technical aspects of identifying and managing bunker problems · pdf filetechnical aspects of...

KALIMBASSIERIS MARITIME






Dimitrios V. Giannakouros, Naval Architect & Marine Engineer

Technical Director, Kalimbassieris Maritime

The Marine Club, Thursday 8 November 2012

Technical Aspects

of Identifying and Managing

Bunker Problems


1. ISO Standards

• ISO 8217:2005

• ISO 8217:2010

• ISO 8217:2012

2. Sampling operation

• Representative sampling

• IMO sampling guidelines

• In-line continuous drip sample

• Labelling / sealing of samples

• Pitfalls in sampling

3. Shore based testing of fuel

• Why

• Selection of laboratory

• Procedure

4. Off-spec bunkers

• True Value – Repeatability – Reproducibility

• When bunkers are considered off-spec

5. Engine problems due to off-spec bunkers

• Density

• Viscosity

• Sulphur

• Aluminium + Silicon

• Water

• Ash

• Vanadium

• Sodium

• CCAI

6. Suggestions / Conclusions


Fractioning Column


Five editions:

• 1987 – first edition

• 1996 – not in use any more

• 2005 - most widely used specification

• 2010 – provides for better fuel quality

• 2012 - adding test method for H2S content

ISO 8217

Petroleum products – Fuels (class F) –

Specifications of marine fuels

Scope:

It specifies the requirements for petroleum fuels for use in marine

diesel engines and boilers, prior to appropriate treatment before

use


• Max. water content 0.5% from 1%

• Max. sulphur content 4.5% from 5.0%

• Restriction of used lubrication oil (ULO) by setting max. limit for

Zn, Ca & P

• Max. ash level 0.15% from 0.2% (for some highly viscous grades)

• However, some characteristics not yet included or other with too

high limits (e.g. Al + Si, 80 ppm)

• 2005 version remains the most widely used specification although

since that time the Standard has been revised twice

ISO 8217:2005 – Major changes for residual fuels


ISO 8217:2010 – Significant improvement of fuel quality

What is new in 2010 edition ?

Distillate Fuels Residual Fuels Purpose

Acid number Minimize damage to diesel engine fuel

injection from high acidic compounds

H2S

(from 1st July 2012)

Provide improved margin of safety by

reducing risk of exposure to shipboard

crew

Lubricity (for samples with S<0.05%)

Avoid fuel pump wear due to too low

lubricity

Oxidation stability Minimize addition of bio-diesel (FAME)

to reduce storage risk on board vessel

CCAI Avoid uncharacteristic density viscosity

relationship leading to ignition problem

Sodium Limit any sea water contamination and

restrict high temperature corrosion

• It specifies 4 categories of distillate fuel, one of which is for diesel

engines for emergency purposes, and 6 categories of residual fuel



What has changed for residual fuels in 2010 edition ?

• RMA 10 grade was added (previous DMC grade)

• RMG and RMK grades were expanded to include additional

viscosity grades

• RMF and RMH grades were removed

• Sulphur limits were excluded from residual fuel limits, as these

are controlled by statutory requirements

• Sulphur limits for distillate fuels were retained

• Ash limit values, for residual fuels, were reduced for many of

the categories (RMG 380 from 0.15% m/m to 0.10% m/m)

