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By Olav Tveit, DNV Petroleum Services

With the entry into force of the North Sea SECA there will be increased pressure on charterers and operators to provide ships with low sulphur fuel oil.

MARPOL Annex VI, Regulations for the Prevention of Air Pollution from Ships, entered into force on 19th May 2005. MARPOL Annex VI Regulation 14 restricts SOx emissions from ships by introducing a maximum sulphur content in marine fuels of 4.5 per cent. In addition, MARPOL Annex VI identifies SOx emission control areas (SECAs). In these areas the maximum sulphur content of marine fuels used is 1.5 per cent. The Annex also set forth requirements for documentation and representative sampling of fuel oil.

EU Directive 2005/33/EC deals with issues similar to those in MARPOL Annex VI, although its dates for implementation do not coincide with those of Annex VI. It also provides for a maximum sulphur content in marine gas oils of 0.2 per cent from 11th August 2006. Further, there will be a reduction of sulphur content of marine fuels for vessels at berth in EU ports, the entry into force date being 2010, with the maximum sulphur content from that date being 0.1 per cent. Other implementation dates are as follows:

On 19th May 2006 the Baltic Sea SECA under IMO came into force. On 11th August 2006 the Baltic Sea SECA became enforceable by EU member states. On 11th August 2007 the North Sea SECA will become enforceable by EU member states. On 21st November 2007 the North Sea SECA enters into force under IMO.

Bunker management
There is uncertainty as to whether suppliers will be able to meet the demand for low sulphur fuel oil (LSFO) in main bunker ports world-wide. What is clear today is that operators with a contract for LSFO in general have their demands covered by the majors/larger independents at main bunker ports at a premium of USD 30-50/MT. Fortunately, it appears so far that the demand has been met with respect to the Baltic Sea SECA. There is, however, uncertainty as to whether world-wide supply will be sufficient when the North Sea SECA enters into force next year.

Needless to say, the pressure on charterers and operators to provide ships with LSFO will increase. As a result, bunker management will be more complex. It is also vital that owners/charterers and bunker purchasers ensure that MARPOL Annex VI clauses (Regulations 14 and18) are included in their charterparties and bunker purchase confirmations. INTERTANKO has developed contract clauses that may be suitable in this respect.1

Bunker quality
In order to produce LSFO refineries have the following options:

– Use inherently low sulphur crude stocks.
– Invest in de-sulphurisation units.
– Blend to LSFO specification, using a variety of cutter stocks, inland quality LSFO or purchased inherently LSFO.

The blending option seems to be the preferred future method. Regrettably, it appears that this option is also the one which could impact the bunker quality in a negative way as explained below.

Increased stability and compatibility problems
The more you blend, the greater the risk of making products unstable. This should be detected through fuel quality testing (total sediment potential). However, if products are blended on the stability limit, subsequent mixing on board with an existing fuel with different properties (e.g., viscosity, density) or gas oil/diesel oil could lead to unstable fuels and subsequent sludging. The risk increases during LSFO change-over, depending on system configuration.

Sulphur content deviations
In some cases certain ports blend to the sulphur limit of just below 4.5 per cent. From time to time, the 4.5 per cent limit may be exceeded, although marginally.

Some samples tested also exceed the 1.5 per cent limit, although in most cases only marginally. The IMO has not yet provided guidance as to whether an allowance can be made, like for instance whether 1.54 per cent can be acceptable as 1.5 per cent. Currently this is left to the discretion of the individual port and flag states.

Some suppliers and certain testing companies introduce a default standard margin of error (reproducibility). It is argued that deviations above 4.5 per cent or 1.5 per cent would be caused by a default margin of error during testing. The problem is that the concept of margins of error has not been discussed at IMO so one can not say whether authorities will accept any result above 1.5 per cent in a subsequent flag or port state control. Hence, until further notice it is recommended that any indication of sulphur levels above 4.5 per cent or 1.5 per cent respectively should be accompanied by a notification to the flag administration, bunker port administration and supplier according to the requirements of the IMO Port State Control Guidelines for MARPOL Annex VI.2

Following the ISO 4259 standard, for a supplier to be 95 per cent confident that the fuel delivered will have a sulphur level of 1.50 per cent, the suppliers’ target should not be higher than 1.42 per cent.

Considering the possible margin of error, as well as the aspect of fuel oil change-over, owners should consider whether a limit of 1.5 per cent in orders is sufficient or whether they should specify a lower sulphur limit.

Increased levels of catfines (Al/Si)
With decreasing sulphur content there may be an increasing level of catfines. This may be due to an increased use of cycle oils as cutter stock in the fuel blend (cycle oils are a low sulphur, highly viscous refinery product which tends to contain an elevated amount of catfines).

Increased ignition and combustion problems
Increasing ignition and combustion problems may also occur when using LSFO. This could be related to an increased use of high density and high aromatic cycle oils as cutter stock during blending.

Bunker deliveries
MARPOL Annex VI has not yet been subject to significant enforcement and as such the stringency applied is uncertain. It is recommended that ships adhere to the MARPOL Annex VI sampling procedures and documentation requirements as laid down in IMO Resolution MEPC 96(47).3 At the recent IMO MEPC 54 meeting a circular was adopted urging IMO member states to ensure that bunker suppliers within their jurisdiction apply this resolution.

As a minimum, the crew must verify the sulphur content in the bunker delivery notes and that the official MARPOL sample is representative of the bunker supplied. In accordance with the IMO Port State Control Guidelines for MARPOL Annex VI, any non-compliance must be reported through a notification to the flag state and the bunker port authorities.


For details go to www.intertanko.com.

2 www.imo.org/includes/blastDataOnly.asp/data_id%3D12749/472.pdf.
3  A copy can be found at www.intertanko.com/pdf/weeklynews/MEPC%2096-47%20Resolution%20-%20Bunker%20sampling.pdf#search=%22IMO% 20Resolution%20MEPC%2096(47)%22.

High sulphur fuels
It is of vital importance that operators specify and crew verify that the sulphur level in the bunker delivery note is below the respective MARPOL limits.

In the event a fuel testing company detects a sulphur level which exceeds the MARPOL limits and is above that specified in the bunker delivery note, the following course of action should be taken:

– A notification should be sent to the flag state and the bunker port authorities, highlighting the indicated sulphur level deviating from the bunker delivery note level.
– It would be unreasonable for the administration to require the ship to deviate due to a possible non-compliance for which a supplier is responsible. The operator should therefore request that the ship be permitted to proceed to the next port of call.
– The operator should agree with the flag state administration regarding verification testing of the on board MARPOL sample (the on board MARPOL sample is the official sample which is legally binding). If the supplier’s MARPOL sample has not been taken in accordance with the IMO sampling guidelines, then the operator should propose to test the ship’s MARPOL sample (if taken) as well. It is the prerogative of the administration to select an appropriate laboratory for the purpose of verification testing. However, the administration should be encouraged to select a laboratory which is accredited with respect to the ISO sulphur test method and has documented experience with fuel testing. The laboratory should, in addition to sulphur, also test for fingerprint parameters such as density, viscosity, nickel and vanadium. The MARPOL sample should be forwarded to the laboratory in question. The result is to be communicated to the administration, which is subsequently obliged to inform the bunker port state administration.
– In case non-compliant fuel is detected, de-bunkering is not the only option available. As an emergency measure, provided existing fuel is on board and it is verified compatible with the new fuel, the owner may request acceptance for on board blending (depending on sulphur differences, the blending ratio could be very low). This procedure has been successfully adopted and accepted by at least two administrations.

Fuel change-over
Fuel change-over contains both commercial and statutory compliance elements. On the commercial side, with a premium of up to USD 30-70/MT, the change-over from normal to LSFO and vice-versa should be as fast as possible. On the statutory compliance side, owners need to be confident that the crew has managed to change over from normal to LSFO before crossing the SECA boundary.

With a high sulphur limit of 4 per cent and a LSFO level of 1.49 per cent, reaching the required 1.5 per cent limit will take time, if it can be done at all.

Although not yet specifically required, realistic and proven change-over procedures should be developed for each ship or group of ships with similar fuel tank configuration and system set-up.

The pre-requisite for change-over is the exact sulphur level of existing fuel and LSFO, i.e., a bunker delivery note sulphur level set as “less than 4.5 per cent” and “less than 1.5 per cent” should not be accepted as it creates uncertainty regarding change-over time (in addition to uncertainty regarding the selected base number (TBN) of the cylinder lube oil used on board).

Some owners have converted their ships by dedicating a bunker tank to LSFO with separate bunker line, as well as introducing separate LSFO service and settling tank with piping ensuring split separator operation. This option means that the change-over can be carried out quickly.

However, the majority of ships have conventional fuel oil systems with a limited number of bunker tanks and only one service and settling tank. For these ships the main contributors to change-over time are the following:

– Total consumption (main engine + auxiliary engines + boilers).
– Total volume of high sulphur fuel oil remaining in piping systems, settling and service tanks prior to change-over.
– Initial high sulphur level and LSFO level.
– Transfer pumps capacity.
– Separators capacity versus total consumption.

Cylinder lube oil
Oil and engine manufacturers have varying requirements and recommendations. In general there are two alternatives related to cylinder lube oil during LSFO operation:
– Feed-rate regulation.
– Change of cylinder lube oil.

Some shipowners have flagged their intention to continue operating with TBN 70 cylinder lube oil at LSFO down to 1 per cent, by feed-rate regulation, provided not already on the limit. This alternative also appears to be supported by engine manufacturers, provided the operation on LSFO is limited to approximately 1-2 weeks.

There are, however, examples of shipowners who have operated with reduced feed rate on South American LSFO for instance down to 0.5 per cent over approximately a month without experiencing any excessive deposits or wear.

However, some owners have decided to make modifications on board and install redundant service tanks: one for TBN 70 and one for TBN 40/50 with a three-way switch-over valve in-between.

Regardless of alternative chosen, it is recommended that the crew perform periodical checks of cylinder condition (including ring-pack) shortly after change-over. As always, the quality of the cylinder lube oil regarding thermal stability, detergency and dispersion is also essential.

Abatement technology (exhaust gas cleaning)
Recent developments are encouraging, as at least three concepts are now in a prototype test stage either on board ships or on test beds. At least two of these prototype concepts have shown very promising results. Some manufacturers have shown increasing interest in the commercial feasibility of exhaust gas cleaning concepts. Needless to say, it will be some time before they are commercially available.

One additional challenge is future requirements (particularly EU and US requirements) for handling of waste water from such units before discharge to sea.

Although the investment is high, exhaust gas cleaning systems have the advantage of eliminating the LSFO premiums as well as bunker management complexity. Further, they will reduce the particulate matter in the exhaust, for which new legislation is coming soon.


Gard News 184, November 2006/January 2007

Any comments to this article can be e-mailed to the Gard News Editor.

Gard News is published quarterly by Gard AS, Arendal, Norway.