The consequences of bunker shortage or off-specification bunkers can be very severe. A lower quality bunker supply can lead to ship engine failure, incur loss-time, and additional expenses for refueling. In many parts of the world, greedy bunker suppliers make tricks to supply less. Both this situation not only increases the financial burden of a shipowner but also damages business reputation. Some critical considerations, therefore, need to be made for a safe bunkering operation.
A prudent chief engineer should keep a proper record of all bunkering events for future reference. To avoid fuel quality and quantity disputes, we have summarized below some guidelines that are standard for all cargo ship types.
The Bunker Delivery Note should be retained by the chief engineer on board three years after the bunkering. He should enter the bunkering time, type of FO, volume of FO, and sulfur content, in the engine logbook and the oil record book.
Bunker fuel quantity and quality claims can be minimized if correct procedures are followed, as explained below.
First of all, it is crucial to segregate new bunkers from pre-existing fuel.
Loading into empty tanks can resolve incompatibility problems, make measurements easier and
reduce the chance of spills.Before delivery, the vessel's bunker tanks should be measured.
Densities and correct petroleum tables should be used to convert observed volumes to volumes at standard temperature.
All findings should be recorded. A bunker loading plan comprising all tank measurements should be prepared before the delivery and expected tank contents on completion of taking bunkers.
Always check that the bunker delivery note shows the type of fuel and quantity intended for delivery is as expected.
Bunker delivery note or sample labels should not be signed before the delivery.
The barge should be attended to in the company of the barge master, who should measure and record the contents of all the cargo tanks, including any not designated for your delivery.
The temperature of the fuel should be taken in all the tanks.
Signs of foam on the fuel surface or excessive bubbles on the sounding tape should be identified. It may indicate that air has been blown into the fuel.
The chief engineer should check that the barge calibration tables have an official certification stamp.
If not, a letter of protest should be issued.
If the C/E is not convinced that the tables are correct, an independent surveyor should be called immediately.
Bunkering operation
If bunkering in the U.S.A., the record of the onboard meeting/training, testing of equipment and Pre-transfer Conference shall be entered in the deck logbook as follows: -
Conducted the training for all crew members who assist in the bunkering operation.
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Inspected oil transfer equipment and systems according to 33 CFR 156.170 and found them in good order.
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Pre-transfer Conference took place with the person in charge of the bunker barge / supplier.
The Chief Engineer should keep the following documents on board for one year as the record of the practice of bunkering work:-
A copy of the telex (or facsimile) of the bunkering notice from the Fuel Section (or agent).
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The Bunkering plan prepared by the vessel.
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Tank sounding records taken during bunkering and data for refueling volume calculation (A memo used on the spot may be accepted as it is).
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The Check List for Bunkering operation which has been filled in.
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The list of personnel who have been engaged in the FO transferring operation.
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The Check List for open/closed condition of refueling-related valves has been filled in.
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The confirmation letters for oil leakage prevention (when refueled in Japan).
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The Declaration of Inspection (when refueled in the U.S.).
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Pre-transfer OSRO Notification (when refueled in California, U.S.)
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If confirmation letters of inspection for oil leakage prevention or similar documents are exchanged, the copy of such documents (when refueled in countries other than Japan and the U.S.).
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The bunker receipt duplicate.
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Chief Engineers reports on receiving FO or on other abnormalities and a copy of the Company instruction (if any).
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A copy of the protest letter to a bunker shortage (if any).
Fuel oil delivery: quantity
One method of adjusting the delivered quantity of fuel oil is by measuring twice. It is done
by transferring the fuel from one tank to another by gravity. One of the first tank quantities measured is then dropped under gravity to an available slack tank, which will be measured last. Usually, this is achieved by transferring
from a fuel tank aft to a slack tank forward, the gauging having been started in the aft tanks.
Countermeasure - re-check the first tanks measured before delivery begins.
Ullage and soundings
The delivery barge contends that seals on sounding and ullage pipes cannot be broken.
The deceit is usually backed by pretexts such as Customs seals or a seized sounding cock.
Usually the only alternative to gauging the tanks is by measurement through a flowmeter.
Be wary of air being introduced through the meter to increase the measured delivery
displayed. It is commonly called the "cappuccino effect" (see below).
Countermeasures - do not agree to meter only fuel oil deliveries. If Customs seals
are cited, issue a letter of protest, or comment on the bunker delivery receipt with
counter-signature from barge master.
Flowmeter readings
Sometimes bunker barge flowmeters are fitted with a small bleed-off line after the flowmeter
that returns the fuel being bunkered to the suction side of the barge bunker supply pump.
It effectively means that the fuel is being passed through the flowmeter twice. The by-pass
recirculation line may only be small in diameter but over the bunkering period, can have a
big impact on the quantity of fuel bunkered.
Countermeasures- check for any suspicious lines after the barges flowmeter. Use the
ship's flowmeter (if fitted) as a cross-check and question any significant differences. Ask to see
the bunker barges flowmeter calibration certificate and check that the flowmeter seal is
intact. Refer to the bunker barge cargo piping diagram to assist with the checking of any
suspicious lines.
The cappuccino effect
Air is sometimes intentionally introduced by the supplier during the pumping of bunkers to
the ship, which aerates the fuel being delivered. The common standard type flowmeter will
not measure the quantity of fuel delivered but the volume of throughput. If the fuel has
been aerated, this volume is made up of fuel and small air bubbles.
Thus the quantity of fuel
being delivered is, on some occasions, considerably less than stated, because the flowmeter,
which measures the volume going through it, reacts to both the bunker fuel and the
low-density entrapped air and registers this as a large volume of oil. However, the mass of the
entrapped air is so small that it does not contribute significantly to the mixture's total mass
. When the bunker tanks are sounded, the soundings also appears correct as
the entrapped air is still in suspension in the fuel.
When the air eventually settles out of the
fuel oil, the level of the bunker tank drops. It indicates an apparent onboard fuel loss at
the next sounding. Depending on the number of bunkers requested, the fuel shortage can
be considerable and amount to a heavy financial loss, or result in a bunker claim.
This practice is commonly referred to as the "cappuccino" effect.
Countermeasures- use a density meter to check the density. There are meters available
that can measure the exact quantity of the fuel being delivered. Coriolis meters continuously provide online measurements of mass flow rate, volume flow rate, density, temperature,
and batch totals- all from a single device. Coriolis meters have no moving parts or
obstructions in contact with the fluid being measured and require little maintenance, flow
conditioning, or straight pipe runs. Unlike volume measurement, mass measurement is
independent of operating pressure and temperature, which obviates the need for error-prone
density conversions.
For highly viscous fluids where entrained gas and air is unable to
escape, direct mass flow measurement can perform better than volumetric meters and tank
gauges. The Coriolis meter will give a more accurate measurement of the quantity of fuel oil
delivered. These meters can be expensive and may require system piping modifications.
Combating the cappuccino effect for bunkers
Before loading bunkers from a barge, the following checks should be carried out besides
to the ships bunkering procedure:
- board the bunker barge and verify, by sounding the barges fuel oil cargo tanks and using
corresponding sounding tables, the quantity of fuel onboard the barge before bunkering
commences
- if possible, obtain draft readings of the bunker barge before pumping begins
- check the sounding tape when sounding the fuel tanks on the barge and during
bunkering for any evidence of air bubbles in the fuel
- ask to see the barges cargo pump used for fuel delivery and check for any
suspect air connections. These may be quite small
- ask the crew how they intend to blow the lines after completion of bunkering and ask to
inspect this arrangement before starting fuel transfer, to limit the opportunity to introduce
air with the oil flowing
- check the barges flowmeter reading and confirm that the calibration certificate is for the
the meter in question and is valid. Confirm that the meters calibration seal is intact
- check for suspicious flowmeter recirculation lines. These may be small but can have a big
impact the quantity received onboard during bunkering, monitor every 30 minutes the quality of the fuel coming onboard by
using the bunker sampling point. Check the fuel for any frothing which
is indicative of air entrapment
- if frothing is suspected, board the barge and ask to see the line-blowing arrangement.
If this has been used, it may still be connected, and the compressed air piping after the air
isolation valve may be cold. It may be an indication that it has been recently opened
After completion, board the bunker barge and verify, by sounding the barges fuel oil
cargo tanks and checking the corresponding sounding tables, and calculating the quantity
of fuel remaining on the barge. The difference from initial soundings to final soundings should
give a good indication of the quantity of fuel off-loaded from the barge
- if possible, obtain a reading of the draft of the bunker barge after pumping is complete
- ask to see the barges draft tables and roughly calculate the difference in drafts from
bunker start to bunker completion, and use the table to convert to tonnage. It will give
a rough measure of the quantity of fuel discharged.
List and trim
Sometimes the barge may have a list or trim, and no correction tables are available. It is possible that in these circumstances, the trim or list is to the advantage of the supplier. Therefore, the purported amount of fuel onboard is more than that which exists. The difference
between the apparent and actual fuel oil on board can be considerable, especially if the
tanks have a large free surface area.