• Vanadium limit for RMG 380 was increased from 300 ppm to

350 ppm

• Vanadium limits for other grades were reduced, but for RMB 30

where limit remained unchanged

• Catfine (Al + Si) limits were reduced from 80 ppm to 60 ppm


Parameter Unit Limit DMX DMA DMZ DMB

Viscosity at 40°C mm²/s Max 5.500 6.000 6.000 11.00

Viscosity at 40°C mm²/s Min 1.400 2.000 3.000 2.000

Micro Carbon Residue

at 10% Residue % m/m Max 0.30 0.30 0.30 -

Density at 15°C kg/m3 Max - 890.0 890.0 900.0

Micro Carbon Residue % m/m Max - - - 0.30

Sulphur a % m/m Max 1.00 1.50 1.50 2.00

Water % V/V Max - - - 0.30 b

Total sediment by hot filtration % m/m Max - - - 0.10 b

Ash % m/m Max 0.010 0.010 0.010 0.010

Flash point 0°C Min 43.0 60.0 60.0 60.0

Pour point, Summer 0°C Max - 0 0 6

Pour point, Winter °C Max - -6 -6 0

Cloud point °C Max -16 - - -

Calculated Cetane Index Min 45 40 40 35

Acid Number mgKOH/g Max 0.5 0.5 0.5 0.5

Oxidation stability g/m3 Max 25 25 25 25 c

Lubricity, corrected wear scar

diameter (wsd 1.4) at 60°C d um Max 520 520 520 520 c

Hydrogen sulphide e mg/kg Max 2.00 2.00 2.00 2.00

Appearance Clear & Bright f b, c

ISO 8217:2010 - MARINE DISTILLATE FUELS


a

A sulphur limit of 1.00% m/m applies in the Emission Control Areas designated by the International Maritime Organization. As there may be local variations, the purchaser shall define the maximum sulphur content according to the relevant statutory requirements, notwithstanding the limits given in this table.

b If the sample is not clear and bright, total sediment by hot filtration and water test shall be required.

c Oxidation stability and lubricity tests are not applicable if the sample is not clear and bright.

d Applicable if sulphur is less than 0.050% m/m.

e Effective only from 1 July 2012.

f If the sample is dyed and not transparent, water test shall be required. The water content shall not exceed 200 mg/kg (0.02% m/m).

ISO 8217:2010 - MARINE DISTILLATE FUELS

Explanatory notes


Parameter Unit Limit RMA a RMB RMD RME RMG RMK

10 30 80 180 180 380 500 700 380 500 700

Viscosity at 50°C mm²/s Max 10.00 30.00 80.00 180.0 180.0 380.0 500.0 700.0 380.0 500.0 700.0

Density at 15°C kg/m3 Max 920.0 960.0 975.0 991.0 991.0 1010.0

Micro Carbon Residue % m/m Max 2.50 10.00 14.00 15.00 18.00 20.00

Aluminium + Silicon mg/kg Max 25 40 50 60

Sodium mg/kg Max 50 100 50 100

Ash % m/m Max 0.040 0.070 0.100 0.150

Vanadium mg/kg Max 50 150 350 450

CCAI - Max 850 860 870

Water % V/V Max 0.30 0.50

Pour point (upper) b,

Summer

°C Max 6 30

Pour point (upper) b,

Winter

°C Max 0 30

Flash point °C Min 60.0

Sulphur c % m/m Max Statutory requirements

Total Sediment, aged % m/m Max 0.10

Acid Number e mgKOH/g Max 2.5

Used lubricating oils

(ULO):

Calcium and Zinc; or

Calcium and

Phosphorus

mg/kg - The fuel shall be free from ULO, and shall be considered to contain ULO when either one of the following conditions is

met:

Calcium > 30 and zinc >15; or

Calcium > 30 and phosphorus > 15.

Hydrogen sulphide d mg/kg Max 2.00

ISO 8217:2010 - MARINE RESIDUAL FUELS


a This residual marine fuel grade is formerly DMC distillate under ISO 8217:2005.

b Purchasers shall ensure that this pour point is suitable for the equipment on board, especially in cold climates.

c The purchaser shall define the maximum sulphur content according to the relevant statutory requirements.

d Effective only from 1 July 2012.

e

Strong acids are not acceptable, even at levels not detectable by the standard test methods for SAN. As acid numbers below the values stated in the table do not guarantee that the fuels are free from problems associated with the presence of acidic compounds, it is the responsibility of the supplier and the purchaser to agree upon an acceptable acid number.

ISO 8217:2010 - MARINE RESIDUAL FUELS

Explanatory notes


Implementation of ISO 8217:2005 vs ISO 8217:2010

Source DNVPS


Why to change to ISO 8217:2010 when ordering fuel?

• Provides for better fuel quality

• Improvement of the safety levels in shipboard operation

• Reduced engine damage and consequential risks

• Positively affects Owners’ image and reputation


Therefore, when moving from ISO 8217:2005 ....

