Marine fuel oil is one of the most important aspects that control the overall efficiency of ships and the shipping industry. The high cost of marine fuel oil requires maritime professionals to bunker, store and use the Heavy Fuel Oil, Diesel Oil and Marine gas oil very carefully and exercise due diligence in keeping track of the consumptions meticulously.
Mentioned below are few points that must be noted to ensure economic use and efficient storage and bunkering of fuel oil on board ships:
1. On many older vessels, the HFO flow meter does not function correctly (in many cases the return oil flow meter is either not provided or not functioning correctly) and is not being regularly serviced and calibrated. Maintenance of HFO flow meter should form a part of the PMS and Continuous machinery survey to underline it’s importance. Have you ever noticed a surveyor asking to find out how your flow meters are working and are you regularly cleaning fuel oil flow meter filters on main engine and generator fuel lines? In some cases in the past black out was caused because generator fuel oil filter ( smaller in size and by pass closed) was not at all cleaned.
2. Understanding the correct procedure for bunkering is extremely important for the safety of the vessel and for preventing oil spill. Companies and port authorities must also provide necessary training and guidance to ensure safe bunkering procedures. For e.g. Maritime and Port Authority of Singapore have issued good instructions and guidance notes for bunkering at Singapore and these should be studied and followed. Quality has rarely been an issue involving Singapore bunkers but at times we do come across disputes involving quantity largely due to Air blowing and what we commonly know as “cappuccino bunker”.
On my last ship, we were taking most of the bunker in (double bottom) DB tanks but some 50-60 tonnes in the end in wing tank to eradicate air-blowing effect, if any. But such a tank arrangement may not be there on other ships and in that case we can ask the barge to blow air after we have taken the soundings.
3. Sounding pipes must be used properly to prevent errors in tank readings. In many cases we are not able to properly put the tape in the sounding pipes resulting in erroneous readings. If the sounding pipe is straight, using a rod (a nut welded to the end to fasten rope) is quite effective to take ullage especially in cold climates. Also, in some cases the calibration booklets are not very correct on certain trim conditions and thus the quantity cannot be gauged correctly. Ensure to avoid such problems. It is a good practice to put some diesel oil (1-2 liters) in the sounding pipe of HFO tanks 1 day prior to scheduled bunkering especially in cold region.
4. It is good to know the tank characteristic from experience of previous crew as well and record of regular soundings and quantity determination kept in computer, which normally convinces the off/on hire surveyors.
MPA Singapore are in the process of making bunker barges to install approved flow meters employing modern technology to ensure that ships get the correct quantity and there is no dispute. International Bunker Industry Association is also doing a good job in the matter of developing bunkering facilities at various ports around the world, both for HFO/LSFO, LSGO and LNG bunkering.
Singapore, Rotterdam, Fujairah and Houston are major bunkering ports for various quality of fuel oils while Rotterdam, Seinehaven, Port Fourchon in Louisiana and Shwinaouski in Poland are being developed for LNG bunkering.
5. Correct sampling and expeditious dispatch for fuel testing to laboratory must be done properly. Some disputes regarding quality have been reported in fuels picked up from a Ukraine port (water and total sediment potential) and some times from Houston areas. Ensure that the appropriate samples are sent to the shore lab for correct test results.
6. On bulk carriers, which carry powdery cargo, we must carefully examine the air pipes and sounding pipes which pass through the hatches (hidden behind structural protection) to see that there is no wastage and hole in them through which the cargo can find way to fuel in the tanks below. This aspect is commonly neglected these days.
7. It is also commonly found on many ships that tank cleaning on ships is not done at least once in five years (due largely to economic causes and dry dock availability). Moreover, it is also found that tank or tanks not being used on some ships are still carrying a remnant of about 15-18 tonnes. In many cases the heating coils are leaking and the sludge has been pumped into one of these tanks. Even the service and settling tanks are not being cleaned and internally examined once in five years. This is a grave issue and proper steps must be taken to ensure tank cleaning and inspection at regular intervals of time.
8. These days the quantity of diesel oil carried on board is quite less and if the vessel is in cold area for a long period, condensation of air in tank occurs. It is necessary to check D.O. tank drain and clean D.O. line filter to check the possibility of presence of water.
9. Indiscriminate mixing of fuels from various origins (Even if the grade, say, 380Cst, is same) also causes problems in usage of the fuel. Correct purification and filtration ensures good burning resulting in saving of fuel. Purifiers and filters should be cleaned regularly with due attention from a senior engineer.
10. Maintaining correct temperature and viscosity at injector 13-15 Cst ( temperature about 135 DegC for 380 Cst Oil) will ensure good burning and savings of fuel. We must ensure availability of 0.1% suphur content fuel at several locations. (IMO postponing Tier III requirements from 2016 to 2021 is a good move.)
11. By now, we have come to grips with problems associated with switching of fuel to Low Sulphur fuel and LSGO concerning lack of lubricity and leakages occurring at fuel oil supply and circulating pump shaft seals. The bacterial contamination of remnant LSFO (H2S formation) does occur if the fuel is held unconsumed for long and if the ship is not going to a SECA area any soon , it is justified to consume off this oil.
ISO 8217: 2010 is in force for fuel oil analysis and this takes into account the hydrogen sulphide, lubricity and oxygen stability. Lubricity and Oxygen stability tests will become more important after 2015, as we progressively use ultra-low-sulphur distillate fuels.
12. The air pipes and sounding pipes of F.O. tanks on decks should be checked to see that they are structurally sound and wire mesh on air pipes not damaged or clogged.
13. When we clean the exhaust gas economizer, the boiler pressure increases fast as we sail out. In such cases if our dump steam condenser is not kept clean, we tend to open too much steam into bunker tanks causing fuel oil tank high temperature alarms to sound. This may damage some cargo carried on other side of the bulkhead. Many times we do not operate or keep dump steam valve on auto because LT cooling water temperature rises (dump condenser LT cooled). We need to keep these possibilities in mind while carrying fuel oil.
14. Many a times we needlessly delay ships in trying to sort out the issue of quantity received. This also happens when the vessel is not able to determine correct trim and when she goes down by the head upon completion of bunkering. A balanced approach at such times helps to settle matter amicably. These issues will diminish in time as the suppliers (like WO bunkers and those supplying at Singapore) install technically sound flow meters on their barges as is reportedly being planned by MPA Singapore by the year 2014.
15. Lots of care is needed while bunkering and storage of fuel oil and we should realistically carry out pre-bunker meeting to discuss the bunker plan and safety aspects. The crew in the Deck department should also participate enthusiastically to tend mooring and to provide safe access to bunker man to board the ship, keeping a good watch on this arrangement ( like adjusting gangway, if being used) as the bunker progresses and the barge comes up.
Care and Re-checking are good habits in almost all operations and same is required for the bunker procedures. The role of Society of Gas As a Marine Fuel (SGMF) in encouraging safe supply and responsible operation of vessels using LNG as fuel is laudable.
International Bunker Industry Association (IBIA) is also doing a good job in involving itself in all aspects of fuel availability, fuel delivery to vessels and to its testing and use on board. If possible, shipping companies should become the members of IBIA to gain benefits by it’s research activities and useful publications.
These are some of the important practical tips for bunkering and storage of fuel oil on ships. Do you know any other important points? Let us know in the comments below.