Countermeasures- If no trim correction tables are available for inspection before taking
fuel oil delivery or gauging tanks, it may be prudent to make a written comment stating that
"no trim correction tables were sighted". It should be countersigned by the bunker barge master.
Temperature
The temperature of the fuel oil is essential as it affects the volume delivered. If the declared
temperature is lower than the actual temperature, less fuel oil is
delivered. For the supplier, "gaining" a few degrees Centigrade means gaining a few tonnes.
Countermeasures- check and record the temperature during the initial gauging and
periodically until completion.
Calibration tables
It is not unknown for duplicate barge tables to be used. At first glance, these appear to be
in order but modified to the advantage of the supplier. Inserted pages,
photocopies, corrections, different print, and paper types are all indications of tampering.
Countermeasures- check if the tables are original or a copy- issue a letter of protest when in doubt.
Water
If 1,000 tonnes of fuel is bunkered and it contains 1% water, it is effectively just 990 tonnes
of fuel. A loss of 10 tonnes of fuel resulting from water content is a loss of approximately
$7,0004
Water may be mixed with the fuel oil just before the bunkering takes place. "Sealed" samples are taken from the barge before the water is introduced and used as "official."
Supplier samples. Another trick is not using water-detecting paste on the sounding tape.
A water-detecting paste can be used for distillate fuel deliveries but does not work with black
residual fuels as it cannot be seen as the color change. Sometimes an incorrect alternative
paste is used, like chrome cleaner, which looks and smells the same, but does not change
color on contact with water.
It is also possible that the supplier of fuel oil to the bunker barge has given the barge excess
water. It can then be passed on to the customer who will be unaware of water being
present. Bunker barges normally bunker fuel from the port oil terminals. The detection of
excess water depends on the effectiveness of their procedures and checklists.
Saltwater is sometimes delivered with fuels as a result of contamination by the bunker
barge. There are many potential causes, including ballast water contamination,
structural defects, and incorrect valve operation.
A common source of seawater ingress is
ballast water entering the ship's bunker tank via a corroded sounding pipe. One of the main
concerns over seawater contamination of fuel is that a chemical reaction between the
sodium (salt) compounds in the water and the vanadium compounds in the fuel during
combustion may cause high-temperature corrosion (hot end corrosion). The vanadium and
sodium oxidize during combustion, which causes sticky low-melting-point salts adhered to exhaust valves valve seats and turbocharger turbine blades which in turn attract
other combustion deposits leading to mechanical damage.
It should be noted that the ISO 8217:2010 standards state that the maximum allowable
water content for all heavy fuel oils should be not greater than 0.5%.
Excessive water represents a triple loss. Firstly, there is the loss of specific energy in the fuel, which will affect fuel consumption. Secondly, there is the cost of disposing of the water
removed by the treatment system. Such water is unlikely to pass through a 15 PPM oily
water separator, so it has to be retained for disposal later, with a cost to the ship operator.
Thirdly, water will damage fuel injection equipment, cause corrosion and failure
of exhaust valves and turbochargers.
Countermeasures- check using "Water in Oil" test. Issue a letter of protest if the
percentage of water content is more than stated on the bunker delivery receipt.
There are other less sophisticated, underhand methods of reducing the real quantity of
fuel oil delivered. These include "unofficial" piping between the storage tanks and other
un-nominated tanks, such as cofferdams or void spaces.
Countermeasures- fundamentally, the care, diligence, and training of the staff responsible
for fuel oil deliveries. The purchaser should obtain specification acceptance by the fuel supplier.
Summary
- fuel oil purchasers need to advise the ship's staff which grade of fuel they will receive and
how it will be transferred
- fuels from different deliveries should be segregated as far as practicable
- all receiving fuel oil tanks need to be gauged and the results recorded before taking
delivery of fuel
- do not sign any documentation until you have witnessed the event referred to in the document
- if the origin and method by which the supplier's sample was obtained is unknown then
when signing for it, add the words "for receipt only- source unknown."
- fuel oil samples should be taken by continuous-drip method throughout the bunkering
- if the fuel oil delivered is supplied by more than one barge, a sample should be taken of
each fuel oil from the supplying barges
- sign the bunker delivery receipt only for volume delivered. If the supplier insists on a
signature for weight add "for volume only- weight to be determined after density testing
of representative sample"
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The Chief Engineer and Chief Officer shall jointly be responsible for the inspection and maintenance of the following cargo oil transfer equipment and machinery before entering port. The Chief Engineer shall prepare and maintain the equipment manuals of machinery and equipment, including critical components related to cargo operations including the procedures for their Emergency operation. All items should be in good operational condition.
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