Designation CIMAC A 10

CIMAC B 10

CIMAC C 10

CIMAC D 15

CIMAC E 25

CIMAC F 25

CIMAC G 35

CIMAC H 35

CIMAC K 35

CIMAC H 45

CIMAC K 45

CIMAC H 55

CIMAC K 55

Related to ISO 8217

RMA 10

RMB 10

RMC 10

RMD 15

RME 25

RMF 25

RMG 35

RMH 35

RMK 35

RMH 45

RMK 45

RMH 55 -

Characteristic Dim LimitDensity @ 150C Kg/m3 max. 950 980 1010 991 1010 991 1010

max. 15

min. 6 15Flash point 0C min. 60Pour point 0C max. 24 30Carbon residue %(m/m) max. 14 14 15 20 18Ash %(m/m) max. 0.10 0.10 0.15Total sediment %(m/m) max. 0.10Water %(v/v) max. 0.80Sulphur %(m/m) max. 4.0Vanadium mg/kg max. 300 350 200 500 300Al + Si mg/kg max. 80

Kinematic Visc. @ 1000C cSt

975 991 99110 25 35 45 55

606 30 30 30 30

60 60 60 60

12 22 22 220.15

0.10 0.10 0.10 0.10 0.100.10 0.15 0.15

1.03.5 5.0 5.0 5.0 5.00.50 1.0 1.0 1.0

150 600 600 6008080 808080

• ISO 8217 Specification of Marine Fuels, is the standard tool for the parties involved, i.e. ship owners, fuel suppliers, engine builders, classification societies. The ISO 8217 has been worked out to reflect developments both with regard to the engines and to the product available in the market.

• Fuel within ISO 8217 specifications can also have operational problems and in most of the cases it has been traced to inadequate maintenance of fuel oil treatment plant on board or to a lesser extent on the cylinder oil dosage.

• It is important to emphasise that in a diesel engine there may be differences in working principle, thermal loading, use of materials and in remedies used during many years of service experience. The engine component sensitivity to HFO thus depends on the individual engine and HFO used in the particular situation. Similarly to the HFO, the lube oil can be the cause of the poor performance, rather than the engine components / material choice, operating philosophy or the HFO used.

• Diesel engine fuels include a variety of fuels ranging from gas oils to heavy fuel oils. Gas oil is produced from crude oil by distillation and processing whereas the fuel oil is mainly the residue left after the distillation of crude oil. To obtain the desired viscosity the residue is blended with lighter, less viscous components. Modern refineries use secondary conversion processes such as the visbreaking and catalytic cracking to obtain a higher proportion of lighter products. These products are used as blending stocks for heavy fuel oil.

• Marine fuel oil is purchased by viscosity. All the major companies today, have converted their international marine fuel specifications to the SI system indicating viscosity at 50ºC in the unit mm²/s (= centistokes). However viscosity is still indicated in sec. Redwood No: 1 with 100ºF as reference temperature.

• Effective cleaning can only be ensured by using a centrifuge. To obtain optimum cleaning, it is of utmost importance that the centrifuge operates with as low viscosity as possible and that the fuel oil remains in the centrifuge bowl for as long as possible. The temperature should preferably be approx. 98C. The correct adjustment of the gravity disc is of importance for efficient removal of water from HFO.

• Viscosity:- Fuel grades are based on viscosity. High viscosity fuels are generally cheaper than lower viscosity fuels. Viscosity testing determines the preheating temp. required. It is no problem to reach and operate on 700cSt (50C) viscosity with the standard fuel oil treatment system.

• Density:- Fuel is sold by weight therefore density must be known to determine volume of fuel received. Density must also be determined for selecting the correct size gravity disc for the centrifuges. The ignition and combustion characteristics of higher density fuels may be inferior. Low viscosity, together with high density, may indicate a risk of poor ignition quality. A density higher than 991 kg/m3 calls for automatically adjustable centrifuges.

• Flashpoint:- The flashpoint limit has been set as a safe guard against fire/handling. The limit is set at >60C.

• Sulphur:- The corrosion effect of sulphuric acid during combustion is counteracted by adequate cylinder oils and temperature control of the combustion process. The sulphur content has a negligible effect on the combustion process, but a measurable effect on the cylinder liner and piston ring wear. Furthermore it has a considerable influence on the level of exhaust particulates. (SOx)

• Carbon Conradson Residue (CCR):- This parameter defines the fraction of the non-burnable or difficult to burn part of fuel.

 

• Carbon Residue:- The carbon residue is measured as Conradson Carbon or as Microcarbon. Fuels with increased carbon residue will necessitate more frequent cleaning of turbocharger and exhaust gas boiler. Part of the carbon residue represents asphaltenes.