...go straight to ISO 8217:2012

• Became available on 15th August 2012, in response to concerns

for measuring H2S content

• Introduced test method, IP 570, Procedure A (with Vapour Phase

Processor) as the reference test method

ISO 8217:2012


• Maybe the most important aspect during bunkering

• Provides evidence for possible quality disputes

• Should be carried out with methodical manner and utmost care

• Main objective: to obtain “representative” sample from the bunkered

fuel

• Very difficult in case of in-line blending

What is representative sample?

a product specimen having its physical

and chemical characteristics identical

to the average characteristics of the

total volume being sampled

IMO Resolution MEPC.182(59)

SAMPLING OPERATION


IMO Resolution MEPC.182(59)

2009 Guidelines for the sampling of fuel oil for

determination of compliance with the revised MARPOL

Annex VI

• Came in response to Annex VI to MARPOL 73/78

(regulation 18.8.1: BDN shall be accompanied by

a representative sample of the fuel oil delivered)

• Is based on the ISO Technical report No. ISO/TR 13739

• Provides guidelines for sampling method & location, sample

taking, integrity, handling, sealing and storage

• Refers to MARPOL sample, only

• May form the basis for commercial sampling procedures, as

well


The sample should be:

• Collected throughout the bunkering period

• Obtained by the sampling equipment positioned at the bunker

manifold of the receiving ship

• Obtained by manual valve-setting continuous-drip sampler; or

time / flow proportional automatic sampler

• Of sufficient quantity not less than 400 ml (bottle filled to 90% ±

5% capacity), properly sealed and labelled

• Kept in a safe storage location, not subject to elevated

temperatures, preferably at a cool/ambient temperature, and not

exposed to direct sunlight

• Retained under the ship’s control until the fuel oil is substantially

consumed, but in any case for a period of not less than 12 months

from the time of delivery


In-line continuous drip sampling

• Manual or automatic

• Manual sampler developed by DNVPS

• Consists of sample probe with holes, screwed into stainless steel

flange, through which sample is collected in cubitainer

• Manual continuous drip sampling is as good as the automatic

one, provided recommended procedure will be followed with

care

Photos by

DNVPS


Manual continuous drip sampler (DNVPS)


• The sampler is connected

directly to the bunker manifold

by pipe fittings

• After start, it will fill one 5 litre

cubitainer and stop automatically

after the preset bunker time in

hours has expired

Automatic continuous bunker sampler


Remember to:

1. Stir & Shake the cubitainer

before distributing the sample

2. Reduce viscosity of sample, if

cold weather, for assisting

mixing

3. Distribute evenly the

sample into individual

bottles, by filling

each bottle a little at

a time

4. Ensure that the

contents of each

bottle are similar

Photos by DNVPS


How many sample bottles to prepare?

• One (1) To laboratory for testing

• One (1) To be kept onboard as reference

• One (1) To bunker suppliers

• One (1) MARPOL sample to be kept onboard for 12 months

(cannot be used for commercial analysis)

Totally 4 sample bottles (at least)

Photos by

DNVPS


Maritime and Port Authority of

Singapore Code of Practice

for Bunkering (CP 60)

1. One sample for the vessel

2. One MARPOL sample for the

vessel’s retention

3. One sample for the bunker tanker

4. One sample for the bunker

surveyor, if engaged (if not,this

fourth sample shall be retained by

the bunker tanker)

5. One sample for the vessel, if the

vessel is on a fuel quality testing

programme (if not,this sample

needs not be collected)

• 5 samples to be collected:


Sealing & Labelling

• Follow the IMO Guidelines - Resolution MEPC.182(59)

• Installation of security seal with identification no. by the

supplier’s representative in the presence of the ship’s staff

• The label of sample bottles should indicate:

1. location at which, and the method by which, the sample was

drawn;

2. date / place of commencement of delivery;

3. name of bunker tanker/bunker installation;

4. name and IMO number of the receiving ship;

5. signatures and names of the supplier’s representative and the

ship’s representative;

6. details of seal identification; and

7. bunker grade

• Seal number to be also recorded on the BDN


Sampling can go wrong in case of:

• Taking spot samples from drain cocks

• Using a dirty continuous drip sampler

• Using unclean and wet cubitainer and sample bottles

• Pouring the cubitainer content into sample bottles without

shaking

• Unevenly distributing the bulk sample into the bottles

• Accepting uncontrolled samples given by the bunker suppliers

And always have in mind:

Testing results are as good as the

sample given for analysis


SHORE BASED TESTING OF BUNKERED FUEL

Is it necessary and why?

