(By Kamal Hossain, Chief Engineer)
Pollution prevention
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- Pre-bunkering meeting should be held , quantity , grade and distribution plan to be drawn up.
- By considering of volume allowance is 10 ~ 15 % for expansion , all tanks to be filled up to 85 % maximum.
- Clear over flow tank , drain tank .
- Top up settling and service tanks.
- Clean filters and sight glass of bunker line.
- Keep level indicator, sounding gauge and pressure gauge good working order.
- Arrange quick communication between bunker point and control .
- Check scuppers plug condition.
- Keep cleaning materials and chemical near by bunker point.
- Alert oil pollution control team as per contingency plan.
- Exact reading of draught and list to calculate trim of the ship. Keep vessel up right as possible.
- All tanks to be sounded priorly.
- Check valve opening to correct tank and others shut.
- Predetermine the pumping rate and emergency stop signal with supply barge.
- Pumping slowly during first stage , check oil enter to correct tank , hose connection especially on the non-used side, then increase to predetermined pumping rate.
- Check sounding of filling tanks frequently , use ullage method.
- Regular check for oil trace from connections and ship side discharge . If any leak is found , stop bunker immediately.
- Essential to slow down when 80 % of total quantity and to be stopped at 85%.
- Let all valves open for some duration to expel the air from tank.
- Avoid spillage when connecting or disconnecting the hose.
U.S.C.G Regulations
- Bunker plan must be drawn up . All crew to be explained total bunker quantity , distribution plan , filling sequences. Engine room staffs to be assigned each and individual duties regarding bunker. This plan and assignments must be posted at bunker point.
- All bunker tanks must have vent pipes with flame trap head and spilled oil container of 1 Barrel Quantity to be placed near vent pipes.
- Chief Engineer must prepare necessary paper forms and to be signed prior to bunker as per procedures to regulations.
Fire Prevention
- Bunker oil flash point must not be less than 65’C under any circumstance as a rule.
- Ensure no oil leakage.
- No naked light or smoking is allowed in the vicinity.
- Keep fire stand-by watch with portable fire extinguishers.
How to minimize the shortage.
- Take exact reading of draughts and list to calculate trim of the ship. Keep vessel up right as possible.
- All tanks to be sounded . Calculate on board balance condition and plan the distribution.
- Avoid mixing the bunker from different origin.
- Check specifications of bunker , temperature , flash point , viscosity , specific gravity ,…. ect., according to delivery order.
- Take soundings of bunker barge using water finding paste .
- Record time of commence and completion , pumping rate .
- Take final soundings of total bunker by using water finding paste , calculate receiving amount of bunker by using volume correction factor as per A.P.I and gravity with exact temperature.
- Call bunker surveyor through agent for any dispute.
After bunker
- Take 3 sample bottle , one for ship , one for analysis and another for bunker supplier. All samples to be sealed ,with both ship and barge ‘s stamps , date , place and signs of Chief Engineer and supplier.
- Check delivery receipt , describing amount and specifications to be the same with delivery order. Then chopped and signed. At least 2 copies of receipt to be kept for ship. One for F.O report to Head Office and one for ship file.
- Log to be enter official and actual receipts. B.O.B at this moment to be mentioned. Inform bridge.
- Oil Record Book to be entered with correct code no., item no., date, place, exact time of commence and completion, added and total quantity of tanks with number, and signed.
How to take sample and requirements.
- Sample must be taken by continuous dripping method . The sample to be drawn from bunker line by using of dripping probe or drain valve crack open for dripping at oil pump out let from barge.
- Sample bottle is 1 ltr capacity. If tin container it must be 4 ltr capacity.
- Sample oil bottle is to be sealed in front of Chief Engineer or other witness.
- On the seal the following to be provided.
- Place and date of bunker sampling
- Method and place of drawn
- Name of barge
- Name of ship
- Quantity and grade
- Name of Chief Engineer and Supplier
- Signs of them
- Samples to be taken 3 bottle. One for ship , one for analysis and another for supplier.
- Sample should be kept on board not less than 30 days from date of bunker receiving or until the bunker is totally consumed.