• Asphaltenes:- The effect of asphaltenes on combustion is similar to carbon residue. Asphaltenes may also affect the fuel oil lubrication properties. In extreme cases, high asphalt content may lead to fuel pump sticking. Fuels with high content of asphaltenes tend to emulsify easily with water.

• Water:- Fuel with a high water content will burn less efficiently. Unless added with a suitable emulsification system in order to reduce Nox – emissions, water in the fuel should be removed by centrifuging the fuel before use. This applies especially to salt water, the sodium content of which may result in deposits on valves and turbochargers. If water cannot be removed, homogenising after centrifuging is recommended. Presence of water will reduce the calorific value of the fuel.

• Ash:- Ash represents solid contaminants as well as metals like vanadium present in the fuel in soluble form. Some of the ash may be catalyst particles from the refining process. Such particles are highly abrasive. Solid ash should be removed to the widest extent by centrifuging.

• Vanadium & Sodium:- Vanadium is, as mentioned, present in the fuel in soluble compounds and, consequently, cannot be removed. In combination with sodium, vanadium may lead to exhaust valve corrosion and turbocharger deposits, especially if the weight ratio of sodium and vanadium exceeds 1:3, and especially if there is a high vanadium content. With smaller contents of sodium and vanadium, the weight ratio is considered less important (for Vanadium content less than 150 mg/kg).

• Sodium normally is present in the fuel as salt water contamination and may, as such, be removed by centrifuging. Sodium may also reach the engine as as airborne sea water mist.

• Aluminium & Silicon:- The limits on aluminium and silicone have been introduced in order to restrict the content of catalytic fines, mainly Al2O3 and SiO2, in the oil. 80mg of Al and Si correspond to up to 170 mg Al2O3 and SiO2.

• Catalytic fines (Aluminosilicates) give rise to abrasive wear in the fuel injection system as well as on cylinder liner/piston rings, and their content should, therefore, be reduced as far as possible by centrifuging the fuel oil before use in the engine.

• Waste lube oil:- Presence of various metals, such as Lead (Pb), Zinc (Zn), Iron (Fe), Calcium (Ca) etc proves that used automobile lube oils are present in the fuel. Iron may also indicate corroded tanks/pipelines.

The fuel oil can be used if the total content of the metal does not exceed the valid content of ash for the fuel oil specification. These metals are present as soluble compounds and are not removed by centrifuging. In exceptional cases, there is a risk of centrifuge blocking if lube oil is present in fuel oil.

• Ignition Quality• The analytic data normally available for fuel oil give no

direct indication of the ignition quality, nor do current specifications and standards. The ignition quality to some extent is predicted by calculations based on viscosity and density, using formulas issued by the oil industry (CCAI by Shell) and (CII by BP).

• CCAI can be calculated by the following formula• CCAI= D – 141 log log ( V + 0.85 ) – 81• Where V= viscosity mm²/s (cSt) @ 50ºC• D= density kg/m³ @ 15ºC• (As a thumb rule, fuels with CCAI less than 840 are

considered good fuels)

High density in combination with low viscosity may be an indication of poor ignition quality on some engines, usually low speed engines are not sensitive to the ignition quality thanks to low rpm, leading to long time available for the ignition process.

Low speed (2-stroke) 60/105 = 0.57 sec/rev. Medium speed (4-stroke) 60/600 = 0.1 sec/rev.  Fuel injection period (~ 22 degrees crankshaft) ~ 35 msec for 2-stroke.

~ 9 msec for 4-stroke.

• To investigate the ignition quality of fuel a “Fuel Ignition Analyser” is developed by Marintek in Norway. The measured ignition delay represents the behaviour of fuel better than the CCAI value. 

• Marintek labels fuels with an ignition delay of 12 msec as “unfit fuels for use” and between 10 and 12 msec as “bad fuels”.

• The ignition delay is not the only parameter of importance for the combustion process. The combustion duration may be even more important in terms of piston ring versus liner operation. The problems caused by the ignition delay can be viewed in terms of rate of pressure rise. A prolonged combustion period causes increased heat loads and eventually increased soot deposits in the ring/liner area.

Combustibility of Asphaltenes

Asphaltenes are hydro-carbons with very high molecular weight, which may not be fully soluble in certain fuel types. This implies the risk of incompatibility of one fuel versus another. In the event of incompatibility the asphaltenes with precipitate and, as a consequence, lead to filter clogging and overloading of centrifuge.

Temperature and time are the factors that will determine the build-up of asphaltenes. The solubility is inversely proportional to temperature and would affect the high temperature side on the system. In a few cases vessels have experienced blocking of filters before engine due to asphaltenes. To avoid this a fine filter (40-50 microns) can be moved to the low temperature system. In order to keep a filter as a last component before the engine, an additional filter of 200-300 microns can be introduced in the high temperature section.

