Ship fuels: Training, sampling, storage and switching

Malcolm Latarche

Malcolm Latarche · 12 August 2017


Because fuels are the energy source for ships it is vital that engineers are fully conversant with the hazards, problems and routine operations associated with them. Surprisingly in the past this has not been fully addressed in STCW so there has been no requirement for crew to undergo any formal training in bunkering. Most of the small-scale pollution events in shipping occur as a consequence of mistakes during bunkering so this is an issue that needs addressing but crew must also be aware of all aspects of bunkering relating to quality and quantity delivered.

Although there is no formal requirement under STCW, there are training courses available to attend and also training films on the subject. In addition, organisations such as class societies and P&I clubs frequently disseminate advice on the matter. Over the last year or so, the absence of training requirements has been recognised by the International Bunker Industry Association (IBIA).

In April 2016, IBIA joined with UK-based South Shields Marine School at South Tyneside College, to develop a course unit on bunkering essentials for merchant navy cadets and engineering officers taking their Class one and Class two certificates of competency. The course aims to explain the fundamentals of the bunker industry, the key regulations affecting shipping today, along with the latest industry challenges and developments.

IBIA has plans to extend the course to other colleges in the UK, and then to other maritime colleges around the world. A new category of IBIA membership at a reduced cost specifically for students has also been launched. The organisation is also developing a broader training programme for shipping companies designed to increase on-board competency in handling bunkering and fuel switching.

Perhaps because of its unique characteristics, LNG bunkering has received some attention from the IMO and under the IGF which came into effect in January 2017, some new requirements have been incorporated into STCW. Handling LNG fuel and other low-flashpoint fuels on ships along with rules for specific equipment training and operations on LNG-fuelled ships including bunkering operations and some aspects of LNG-terminal operations are now mandatory for officers and crew serving on gas-fuelled ships.

To advance their careers, seafarers must have at least one month of approved seagoing service to include a minimum three bunkering operations of which two could be replaced by simulator training of bunkering operations.

During delivery of bunkers samples should be taken for analysis in case of dispute and also for compliance with IMO rules. The samples should be properly labelled and stored safely on board. Because of some highly publicised cases of contaminated bunkers causing damage to engines, some operators have adopted the habit of having all fuel analyses before use.

There are many independent laboratories who offer such services and some of the leading classification societies also have their own fuel testing programmes. If taking advantage of such a service, the method sampling will be determined by the service provider. It is also good practice to segregate the new fuel and where possible not use it until the result of the sample analysis is available.

It is to be hoped that most bunker suppliers are honest but there are far too many cases of fraudulent means of short delivering and delivering off spec and contaminated fuels recorded each year to demonstrate that not all are. The contamination cases are sometimes accidental but there are many documented cases of bunker fuel being used as a medium for disposing of hazardous waste chemicals.

Sadly it is also true that some seafarers are also dishonest and willing accomplices in defrauding shipowners by taking bribes to sign false delivery notes. If the vessel is on time charter when such crimes are committed, the owner may not be financially out of pocket by virtue of the short delivery but may find himself on the end of a legal dispute over consumption and performance claims from the charterer.

The advent of Monitoring, Reporting and Verification (MRV) by the IMO and the EU as a means of initially measuring CO2 emissions but potentially as a charging basis for a future market-based measure on shipping is another reason why accurate records of quantities delivered is gaining added importance beyond the commercial considerations alone.

Getting what’s been paid for

Getting what you (or a time charterer) paid for is not as easy as may be expected because of a variety of accidental and deliberate reasons, the latter being more common than they should be. In some parts of the world, having a bunker surveyor in attendance during bunkering operations may well prove to be highly cost effective saving more than the cost of employment and assisting in identifying which bunker suppliers and barge crews can be relied on.

One of the main causes of short deliveries is a failure to recognise or understand the relationship between temperature, volume and mass. Unlike fuelling motor vehicles ashore where volume is the pricing factor, bunkers for ships are almost ordered by mass (tonnage). However, measuring the ordered quantity on delivery is done by volume taking into account the temperature of the fuel. Fuel expands as temperature increases so for the same mass of fuel, the volume will be more at a higher fuel temperature than at a lower fuel temperature. Bunker delivery notes (BDNs) usually detail both mass and volume but whenever there is any doubt as to the actual quantity delivered, the engineer officer signing for the fuel should always endorse it as being for ‘volume only’ adding a clause along the lines of ‘actual weight to be determined after testing of representative samples’.

Any question as to the temperature of the fuel also needs to be remarked upon as this will be crucial to determining actual mass. The temperature is often measured on the barge which may make checking difficult but whenever possible the temperature should be seen by a crew member or temperatures of the ships’ bunker tanks taken at intervals immediately before, during and immediately after the bunkering operation,

One (usually) deliberate means of bunker suppliers making short deliveries is to pump air into the bunker flow during delivery. This causes the fuel to froth, fooling some types of flow meters into measuring a higher amount of fuel. The frothiness of the fuel has given this practice the nickname of ‘Cappuccino Effect’. Not only does the effect give false flow meter readings it can also mean that measurements taken by sounding the bunker tanks are inaccurate, at least until all the air dissipates. The shortage in delivered quantities can be significant ranging from 2% to 5% or more.

There are several ways in which air may be introduced into fuel oil:

  • The bunker barge may inject compressed air into its tanks prior to joint soundings being taken to increase the apparent volume of the fuel oil before it is transferred.
  • Compressed air may be injected into the fuel oil during the transfer, either in the vicinity of the discharge pump, or into the tank or into the discharge line. This may be by using the compressed air equipment designed to blow through the pipelines after discharge, or via a separate system.
  • The stripping of bunker tanks using a positive displacement pump means that air will be drawn into the fuel oil when pumped. Consequently, excessive stripping by the bunker barge may also result in the “cappuccino effect”.

Preventing a short delivery through the cappuccino effect requires vigilance by the crew during bunkering but there are several signs and sounds that are giveaways that something is amiss. These include:-

  • Suspect connections on the bunker barge’s supply pump and pipework – these can be quite small as only compressed air is being injected.
  • Check the manifold sampling point at regular intervals for frothing or excessive air bubbles.
  • Look for foam and/or frothing on the surface of the fuel oil on the barge prior to bunkering, and on the vessel while bunkering is taking place and on completion.
  • Check for bubbles on sounding tapes
  • Unusual noises at the manifold, supply line or fuel tank vent head.
  • Unusual movement of the supply hose during bunkering
  • Fuel density – if too low for temperature may indicate presence of excess air. The temperature of the fuel oil should be measured before the transfer takes place so that the fuel oil density can be calculated accurately.

If it is suspected that air may have been introduced into the fuel oil, an engineer should board the bunker barge and ask to see the line blowing arrangements and the air compressor. If these have recently been in use, the compressor and its connections will be warm, while the compressed air delivery line will be cold. Empty compressed air bottles may also provide an indication that the fuel oil has been injected with air.

The Cappuccino effect cannot be detected by most types of flow meter but mass flow meters (MFMs) using a device known as a Coriolis meter are much more accurate as they do measure mass rather than volume. Because of several problems with bunker suppliers using the method to defraud shipowners, the Port of Singapore introduced a requirement for all bunker barges in the port to use MFMs with effect from January 2017. Other major bunkering ports such as Rotterdam are investigating the need for similar regulations.

Very few ships have been fitted with MFMs but they are available and one manufacturer – Krohne Skarpenord based in Norway – has produced a system known as EcoMATE which includes a MFMs and associated software to both more accurately measure fuel supplied and consumption on board as well as meeting the requirements of MRV regulations.

Although they are more accurate, MFMs are not infallible and can be cheated. In mid-March 2017, the Maritme and Port Authority of Singapore (MPA) temporarily suspended the licences of five Panoil Petroleum bunker tankers equipped with MFMs citing “irregularities” with the vessels' piping fixtures although MPA did say that the integrity of the MFMs remained intact.

Following the suspension, the North of England P&I Club advised its members detailing a possible reason for the suspension and highlighting an issue that may exist with some MFMs. According to the club, one implication of piping fixture irregularities may be that they allow some quantity of bunkers to be siphoned back into the bunker tanker tanks whilst bunkering is in progress. This would mean that the amount registered on the MFM totalizer is greater than that delivered to the vessel, with the vessel receiving less than that recorded. Piping fixtures form an integral part of the MFM system, as specified in the Technical Reference for Bunker Mass Flow Metering (TR48). One of the roles of the bunker surveyor is to check the integrity of this system.

Since 1 January 2017, the figure on the BDN presented to the vessel in Singapore is the figure obtained from the MFM. Bunker barges do not accept figures derived after calculating quantity received on board from soundings, nor do they participate in the sounding process. However, the club advise that ‘Soundings should still be taken on board before and after bunker delivery and, in case of a difference between the vessel figures and the BDN, letters of protest should be issued’.

The club also said that while bunker suppliers will not usually accept these letters of protest or will refuse to sign them, in the event of a dispute, they are evidence to show a difference between the MFM figure and the figure obtained by the sounding method. Charterers should be informed of any difference immediately. The use of a reputable bunker surveyor who can inspect the bunker barge lines for any irregularities in addition to cross checking the seal verification report, inspecting the seals and taking MFM readings, is recommended.

Dilution of fuel

Under the ISO 8217 standards, the water content of most residual fuels is limited to 0.5% v/v and in most cases is usually considerably below this level. However, fuel can sometimes contain higher levels as a result of an accident such as a leaking heating coil or as a consequence of fraudulent and deliberate injection of water.

If samples indicate a high level of water beyond that allowed by the ISO 8217 standard, then a letter of protest should be issued. The ship’s fuel treatment system should be able to remove water but if this is not the case then the fuel may have to be landed ashore. Fuel samples provided by the barge may not have any traces of water as the samples may have been taken prior to bunkering and mixing of water. Fuel samples should always be collected during bunkering and not before or after. Samples should only be signed for those actually witnessed. Use of water-finding paste on the sounding tape works with distillate but not with residual fuels.

More grades more problems

The advent of ECAs not only means that a shipowner without a scrubber is obliged to burn more expensive fuels but also those fuels need to be segregated. Therefore it is necessary to have different storage, settling and service tanks for each grade of fuel. This can be provided for in new buildings easily enough but for existing vessels the choice may come down to running all the time on more expensive fuels or else having existing tanks divided during a dry docking to allow for the extra number of tanks needed.

Even where ships have a number of bunker tanks available, using two or more different grades of fuel may make management extremely difficult. This is particularly true when the size of individual tanks means that only relatively large volumes can be allocated to low-sulphur fuels. The low-sulphur product attracts a premium price and so will undoubtedly be used only when mandated – unless the ship operator has unusually high environmental ideals.

Reserving a large space for LSFO – even it is the minimum possible – will inevitably mean that space for standard fuel is reduced. That may not present a problem for vessels that make relatively short ocean voyages, but it will mean that on the occasions when standard bunker fuel can be had at attractive prices, not all the tank space will be available for it.

Blended fuels

As demand for low sulphur fuels has increased, the availability of inherently low-sulphur crude oil stock has not kept pace. As a consequence much of the low-sulphur fuel on the market is a result of blending fuels with different sulphur contents to make one with the appropriate level of sulphur. Often the viscosities and other characteristics of the fuels blended are very different and this can lead to problems further down the line. It is not unknown for blended fuels to separate out in a ship’s tanks or to become unstable when mixed with other fuel during subsequent bunkering operations.

If a blended fuel separates it is possible that the ship will at some point be burning fuel that exceeds the sulphur limit permitted by MARPOL. This could lead to a ship being detained or penalised by an unsympathetic port state. Connect with this issue is the interpretation of MARPOL regulations where limits on sulphur are set to a single decimal point and the question of whether rounding down is permitted where a fuel may have a sulphur content very slightly above that show in MARPOL.

Blended fuels may also have very poor ignition characteristics causing fouling of cylinders, turbochargers and exhaust systems and in worst case scenarios engine failure and power blackout. Such problems are most likely to occur during switch over between standard and low-sulphur fuels which usually takes place as vessels are entering areas of heavy traffic and thus increasing the risk of collision or worse.

Switch over

Now that the two North American ECAs are in operation along with the North Sea and Baltic Sea SECAs and the EU and China have regional regulations on using ultra low-sulphur fuel in ports, the number of engineers having to deal with switch overs between fuels is growing but is far from being universal.

Many ships not subject to mandatory low-sulphur fuel limits already switch from HFO to marine diesel oil (MDO) during port operations, so the procedure is not entirely alien, but in SECAs there is a burden of proof upon the ship to show that at the point of entry into the controlled zone it was burning only the permitted fuels.

That involves a gradual changeover and if the switch is from ordinary HFO to low-sulphur HFO there will be a need for the temperature of the low-sulphur product to be managed so that a smooth switch can be achieved. Even so, the time taken to achieve compliance will depend upon the amount of fuel contained in the system and the tank space available for service fuel.
Because heavy residual fuels will be used at temperatures above the flashpoint of low-sulphur distillates, when the switch involves these types of product the temperature in the fuel lines must be monitored and managed with great care. This is especially true if the engine makers require the residual fuel to have a particular viscosity which may involve cooling it below ambient temperature.

Class societies and industry organisations have offered a lot of advice on this subject, even going to the extent of preparing comprehensive manuals and guidelines for operators. Just how extended the time to achieve changeover can be, is amply illustrated in one of the DNV GL guides. Based on a switch from a world-average 2.8% sulphur content fuel to a desired level of 1.3% on a vessel where the fuel oil system contains one service tank and one settling tank each of which contains sufficient fuel for 12 hours of operation, and taking into account a further one hour’s supply of fuel remaining in the piping system, the changeover time will be around 60 hours.

That could be reduced by minimising the service and settling tank contents prior to changeover to LSFO. DNV GL, however, recommends that the service tank contain enough fuel oil for continuous rating of the propulsion plant and normal operating load at sea of the generator plant for a safe period of eight hours. The changeover time under such circumstances would then be cut to around 21.6 hours.

Managing switching by machine

There are alternatives to managing the switch between fuels manually with at least four automatic systems available. Two of the products share the same name – Diesel Switch with one being offered by MAN Diesel & Turbo and the other by Aquametro and Jowa. The third is Auramarine’s Fuel Selector and the last is a relative newcomer and was introduced in 2013 by Danish company Insatech and labelled as the S3 Smart Sulphur Switch. For a manual change, MAN Diesel & Turbo recommends crew to reduce engine loads to 25-40% before changing fuel type, the Diesel Switch retrofit enables a controlled and safe changeover independent of engine load. It does this through continuously checking temperature versus time. If the fuel temperature at the engine inlet exceeds 2 degrees/minute, the Diesel Switch emits an alarm and automatically halts the changeover process.

The Diesel Switch also logs the entire changeover process for subsequent use as official documentation for port authorities if required. The device’s hardware is controlled by a touch-screen control panel and has software to operate an MGO cooler to adjust fuel temperatures. The changeover valve uses magnetic couples that dispense with mechanical seals and are 100% leak-proof. It also has integrated sensors for detecting current and end positions. As back-up, the entire system has a manual override.

All of the other systems can also control onboard blending of fuels as well as managing the changeover. The S3 Smart Sulphur Switch costs around €140,000 and is aimed at ships where fitting a scrubber might be uneconomical. The unit permits HFO and MGO to be blended, offering what is claimed to be an optimum balance between cost and sulphur emissions.

As with some of the other devices, full details of the switch between fuels including time and location (taken from the ship’s GPS) is recorded and can even be transmitted ashore using the ship’s communication system. Running costs for the S3 are said to be less than 0.1% of the cost of running a scrubber. The unit is supplied on a skid mounting and requires only connection of HFO and MGO lines, and a line for the blended fuel discharge, plus a standard electrical power plug.

Choices and charterers

As possibly the highest of all operating costs, fuel and lube purchases need to be subject to proper oversight. When a ship is operated for the owner’s own account, control of choice of fuel and its suitability is clearly a matter for the owner but when time chartered out fuel supply is taken over by the time charterer. Lubricants almost always stay within the control of the owner or ship manager.

Regardless of the time charterer’s status, the operator should always ensure that full details of acceptable fuel grades are included in the charter party. While the time charterer will normally consult with the ship’s officers on quantities of fuel needed for particular voyages the choice of supplier and actual grade ordered is out of the ship’s control and it often happens that the time charterer orders the cheapest fuel available even though it may not be in accordance with the quality criteria in the charter party. If that happens, the master should seek advice from his owner but the concerns of the technical staff are sometimes ignored by management especially in times when employment for vessels is hard to find.

It is vital that any problems with supplied fuel are brought to the charterer’s attention because in the event that a problem occurs that causes an offshore situation there will be no recourse for the owner if the charterer can plead ignorance of the consequences of using inadequate fuel.

Another problem that is frequently encountered when vessels are time chartered is when the time charterer hits financial difficulties and does not pay all outstanding costs incurred. Far too many owners have been caught in this situation and the legal consequences are that they become responsible for most if not all of the unpaid debts. There are clauses that can be inserted in charter parties that seek to minimise the risk but these are not always helpful or enforceable. One such clause is the BIMCO Bunker Non-Lien Clause for Time Charter Parties which provides a good example of the practices that owners should adopt.

Finance risks of bunkering

There are many ways of purchasing bunkers with some operators choosing to deal directly with suppliers while others prefer to make use of the services of a bunker broker. Some suppliers and brokers offer arrangements such as fixed price agreements that operators can make use of to reduce the volatility in prices that bunkers are prone to. Alternatively there are many financial institutions that offer hedging arrangements. Whether financial instruments are appropriate options is for individual operators to decide but there is always an element of risk that has to be taken into account and since the institutions are not charities there is a premium that will need to be considered as well.

When making use of a broker for bunker supplies, operators should be aware that while most transactions will be without risk it is not unknown for brokers to have financial problems and since they are not the physical supplier of the fuel, the operator could be exposed to double payment or arrest if the broker does not pass on payments to the supplier. The most recent case of this involved Singapore-based Dynamic Oil Trading, a subsidiary of Danish firm OW Bunker.

A large number of legal cases and the bankruptcy of the parent company have followed with many suppliers, shipowners and intermediaries faced with massive payments and legal expenses. The cases have been held in different jurisdictions with conflicting results that have done little to establish precedents for the shipping industry.

The Journal

Published every February the journal is now recognised as the highest quality publication that covers all aspects of maritime technology and regulation and a must read for the industry.

More Details