covered in paragraph 4.7 “Testing and interpretation of test results” on page 11 of IBIA’s “Best practice guidance for suppliers for assuring the quality of bunkers delivered to ships”.

Share this: