Q&A: Ensure that marine systems can operate on diesel

Naeem Javaid is the global operations manager at UK-based maritime classification society Lloyd's Register's Fuel Oil Bunkering Analysis and Advisory Service. Javaid is also a member of the International Bunker Industry Association and has actively contributed to the development of the latest 2017 International Organization for Standradization (ISO) marine fuel standard. In this Q&amp;A, edited for length and clarity, Javaid discusses what the industry can expect from ISO's 2020 marine fuel specifications, some of the challenges shipowners could face with the various fuel specifications, as well as the specifications Lloyd's Register has encountered when testing 0.50pc sulphur marine fuel already sold in China and Singapore.

What guidance can we expect from the industry marine fuel working groups and the International Organization for Standardization (ISO) to address the use of the max 0.50pc sulphur fuel oils in 2020?

ISO considered that a revision of the existing specification guidance ISO 8217:2017 was not possible prior to 2020 because of the 0.50pc sulphur marine fuels future implementation date and because these products were not widely available on the market at the time to obtain a full scope of the fuels that would be offered.

But ISO initiated the process to develop a publicly available specification (PAS) 23263 "Considerations for fuel suppliers and users regarding marine fuel quality in view of the implementation of maximum 0.50pc sulphur in 2020". PAS, which is expected to be published this month, is to be used in conjunction with the existing marine fuel specifications last updated in 2017 or with earlier editions.

The PAS will provide general considerations for 0.50pc sulphur fuels, including flash point, kinematic viscosity and cold flow properties. The PAS will also provide, through Annexes, further clarifications and considerations on fuel stability, composition of fuels, additional information on harmful materials, commingling of fuels including information on pre-delivery compatibility testing and on other test methods which can be used to evaluate stability and compatibility of fuels.

There will not be any additional tables for 0.50pc sulphur fuels introduced into this PAS, because the current ISO 8217:2017 specification will provide the necessary coverage for all marine fuels going into 2020.

ISO has engaged the International Council on Combustion Engines (CIMAC) working group 7 (WG 7) which is comprised of cross industry specialists within marine fuels, represented by engine manufacturers, shipowners, classification societies and fuel suppliers. Their goal is to prepare recommendations and make tools for the industry on how to operate on fuel, and choose fuels that will ensure safe operation of the diesel engines. In support of the ISO PAS, CIMAC WG7 will be publishing two practical guides: "Marine fuel handling in connection to stability and compatibility" and the "How to order and Manage conventional fuel in the market towards and beyond 2020".

China has already implemented 0.50pc sulphur emissions control zones. In addition there are ships burning 0.50pc sulphur fuel for sea trials. What stands out about their specifications, compared with conventional RMG 3.50pc sulphur 380 centistokes (cst) viscosity bunkers?

Yes, we are seeing an increase in 0.50pc sulphur fuel samples being tested at our laboratories from around the globe but more specifically from China and Singapore. The one aspect of the fuel characteristics from a single ordering specification of RMG 380cst 0.50pc sulphur maximum fuel is the marked variances in viscosity and density along with the associated tested elements. For viscosity, we are seeing from China 10cst to 420cst (at 50°C) and from Singapore the fuels tested so far have viscosity ranging from 100cst to 380cst. Densities also vary considerably, ranging from 0.840 kg/l to 0.991 kg/l at 15°C. We also saw average pour point has increased and now 0.50pc sulphur fuel oils have pour points closer to the maximum allowable limit of 30°C and sometimes higher. Ignition characteristics which are denoted by calculated carbon aromaticity index (CCAI) have also been very variable throughout the 0.50pc sulphur fuel oils supplied, so far ranging from 780 to 870.

Fuel oils with 3.50pc sulphur and 0.50pc sulphur have different consistencies. Do you foresee problems such as low viscosity causing pump failures and leakages due to low viscosity and low lubricity?

The variance in viscosities could be a challenge if ships have not made the necessary preparations, for example checking the ship's adaptability to such anticipated variances of the 0.50pc sulphur fuel oil characteristics. Full adaptability will require the maximum range of capability from the high heat to the low cooling of a 0.50pc sulphur fuel oil. This is not much different to today for ships operating in the Emission Control Areas (ECAs), which require switching from residual marine to distillate marine fuels.

The question that needs to be answered by all ships operating on residual marine fuels: how adaptable is my ship to the variability of 0.50pc sulphur fuel oil? Either ship constraints should be highlighted, or the fuel system arrangements duly modified to accommodate. We would expect ships to have considered the 0.50pc sulphur fuel oil bunkering scenarios as part of the IMO recommended Ship Implementation Plan (SIP) to ready their fuel system and machinery plants accordingly.

ISO 8217:2017 has maximum viscosity for residual fuel oil bunker grades, but not minimum viscosity. Should ships be considering a minimum viscosity requirement?

The quick answer is yes, ships should identify for each combustion plant and fuel system component arrangement what the minimum viscosity for safe operation is and for the most part this is 2cst.

However general recommendations are to keep it above 3cst as a safer margin accommodating for higher ambient temperatures. Each system should be assessed individually, for example some main boiler residual marine systems set a minimum limit of 180cst. Any constraints in this area should be considered when making the fuel ordering specification.

There are two issues: storage and handling, and if viscosity is low and heating cannot be stopped completely, some older fuel transfer pumps may not be able to transfer the fuels effectively. Similarly, the purifier temperatures will require fuel temperatures to be set according to the manufacturer's recommendations.

The viscosity controller should be checked and maintained to ensure injection viscosities are maintained to specified engine requirements. Attention should be given to lower viscosity fuels to ensure that they are not overheated.

In some scenarios the higher temperature requirement the purifiers bring may require some cooling of the fuel to achieve the optimum injection viscosity.

There is high probability of paraffinic fuel oils making their way into the marine bunker market, which will not only increase the need to address higher pour points but also the general cold flow properties of fuels. What can the shipowners do to protect themselves?

It is important carry out a 0.50pc sulphur fuel oil scenarios risk assessment of the fuel system against the specific core operational parameters of a fuel, these being the viscosity, density and cold flow properties of the fuel delivered. The outcome of which should include: knowledge of the specific characteristics of the fuel as loaded will therefore be critical to ensure correct management for storage handling and use.

The outcome of the risk assessment should ensure that: all residual marine fuel storage tanks can maintain 45°C to cover pour points that might reach the ISO 8217 limit of 30°C and requiring a check on steam capacity during slow steaming conditions. The distillate marine fuel storage and supply system may be heated to address when wax crystals may form as high as 30°C in some cases but for the most part around 17°C, requiring fuel temperatures to be able to be maintained at 20°C and in some cases 30°C.

If there is no heating capability for the distillate marine system, then the bunker order clause should reflect a request for information from the typical cold flow properties of a fuel to be supplied as per ISO 8217:2017.

We suggest planning for bunkers ahead of time as it gives the flexibility in choosing bunkering ports/stems and suppliers.

Should shipowners consider changing their bunkering and fuel testing procedures to better protect themselves from 0.50pc sulphur fuel oil-caused engine problems? If so, what procedures would you advise? Should shipowners run additional specification tests to the standard specifications test they already run? If so what are they and how long does it take to get the results? Should shipowners be testing for catfines? If so is this a standard test?

The IMO has recommended that ships should have a specific Ship Implementation Plan (SIP) in place to cover all aspects of the switch over from high-sulphur to low-sulphur fuel oil. This covers bunkering through to using on machinery fitted on board to ensure compliance by 1 January 2020.

For testing, existing tests as per ISO 8217 is sufficient for most ship's requirements, but if there are any specific operational limitations or concerns about a product or even a supplier, additional and investigative testing/screening may be requested to be carried out. It should be noted that switch over to 0.50pc sulphur fuel oil is more of an operational challenge than fuel quality one. The point to note about fuel quality and that its expected variance of the known parameters and therefore, safe use of these fuels, depends on the readiness of ships.

If a shipowner is planning to mix 0.50pc sulphur fuel oil from two different suppliers in the vessel's bunker tank, what is the lowest level of fuel compatibility they could tolerate without jeopardizing their vessel? How long does it take to run a compatibility test?

The first policy widely recommended is to avoid mixing fuels, in other words, segregate fuels. Plan to load into empty storage tanks only. In the event this cannot happen, and the operator has no choice, then it very much depends on the makeup of the two fuels to be mixed.

The outcome is difficult to predict without physically testing. If the two fuels are incompatible, then mixing such fuels can create an unstable blend causing heavy sludging in the tank bottoms leading to other critical operational problems. In some extreme cases, the only solution is to manually dig the fuel out of the storage tanks. It is therefore not worth taking the risk of mixing fuels without having the compatibility between the two fuels determined.

The compatibility Spot test ASTM D4740, which can be carried out on board, takes no longer than an hour and the result must not exceed a rating of two. A result from three to five will indicate the two fuels are incompatible. For any intended mixing we suggest that mixing of fuels should not take place in excess of 5:95 ratio without determining the compatibility of the two fuels. This can be done through analysis and considering both ratios of such as 10:90 and 90:10. A fuel filled on top of another fuel could make a difference to the outcome of the spot test analysis. In addition, a 50:50 ratio should be tested to add a more complete understanding of the behaviours of the two fuels.