1. Assess conformation with

specification or other quality

requirements

2. Decide on the acceptance of the

product prior to its use

Do not ignore that lack of testing or the improper use of off-spec

bunkers can lead to extensive damage to vessel’s machinery,

which is costly both to Owner and the insurer

3. Take the required measures onboard for fuel oil treatment,

aiming at minimizing the problems during or after consumption


Criteria for laboratory selection

• Being independent

• Having experience with the testing of fuel oils

• Using the appropriate test methods as listed in the ISO 8217

Standard

• Being certified as per ISO or accredited as per National

accreditation scheme

• Providing results promptly

• Providing commercial & technical advice regarding the

results

• Being recognized by all parties in case of quality dispute

• The biggest not always the best

In case of doubt, seek advice from technical consultant


Which is the procedure?

• Agreeing with the other parties on:

• Ensuring that the correct sample(s) is (are) brought to the lab

• Ensuring that all parties are in attendance

• Checking whether the seal of the bottle(s) is (are) intact

• Taking photos of the bottle/seal before breaking the seal

• Unsealing the bottle in the presence of parties in attendance

• Re-sealing the bottle with new seals, in case analysis is to be

repeated (at same or another lab)

• Signing a relevant unsealing/re-sealing protocol that is normally

prepared on the spot by the lab

– samples to be analysed

– nature and extent of analysis

– standards to be used

– laboratory to be used


True value

• The limits specified in the ISO 8217 standard refer to the “true

value” of a given property as measured by the specified method

• True value is the average of an infinite number of single results

obtained by an infinite number of laboratories (ISO 4259:2006)

• The true value can never be obtained

Repeatability, r

The variation of results, when a fuel test is run a number of times

at the same laboratory, by the same person, on the same sample,

under the same conditions

Reproducibility, R

The variation of results, when two different laboratories test the

same sample using the same method

When bunkers are off spec ?


After a single test result:

For the receiver, the fuel fails the specification limit,

with 95% confidence, only if:

• Test result > limit + 0.59 x R (for max. limits) or

• Test result < limit - 0.59 x R (for min. limits)

For the supplier, the fuel meets the specification limit,

with 95% confidence, only if:

• Test result ≤ limit - 0.59 x R (for max. limits) or

• Test result ≥ limit + 0.59 x R (for min. limits)


Two examples:

Kinematic viscosity - RMG 380 grade

Maximum limit = 380 cSt at 50o C

R = 0.074 x 380

Variation (margin) of result = 0.59 x 0.074 x 380 cSt = 16.59 cSt

Therefore, a residual fuel of RMG 380 grade is considered to fail the

viscosity specification, with 95% confidence, if the single test result

is greater than 396.59 cSt at 50o C

Cat fines (Al + Si) - RMG 180 grade

Maximum limit = 60 ppm

R = 0.3345 x 60

Variation (margin) of result = 0.59 x 0.3345 x 60 ppm = 11.84 ppm

Therefore, a residual fuel of RMG 180 grade is considered to fail the

cat fines specification, with 95% confidence, if the single test result

is greater than 71.84 ppm


Quality Parameter ISO Limit Reproducibility ‘R’ 0.59R Result ‘out of spec’

if above this value

(limit + 0.59R)

Viscosity at 50o C (max) 180 0.074x180=13.32 7.86 187.86

380 0.074x380=28.12 16.59 396.59

Density at 15o C (max) 991 1.5 0.885 991.885

Al+Si (ICP method) 60

0.3345x60=20.07 11.84 71.84

Flash Point (min) 60o C 6 3.54 56.46

Ash 0.1% 0.024 0.014 0.114

Total Sediment 0.1% 0.294x√0.1=0.055 0.032 0.132

Interpretation of a single test result

ISO 4259:2006

Petroleum products - Determination and application of precision

data in relation to methods of test


• Contracts signed between fuel sellers and buyers, refer to ISO

4259

• In practice, test results are not interpreted according to ISO 4259

provisions

• It is common for the bunker receivers to raise a claim even when

the single test results are outside the limits prescribed by the ISO

8217 standard, i.e. without taking into account the R margins

• ISO 4529 provides a specific procedure if the receiver and the

supplier have tested the same sample in different laboratories and

find that they cannot agree on the value to be accepted

• Most bunker disputes between receivers and suppliers are solved

on commercial basis

• Owners to have in mind that if a dispute is referred to arbitration,

the suppliers are normally entitled to make use of the ISO 4259

Standard provisions



SPECIFIED PARAMETERS FOR IFO 180 - RME 180 & TEST RESULTS

Parameters Units Test Results Specification Limits

------------------------------------------------------------------------------------------------------------

Density @ 15°C kg/m3 984.7 (991.0 Max)

Viscocity @50°C cSt 187.1 (180.0 Max)

Upper Pour Point °C 3 (30 Max)

Carbon Residue % (mass) 14.92 (15.00 Max)

Ash % (mass) 0.080 (0.100 Max)

Water % (vol) 0.30 (0.50 Max)

Sulphur % (mass) 2.85 (3.50 Max)

Total Sediment Pot. % (mass) 0.02 (0.10 Max)

Vanadium ppm 121 (200 Max)

Al + Si ppm 235 (80 Max)

Flash Point °C > 70 (60 Min)

Calcium ppm 7 (- Max)

Zinc ppm < 1 (- Max)

Phosphorus ppm 1 (- Max)

ADDITIONAL PARAMETERS

---------------------

Parameters Test Results Units

---------------------------------------------------------------------------------

Viscocity @100°C 22.6 cSt

API Gravity 12.12

Sodium 30 ppm

Aluminium 134 ppm

Silicon 101 ppm

Iron 26 ppm

Lead < 1 ppm

Nickel 28 ppm

Magnesium 2 ppm

Potassium 1 ppm

CALCULATED VALUES

-----------------

Parameters Computed Val Units

----------------------------------------------------------------------------------

Net specific energy 40.21 MJ/kg

Gross specific energy 42.51 MJ/kg

CCAI 853

Temperature at injection (for 13 cSt) 120 °C

Minimum Transfer Temperature 32 °C


Density

• Max limits: 991 Kg/m3 (RMG Grade) & 1010 Kg/m3 (RMK Grade)

• It is the relation ship between mass and volume at a defined

temperature (15o C)

• Increased density may:

- Affect the centrifuge operation (ineffective in water removal)

- Affect the engine’s performance (increase of CCAI, with

viscosity constant)

- Reduce the specific energy of the fuel

• Reduced density than that declared by suppliers, results in

economical loss for the buyers; bunkers are sold by weight, but

delivered by volume

Example: Bunkered quantity delivered onboard: 2000 m3

Density, as declared by the suppliers: 991 Kg/m3

Density, as determined by the laboratory: 985 Kg/m3

Short delivery, 2000 m3 x (991–985) Kg/m3=12 tons


Viscosity

• Viscosity is a measure of how fuel will flow and it varies with

temperature; as heavy oil is heated, it will flow more easily

• Viscosity is measured at 40o C for distillate and 50o C for residual

fuels

• For residual oils, the common viscosity is 180 cSt and 380 cSt, but

it reaches up to 700 cSt

• Viscosity greater than specified, may affect pumpability,

preheating, settling / separation, spray formation, atomization and

combustion

• The maximum viscosity of the fuel that can be used in an engine

depends on the heating facilities available

• However, too hot fuel, part of it may turn to gas at the injection

pumps, which is preventing the generation of proper injection

pressure


Fuel Viscosity

cSt

Injection Temperature Fuel Viscosity

cSt

Injection Temperature

For 10 cSt For 15 cSt For 10 cSt For 15 cSt

100 117 101 320 142 125

120 121 105 340 143 126

140 124 108 360 145 127

160 127 111 380 146 128

180 130 113 400 147 129

200 132 116 420 148 130

220 134 118 440 149 131

240 136 119 460 149 132

260 138 121 480 150 133

280 139 122 500 151 134

300 141 124

• Increased viscosity is not a problem for the engine, provided that

it is reduced to levels recommended by the engine manufacturers

(10-15 cSt at engine inlet)


Receipt Data Unit

------------ ----

Source Of Data Ch.Eng

Density @ 15oC kg/m3 968.2

Viscosity @ 50oC mm2/s 160.0

Sulfur % m/m 2.47

Test Parameter Unit Result RME180

-------------- ---- ------ ------

Density @ 15oC kg/m3 987.8 991.0

Viscosity @ 50oC mm2/s 306.7 180.0

Water % V/V 0.3 0.5

Micro Carbon Residue % m/m 14 15

Sulfur % m/m 2.52 4.50

Total Sediment Potential % m/m 0.01 0.10

Ash % m/m 0.08 0.10

Vanadium mg/kg 164 200

Sodium mg/kg 43

Aluminium mg/kg 13

Silicon mg/kg 14

Iron mg/kg 51

Nickel mg/kg 52

Calcium mg/kg 37

Magnesium mg/kg 3

Lead mg/kg LT 1

Zinc mg/kg 4

Phosphorus mg/kg 3

Potassium mg/kg LT 1

Pour Point oC LT 24 30

Flash Point oC GT 70 60

Calculated Values

-----------------

Aluminium + Silicon mg/kg 27 80

Net Specific Energy MJ/kg 40.28

CCAI (Ignition Quality) - 851


Sulphur

• Sulphur content is dependant on the geographical source of crude

oil and the degree of blending with low-sulphur components

• Sulphur will burn to form sulphur oxides (SOx) which may convert

to corrosive acids under certain conditions (low temperatures) and

cause corrosion to low temperature zones (“cold corrosion”)

• Acidity is neutralized by the alkalinity of the cylinder lubricating

oil (BN)

• Selection of cylinder oil depending on the sulphur content of the

fuel oil

• Low-sulphur fuels (below 1%), if used with high BN cylinder

lubricating oil, will result in overdose with alkaline additives,

leading to alkaline deposits on the piston top land


Accumulation of alkaline deposits on piston crown’s topland

• Alkaline deposits will scrape-off cylinder oil film, resulting in dry

friction between the cylinder wall and piston rings and the

development of cylinder liner scuffing

Recommended action:

• Carefully select the cylinder lubricating oil to be compatible

with fuel oil sulphur content

• Carry 2 grades of cylinder oil; one for use with high sulphur

fuel and the other for operation on low sulphur fuel


Aluminium + Silicon

• Limit as per ISO 8217:2010, RMG & RMK grades – 60 ppm (previous

80 ppm)

• Hard and abrasive particles used as catalyst in petroleum refining

process

• Engine manufacturers limit the amount of catalytic fines in the

fuel injected into the engines to 15 mg/kg

• Not always evenly distributed in the fuel. Sometimes accumulated

in the sediment

• Very difficult to be removed, as they are attracted to water

droplets


Exceeding the level of Al+Si of 15 mg/kg at the engine’s inlet ....

... may cause excessive wear of the components in the combustion

chamber (piston grooves, piston rings, cylinder liners) and of the fuel

injection equipment (fuel pump plunger and barrel, fuel injection

valves)

Photos by DNVPS


Precautions to take:

• Maintain the separators according

to manufacturers’ instructions,

using approved spare parts

• Ensure efficient centrifuging

through FO separators, which will

reduce Al+Si content to

acceptable levels (reduced

throughput and temperature

around 98°C)

• Thorough separation required even if bunkered fuel within

specification (catfines settle in the tank and may be supplied

to the FO system during rough weather)


Precautions to take: (continued)

• Consider reducing consumption/speed to ensure reduced flow

through separator

• Check fuel system efficiency by taking samples before and after

separator, to gauge the fuel oil quality, at intervals of 4 to 6

months

• Also take samples before engine inlet, to assess whether

makers’ requirements are met

• Clean storage, settling and service tanks at regular intervals

• Train personnel for the operation and maintenance of

separators

Embedded catfines (red arrows) and

abrasive wear traces


• If accelerated cylinder liner wear (>0.1mm/1000 hrs), take replica

imprints for microscopic examination, to assess whether catfines

are embedded



Micrograph of normal surface

(20x magnification)


(20x magnification)




(20x magnification)


(20x magnification)




(20x magnification)




(20x magnification)




(20x magnification)




(20x magnification)




Water

• Allowed up to 0.5% v/v for residual fuels and 0.3% v/v for distillate

fuels (DMB)

• Water reduces specific energy

• Water may lead to a wide range of engine problems depending on

the source of the water; fresh or seawater

• Fresh water contamination from condensation, leaking steam

heating coils, badly set up centrifuges and rain water ingress

through tank lids or sounding pipes

• It may lead to corrosion damages to fuel pumps and injectors

• Removal of fresh water by centrifuging only if free in the fuel

(emulsification renders the separation difficult, if at all possible)


• Seawater contamination, usually from bunkering barges, is more

serious because of the sodium content (1.0% seawater in the fuel

oil corresponds to 100ppm sodium)