Fuel oil and soot deposits – boilers

• Increasing the thermal efficiency of the diesel engine has led to lower exhaust gas temperatures. The exhaust gas temperature, after the turbocharger, on two stroke engine is between 230 and 270C or even less.

• The steam consumption has remained the same and with lower exhaust gas temperatures, boiler designs have become more and more efficient. Furthermore with more efficient refining process the high quantities of asphalt, carbon and sulphur that contaminate the exhaust gas increases the risk of soot deposits on the exhaust gas boiler tubes, resulting in soot fires.

• Fuel containing special iron oxides additives as a carbon oxidizing agent reduces the stickiness of soot. Such additives are especially useful in cases where exhaust gas boilers are vulnerable to soot deposits.

Residual fuel blending componentsCutter Stock Characteristics

Gas Oils Typically 3 cSt at 50 C and 0.85 density. Predominantly parraffinic in nature. Improves ignition but are expensive and may be incompatible with high asphaltenic residues resulting in instability.

Light Cycle Oils

Typically 3 cSt and 0.97 density. Highly aromatic and gives good stability. Cheaper than gas oils but detrimental to ignition.

Heavy Cycle Oils

Typically 50 cSt and >1.01 density. Highly aromatic, gives very good stability and very cheap. Adverse effect on ignition and carry the risk of extended combustion.

High Density Fuels:

• To cope up with trend towards fuels with density exceeding 999 kg/m³ at 15ºC the centrifuging technology has been further developed with improved clarifiers, with automatic de-sludging properties providing adequate separation of water and particles from the fuel, up to a density of 1010 kg/m³ at 15ºC.

Homogenisers:

• As a supplement only to the centrifuges, a homogeniser may be installed in the fuel system, to homogenize possible water and sludge still present in the fuel after centrifuging.

Fine Filter:

• As a supplement only to the centrifuges, a fine filter with very fine mesh may be installed, to remove possible contaminants present in the fuel after centrifuging.

• A homogeniser should be inserted before the fine filter in order to minimize the risk of blocking by agglomeration of asphaltenes.

Super Decanters:

• As a supplement only, a super decanter may be installed. In principle this is a horizontal clarifier. The aim is to remove sludge before normal centrifuging and thus minimize the risk of blocking of the centrifuges.

Fuel Oil Stability:

• Fuel oils of today are produced on the basis of widely varying crude oils and refinery processes. Certain fuel types may occasionally tend to be unstable when mixed.

• As a consequence, fuel mixing should be avoided to the widest possible extent.

Choosing between 180 cSt and 360 cSt. Fuels.

Grade 180:-

• 7 – 15 % distillate content.

Grade 380:-

• 2 – 5% distillate content.

• Price of Grade 180 is at least US $ 3 - $ 5 more than Grade 380.

 

• Perception is that 180 is better than 380.

• Sulphur: 180 grade samples had 0.7% more sulphur than 380 grade.

• Si+Al: Samples of grade 180 had a total of Al+Si in the range of 22-45 ppm in 0.5% samples than in samples of grade 380.

• Na+Va: 1.5% more samples of grade 180 were nearer to the undesirable 1:3 ration of sodium and vanadium.

 

• Based on reports it is clear that 380 grade is more engine friendly than grade 180.

Designation CIMAC A 10

CIMAC B 10

CIMAC C 10

CIMAC D 15

CIMAC E 25

CIMAC F 25

CIMAC G 35

CIMAC H 35

CIMAC K 35

CIMAC H 45

CIMAC K 45

CIMAC H 55

CIMAC K 55

Related to ISO 8217

RMA 10

RMB 10

RMC 10

RMD 15

RME 25

RMF 25

RMG 35

RMH 35

RMK 35

RMH 45

RMK 45

RMH 55 -

Characteristic Dim LimitDensity @ 150C Kg/m3 max. 950 980 1010 991 1010 991 1010

max. 15

min. 6 15Flash point 0C min. 60Pour point 0C max. 24 30Carbon residue %(m/m) max. 14 14 15 20 18Ash %(m/m) max. 0.10 0.10 0.15Total sediment %(m/m) max. 0.10Water %(v/v) max. 0.80Sulphur %(m/m) max. 4.0Vanadium mg/kg max. 300 350 200 500 300Al + Si mg/kg max. 80

Kinematic Visc. @ 1000C cSt

975 991 99110 25 35 45 55

606 30 30 30 30

60 60 60 60

12 22 22 220.15

0.10 0.10 0.10 0.10 0.100.10 0.15 0.15

1.03.5 5.0 5.0 5.0 5.00.50 1.0 1.0 1.0

150 600 600 6008080 808080

Equal to ISO 8217/CIMAC – H55*1010 provided modern automatic clarifiers are installed

Main Impact Experienced Change in HFO Components in last 10 years.