For vessels that cannot procure 0.50pc sulphur fuel oil at the port they are bunkering, and they are offered only a distillate marine product to burn in their main engines, what problems do you foresee? What are the lessons learned from 2015, when the Emission Control Areas (ECAs) switched to 0.10pc sulphur from 1pc sulphur fuel?

Ships should be prepared to fill their 0.50pc sulphur fuel tanks with a distillate marine maximum 0.50pc sulphur fuel oil. This should have been considered in their ship implementation planning, which would result in assessing the adaptability of the ship for such a scenario.

The key concern here is to understand the significance of storing, handling and operation on a low viscosity distillate marine fuel requiring little or no heating in a residual marine heated fuel system, designed for higher viscosity fuels. It all depends on the readiness of ships and whether they have been sailing in and out of ECAs. Those ships which have been sailing in an ECA for extended time periods with experience of using distillate marine grades on their main engines are not expected to face problems as those ships are usually prepared and their fuel system and machinery configuration already allows them to operate on gas oils for extended periods.

The ships without this experience should consider steps, for example having a good control on their tanks heating system to avoid overheating where such fuels are loaded into residual marine tanks. Any limitation on transfer pump capacity to pump low viscosity fuels should be evaluated. Similarly, the injection temperature needs to be controlled to ensure fuel viscosity remains within the original equipment manufacturer guidelines.

Diesel marine fuel oils will generally have a cleaning, searching action when used in systems which generally operate on residual fuel oils. This will have the effect of potentially mobilising accumulated sludge materials with consequent increased loading on the fuel treatment equipment or sticking of fuel injection components.

Additionally, due to the "searching" nature of these fuels, seals and joints may exhibit a tendency for leakage, an effect which would be compounded by component temperature variations resulting from switching between fuel types. There would also be an increased tendency to dribble from fuel injectors.

For engines, it is important to ensure the maintenance condition is good to avoid excessive leakage of gas oil from fuel injection equipment which could lead to the reduced or complete loss of power, impacting the safe navigation of the vessel. Similarly, boiler manufacturers should be contacted for guidance on regular use of low viscosity fuels and the implications of a distillate fuel oil passing through residual marine heated fuel system, with a focus on the boiler fuel supply circuits for both auxiliary and main engines as applicable.

Do you foresee engine problems when shipowners switch from burning 0.50pc sulphur fuel oil in the open seas to burning 0.10pc sulphur marine gasoil at the ports or in the ECAs?

In general, assuming a consistent fuel quality, we do not expect many issues when switching over from 0.50pc sulphur to 0.10pc sulphur fuel oil. However, the real issue will be the variability of 0.50pc sulphur fuel oil which will make switchover to gasoil more complex. But if ships are otherwise using gasoils in the ECA we do not expect any additional issues arising out of switch over from 0.50pc sulphur to 0.10pc sulphur fuel oil, when compared to switch over from 3.50pc sulphur to 0.10pc sulphur fuel oil.

What is the stability test method you would recommend to shipowners bunkering 0.50pc sulphur fuel oil. How long does it take to run it?

A Potential Total Sediment Test (ISO 10307-1) is included in the ISO 8217 specifications and we will continue to do this for 0.50pc sulphur fuel oil. If shipowners want additional understanding of the stability and potential compatibility of fuels, then there are further testing options available. The CIMAC guidance document on stability and compatibility is being worked on and should be available in September. It will detail the shipowners options in supplement ISO/PAS 23263:2019.

Has the bunker contamination problem from the spring and summer of 2018 in the US Gulf, Singapore and Panama changed the way shipowners bunker fuel and test the fuel?

The widespread fuel related operational issues originating from US Gulf and then to Panama and Singapore, have heightened the awareness of these issues among shipowners, in way of the risk of abnormal chemical species, its testing and its impact on machinery and vessel operations.

Owners have taken multiple approaches in reviewing their bunkering strategies which includes: being more specific about the selection of suppliers, additional checks on quality testing, setting tighter bunker quality requirements, additions to the bunker requisition clause and seeking further assurances from suppliers.

Testing all fuels for extended analysis is generally not a financially practical option and does not necessarily provide the result from which the performance of the fuel can easily be predicted. But there is an increasing trend of ship operators interested in quick screening to check whether the fuel is free from some of the more abnormal presence of chemical species not anticipated to be found in the petroleum hydrocarbon stream.

What is a key point to remember with regards to 2020 regulation compliant marine fuels?

Ensure that your residual marine fuel system and the combustion plants are adaptable to operating on diesel marine fuels, in way of the likely variabilities between each bunker on viscosity density and cold flow properties.

Vessel crew awareness and preparation through SIPs is fundamental.

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