Answer: (a) +(b)

(a + b), Consequences & Adjustments to use the fuel

Density: 

• The supplier has claimed the density is 996.5 kg/m3, but the result is 992 kg/m3.

• For the same volume supplied, the mass quantity is less, charterers are to be informed & the actual quantity on board must be adjusted.

Consequences: 

• Check the purifier on board.  
• If it can handle up to 1010 kg/m3, then no problem.  If it is conventional type (can handle up to 991 kg/m3) then interface  may be  shifted  outwards & possibility of oil leaks through water outlet

Adjustment:   

• Check nomogram, accordingly, select a smaller diameter of gravity disc.  
• Maintain purifier operating temperature around 95-98◦C

Viscosity: 

• Viscosity is high 

Consequences 

• Ignition delay & after burning may occur.
• Impingement may occur  

Adjustment:  

• To obtain correct viscosity of 12-15 cst , the fuel injection temperature needs to be increased.

Water:  

• Water content is within limit. If it is high then, 

Consequences:

• Microbial degradation. 
• Affect proper combustion.  
• Water reduces the calorific value & increases SFOC.
• May not be good for cylinder oil film formation.  

Adjustment: 

•  Frequent draining of settling/service tanks
•  by proper purification

Carbon residue: 

• Above limit & found in soluble form.  

Consequences: 

• Deposit on piston ring groove and fouling of T/C inlet grids, nozzle rings & turbines blades.  
• Increase soot formation at EGE.

Adjustment: 

• Increase the frequency of T/C grit washing.  
• Increase the frequency of soot blowing & water washing of EGE.  
• Increase the frequency of scavenge & under piston space cleaning.  
• Inspection for scuffing at every opportunity.

Sulphur:

• Within limit but not for use in ECA area. After 1st January 2015, the ECA limit is 0.1%.
• After 1^st January 2020, the Global limit is 0.5%. 

Adjustment:

Ensure the TBN of the cylinder oil is suitable for low sulphur oil.

Ash

• Above limit & mostly found in insoluble form.  

Consequences:  

• Ash causes abrasive wear in liner and fuel pump.
• Scuffing & injector atomizing holes enlargement. 
• Deposit on piston ring grooves, fouling of T/C inlet grids, Nozzle rings & turbine blades increased
• Increase soot formation at EGE.  

Adjustment:  

• Operate the centrifuges in series as purifier & then clarifier.  
• Operate the centrifuges at optimum throughput. (5-10% above the consumption) 
• Reduce the interval of de-sludging. 
• Reduce the flushing interval of back flushing filters. 
• Increase the frequency of all fuel filters cleaning

Vanadium:

Within limit. Found in natural form.

If it is high then,

Consequences :

• Known for its high temperature corrosion 
• Combines with sodium to form a molten paste at temp around 500◦C. 
• Leave sticky deposits on the exhaust v/v, piston crown, cylinder head, T/C.

Adjustment:  

• Maintain exhaust temperature below 500◦C

Flashpoint: 

→ Within limit 

Adjustment: 

• Fuel oil temperature should not exceed 160◦C ( 170°C-10°C=160°C)
• Flashpoint should be minimum 60°C as per SOLAS. Reject if flashpoint value is lower than standard value

Pour Point:

Within limit. 

Adjustment:

• Maintain bunker tanks temp above 30°C(20+10)

Aluminium + Silicon:

Within limit. If it is high,

Consequences: 

• Abnormal wear of fuel p/p plunger & barrels.
• Scuffing & injector atomizing holes enlargement. 
•  Associated with abrasive wear (as hard as diamond) 
• Increase liner and piston ring wear
• Piston ring grooves deposits and fouling of T/C inlet grids, Nozzle rings, & turbine blades increased.  

Adjustment:

• Operate the centrifuges in series as purifier & then clarifier.  
• Operate the centrifuges at optimum through put. (5-10% above the consumption) 
• Reduce the interval of de-sludging. 
• Reduce the interval of back flushing filters. 
• Increase the frequency of all fuel filters cleaning 

Total sediment (aged):

Within limit, This related to ageing and blending of oil If it is high, 

Adjustment: 

• Consume this bunker first. 
• Operate purifiers and de-sludge regularly. 
• Try to keep in circulation as often as possible 

Zinc, Phosphorous, Calcium: (ULO)  

Above limit. Presence of used lube oil (ULO- Used Lube Oil) 

Consequences:

The formation of deposits will increase

CCAI (Calculated Carbon Aromaticity Index):

Within acceptable range. CCAI [1]determines the ignition quality of residual fuel oil although scientifically not proven. If high

Consequence:

• Higher CCAI determines lower ignition quality of fuel
• CCAI value determined from density and viscosity of fuel
• CCAI value more than 870 is unacceptable, indicates low ignition quality of fuel, leads to ignition delay
• After burning
• Low peak pressure
• High exhaust temp
• Lower power output

Adjustment:

Advance VIT

Acid number: 

Above limit and presence of inorganic acids.

 Adjustments: 

• Slightly increase the cylinder lubrication to neutralize the presence of acids.   

Hydrogen sulfide: 

Within limit. If it is high, 

Consequences 

• Tests to be carried out for human safety in the vicinity of the fuel tanks and vent
• Also contributes to acidity 
• It is a colorless gas having foul odor of rotten eggs; it is heavier than air very poisonous, corrosive, flammable, and explosive.

Sodium: 

Above limit.

Consequences:

• Suspect seawater contamination  

• Risk of high-temperature corrosion

Adjustment:  

• Frequent draining of settling and service tank
• Increase T/c grit washing frequently
• Maintain exhaust temp bellow 500◦C 

c)  Not satisfying IMO regulation

• This fuel oil clearly indicates the presence of used lube oil [2] & inorganic acid
• As per MARPOL Annex VI regulation 18, the presence of ULO (Used Lube Oil) & inorganic acids is UNACCEPTABLE.  
• A letter of protest must be issued to the charterers.  

[1] CCAI is the ratio of the fuel which indicates ignition quality because ignition directly depends on the Aromatic Content in the fuel

[2] Ca>30, Zn>15, Ph>15 mg/kg, any two Ca and Zinc or Ca and Ph