Density @15C Kg/m³ 991*Kinematic viscosity @ 100ºC cSt 55 @ 50ºC cSt 700Flash Point ºC >60Pour Point ºC 30Carbon residue %(m/m) 22Ash %(m/m) 0.15Total Sediment %(m/m) 0.10Water %(v/v) 1.0Sulphur %(m/m) 5.0Vanadium mg/kg 600Aluminium + Silicon mg/kg 80Asphaltenes**CCAI**Waste lube oil added**

CentrifugingPreheating  HandlingStorage Fouling of gaswaysAbrasive wearCentrifugingInjection equipment & foulingCorrosive wearDeposits and corrosionAbrasive catalytic finesHandling / FilterationIgnition QualityHandling / Filteration

IncreaseIncrease  Small increaseSmall increaseIn average no changeIncreaseSmall increaseSmall increaseIncreaseIncreaseIncreaseIncreaseDecreasedIncrease

 

** Not included in ISO 8217 / CIMAC – H55

Kinematic Visc. @ 100ºC 6 10 15 25 35 45 55

Kinematic Visc. @ 50ºC 22 40 90 190 380 500 700

Sec Redwood 1 @ 100ºF 165 300 600 1500 3500 5000 7000

PROBLEM LIMIT SUGGESTION REMARKS

High Density Limit 991 Extend to 996 if water < 0.5%

Operate as clarifier, heat and settle and drain.

High Viscosity 180 @ 50ºC380 @ 50ºC

225 @ 50ºC 475 @ 50ºC

Tank heating & Fuel heating should be effective.

High Water 1% 3% Related to density and whether it is salt or fresh water.

Carbon Residue 15% 18% Inspect exhaust passages.

Ash 0.1% 0.13% Purify continuously. V, Zn, Mg cannot be reduced. Al, Fe, Si can be. Salt water in fuel increases ash.

Al + Si 80 ppm 100 ppm Further purification can reduce it.

Vanadium 300 ppm 360 ppm Watch for Na:Va ratio 1:3

Total Sediment 0.1% 0.2%  

Sulphur 5% - Limit rarely crossed

CCAI 850 870 Usually a problem with high density low viscosity fuels.

ITEM OIL MAJOR BUNKER BROKER

Price Us $4-5more than broker Competitive price

Supply services Better (where available) Varies, but available everywhere.

Testing Tested in their own labs Tested in Labs of convenience.

Warranties on quality of fuel More customer – friendly Somewhat stringent

Disputes Less likely More likely

Dispute resolution Can be protracted Compromise more likely

Fuel quality Knows exactly what he is supplying

Broker himself may not know and this may result in undesirable fuel

Below is a table of True Worth Index (TWI) of the fuels available at different bunker ports. Worst fuel TWI = 38Best Fuel TWI = 61

REGION TWI

   

Middle East 61

ARA 52

Singapore 51

U.S. Gulf 45

Durban 45

U.S. Northwest 42

U.S. Southeast 38

Fuel Oil Additives: Vessels are using CP 3500, Mergi & Green Plus. Problems associated with incomplete burning of fuel:-         Fuel efficiency is poor-         Power output is lowered-         Hydrocarbons emitted into the environment-         Other emissions pollute the environment-         Carbon build up increasing the engine wear Promises: -         Reduce emissions-         Increase fuel economy-         Reduce oil consumption-         Decrease wear and tear on engine-         Burn away carbon-         Increase life span of combustion system-         Eliminate hot spots caused by uneven combustion of fuel-         Develop more power.

• Assistance to be provided by Fuel Testing Labs during Arbitration and Litigation associated with Bunker Fuel Claims:

 

• 1)     Should be ISO certified.

• 2)     Marine underwriters, insurance companies and P&I clubs should be aware of the lab and they should accept the lab results produced by this lab.

Fuel Purchasing

1)  Confirm that the fuel is as ordered and within ISO8217 limits.

Order by ISO grade. Maximum accepted grades are RMH 55 and K 55.

2)     Analyse fuels. Check if it complies with ISO grade ordered.

 

3)     Inspect the relationship between parameters. Density/Visc., Density/sulphur, Va/Na.

4)   Examine the amount of contaminants and in particular elements that would derive from

used auto oil. Effect on separation.

Turbocharger and uptake deposits. Use of fuel additives.

 5)   Consider elemental analysis of fuel at engine inlet to assess separator efficiency especially

cat fines. (Al+Si) Three monthly assessment.

 6)    Record engine problems against fuel records and supplier. Build database for known commercial use.

Summary • Fuel quality will continue to deteriorate in terms of ignition,

combustion qualities and contaminants. • Fuel must be ordered using the ISO specifications. • Some indication on the quality of fuel and the likely problems

that could be encountered can be derived from analysis report. • MTBO of diesel engine components is only slightly shorter when

HFO is used, compared with the use of diesel oil. • HFO operation can only be optimum if there is a proper and

adequate HFO treatment on board.