• Ash deposits on exhaust valves and turbochargers

• High-temperature corrosion, as a result of chemical reaction

between the sodium and vanadium in the fuel, when

sodium/vanadium ratio = 1:3

• Recommended centrifuging

separation, sufficient settling time,

sufficient heating in the settling

tanks and by the use of proper

draining arrangements on the

settling and service tanks


Ash

• Allowed up to 0.15% m/m, for residual and 0.01% m/m, for

distillate fuels

• During combustion, metal content is converted into solid ash

particles, which - at certain temperatures - become partly fluid,

adhering and causing corrosion damage to piston crowns, exhaust

valves, turbocharger blade surfaces and boiler tubes

• Stiction temperature is lowest for ashes that are rich in vanadium

and/or sodium

• A sodium/vanadium ratio of 1:3 is generally facilitating the

phenomenon of high temperature corrosion to occur, as ash

melting temperature is even below 400o C

• Ash removal recommended by frequent cleaning


Vanadium

• Allowed up to 450 ppm for RMK and 350 ppm for RMG grades

• Vanadium in fuel oil occurs naturally and content varies depending

on the origin (Mexican & Venezuelan fuels with highest V content)

• Vanadium is not a major problem in itself, but it becomes an issue

when accompanied by high levels of sodium.

• No practical methods for removing vanadium onboard a ship. The

only way is to restrict V in the fuel oil is by lowering allowed limit


Sodium

• Allowed up to 100 ppm for RMK & RMG grades

• Sodium is found originally in fuel oil and very occasionally the

sodium hydroxide used in the refining process

• Fuels normally have a sodium content between about 10 ppm and

50 ppm

• Sodium in contaminating seawater greatly increases the problems,

i.e. high temperature corrosion (1% by mass seawater 100 ppm

of sodium content)

• Unlike vanadium, sodium can be removed by water removal

(centrifugal treatment and settling)

• Also, high temperature corrosion problems are limited by:

- Efficient cooling of valve seats and faces

- Use of valve rotators to even out the thermal load on the valves

- Use of corrosion-resistant materials (stellite and nimonic steels)


Calculated Carbon Aromaticity Index (CCAI)

• Introduced in ISO 8217:2010

standard. Max. limit 870 for

RMG & RMK grades

• CCAI is not determined by a

specific testing method, but

calculated with a specific

formula on the basis of

density and viscosity

• CCAI value can be read from

nomogram (aside)

• CCAI does not provide

information related to the

combustion characteristics,

but an indication of ignition

delay (knocking)


• CCAI between 850 and 860 would

render better fuels. Residual fuels

with a CCAI higher than 870 are

often problematic

• FIA (Fuel Ignition Analysis) is a

reliable means to assess the

ignition quality of fuels based on

an actually measured ignition

delay

• Ignition quality of a fuel is

expressed as FIA CN (Cetane

Number), ranging for heavy fuels

from less than 18.7 to above 40

• The combustion properties of a

fuel are evaluated by means of the

ROHR (Rate of Heat Release)

curve. Fuel Ignition Analyser FIA 100/3


Pressure Curve

Rate of Heat Release (ROHR) Curve


Conclusions / Tips

• Order fuel to desired ISO grade and describe it in the charterparty,

as well as in the requisition to supplier

• Insist in the fuel meeting the specifications set out in

ISO8217:2010

• Take representative samples at the time of delivery. Ensure that

the samples taken are properly labelled

• If the supplier takes other samples at the time of the delivery, try

to establish how and when they were obtained. Protest if not

invited to witness the taking of these samples

• Make use of reliable fuel testing services such as DNV Petroleum

Services (DNVPS) or Lloyds Register (FOBAS)

• Segregate new fuel from that held on board (not always possible

though)

• Avoid using new fuel until the analysis results have been examined

and it has been established that it is suitable


Conclusions / Tips (continued)

• Maintain records of previous bunkering operations, including BDN

and/or sampling reports

• Maintain careful reliable daily records of the contents and

consumption from each fuel tank

• Ensure good maintenance and calibration records are kept for all

machinery

• Ensure engine log books properly record all temperatures,

pressures and remarks of engine performance on a daily basis

• Consider de-bunkering of off-spec bunkers, if unsuitable for use

• If inferior quality bunkers have to be used, the charterers (if

purchased the fuel) and bunker supplier should be informed and

put on notice for possible damages. Insurers are also to be

informed

• Contact the engine manufacturer for advice, depending on which

parameter is off-specification and/or what the particular problem

is (the degree of quality deviation from the specification must be

considered)


Last, but not least, contact an expert /consultant.

Thank you, for your attention !!

He will provide advice on how to proceed and assist you to solve

the particular problem, to avoid damage and mitigate losses

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