Bad Bunker
Bad bunker is caused when taking two different fuel oil within a specifications but a heavy sludge precipitation and not fit for further use. It may effect the Engine the following problems.
- High exhaust temperature
- Burning exhaust valve
- High combustion pressure
- Blow by and fire in scavenge
- High wear rate of engine parts
- Decrease performance
- Clogging of fuel system
How to minimize to receive bad bunker
- Order to standard marine fuel oil supplying contract
- Specifications must be complied with engine maker’s recommendations.
- Bunker may be refused if in doubt regarding specifications.
- Try not to mix bunker from different origin. Store in a tank having no oil remains.
- Proper sample to be drawn , sealed and taken.
- Sample to be analyzed by renown company.
- Sample to be kept on board till oil is totally consumed.
- Try not to burn as possible , before receiving lab report.
How to use bad bunker oil if No-way
- Sludge dispersion chemical to be applied to banker storage D.B and settling tanks.
- Applied heating to storage D.B ,settling and daily service tanks at temperature well above its pour point for separation of water and other impurities. Frequent draining practice to be followed.
- Use double stage purification method with slow feed rate. ( Purifier & Clarifier in series operation ). Frequent Desludging process to be made. Cleaning of these centrifuges and their filters to be done more than normal routine.
- Chemicals to be added in daily service tanks to improve combustion.
- Filters in F.O system to be cleaned more than normal routine.
- Maximum permissible heating temperature to be applied to gain good viscosity control at visco-therm unit.
- In some case , raise the temperature of fuel and charge air temperature 5 ~ 10’C more , it may effective to avoid combustion delay and fuel knocking.
- While engine is running with bad fuel, the following factors to be keep close watch, and maintenance to be done:
- Exhaust temperature
- Cylinder and piston cooling temperatures
- F.O line and end heater temperature
- Visco-therm unit
- Charge air temperature.
- Turbocharger r.p.m
- Multiply the turbocharger water washing practices.
- Peak pressure indicator to be taken and check the engine condition.
- Fuel injectors to be cleaned and pressure to be tested
How to handle and maintain bunker oil
It is necessary to maintain and up grade the critical properties of bunker oil through the ship board process. These are consisting of the followings:
- Sediments settling process
- Filtering process
- Centrifuging process
- Mechanical process
- Chemical process.
The procedures for the above process are as follows:
1. Bunkers of different origin are stored in separate D.B. tanks. Coarse filters in bunker line is passed by the bunker oil while bunkering.
2. Heating is applied to storage D.B. tank to keep bunker oil temperature well above pour point and below flash point
3. Detergent type chemical additives should be dosed into the storage D.B. tank to prevent too much sludge formation.
4. Then , transferred the oil by pump with coarse filter, to settling tanks, which are having adequate heating arrangement and designed with slope bottom to improve contaminant draining. In this tanks , oil is settled and applied heating. Gravitational separation of oil from water and other impurities may occur and frequent drainage of them can be done. Oil temperature in this stage is kept not more than 60’C practically.
5. After settling out some water and impurities for about 24 hrs or more, the oil is fed to the separators passing through coarse filters in each unit again.
Double stage separation method by using purifier and clarifier in series with heater is promoting separation effect. All the contaminants and water are separated off during these process and almost clean oil is led to daily service tank which is same designed and arrangements provided as settling tanks.
6. Some firms are making finishing touch process at this point which are include several filters, Ultrasonic or Mechanical Homogenizer and Emulsifiers.
7. At the daily service tanks, by applying heating and maintain oil temperature about 60’C practically gravitational separation occur again. Then some remaining water can be drained out if any. Chemical for combustion improver can be dosed. At this stage , the oil is well processed and ready for use.
8. For burning process, the oil is drawn by booster pump from daily service tank to closed mixing column via coarse filter. From there the circulating pump feed oil to end heater to give correct injection viscosity control by Visco-therm unit. piping from end heater to fuel pump and injectors are provided with heating arrangement, and heated oil is led to pass through back flush filter which having filtering capacity up to 1 micron particles.