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Attention to Acceptance or Rejection of Fuel Oil - Cargo ships Bunkering procedure

Due to its low cost, most large cargo vessels are powered by bunker fuel, also known as Heavy Fuel Oil, which contains higher sulfur levels than diesel. The fuel oil releases energy to rotate the ship propeller or the alternator by burning fuel inside the engine's combustion chamber. It also helps to generate steam inside the boiler.

Accepting fuel oil for ship use needs some careful consideration since poor quality fuel can cause ships main engine fuel system operational problems, such as purifier or filter clogging, fuel pump scoring or failure, severe cylinder liner wear, fuel injector seizure, exhaust valve seat corrosion or blow-past and turbocharger turbine wheel is fouling. Above is just a shortlist of potential problems. Ships chief engineer should apply his best judgment before deciding to accept or reject bunker fuel oil. The following guideline might be useful in this respect.

containerships operational matters
Oil Tanker Safety Guide
Difference in viscosity:
  1. If the deviation falls within the range allowed by the vessel side, the FO may be accepted in principle.
    Note: The allowable range for viscosity shall be, talking the machinery specifications, heating specifications, and specifications of auxiliary machinery that burns C-oil only talking into consideration; an upper limit of 200 CST or so to 180 CST in the machinery specifications, an upper limit of 300 CST or so to 280 CST in the machinery specifications, an upper limit of 450 CST or so to 380 CST in the machinery specifications.

  2. If the deviation is out of the range allowed by the vessel, the Chief Engineer shall refuse the receiving in principle, and shall make the supplier rearrange the type of Fuel to meet the order, if time permits. In this case, the time required for the re-arrangement and the following FO loading shall be confirmed after consultation with the local agent.

  3. If there are significant differences in viscosity, Chief Engineer needs to consult with the shipowner Fuel Section immediately. A decision to accept can only be made after receiving approval. A suitable letter of protest to be issued to the bunker supplier. It will be helpful resolving dispute.

Difference in Sulphur content
  1. The chief engineer should be meticulous regarding Sulphur content in a Bunker Delivery Note. IMO global sulfur limit of 0.5% should be strictly complied with in all cases. Any non-compliance, the Chief engineer should refuse to load and request re-arrangement.

  2. In the above case, the Chief Engineer shall inform the Fuel Section of the matter through the Master without delay and discuss whether the FO in question is to be received or not.

Excessive density

The upper limit of density should fall at 0.9910kg/m 3 at 150C(0.9916kg/m 3 at 60F), (according to ISO Standard). Therefore, if it is discovered by the confirmation made on the document before the loading that the density exceeds the upper limit, the Chief Engineer shall postpone the receiving and report the fact immediately to the shipowner Fuel Section and the Chief Technical Superintendent. A final decision can only be taken after receiving instructions.

For rules and standard on qualities of marine fuel oil, refer to the attached Specifications of Marine Fuels, ISO 8217, 1987(E) .

Excess or shortage in volume

If it is discovered by the confirmation made on the document before the loading that the loaded volume exceeds the ordered volume, the Chief Engineer shall refuse to receive the excess. In this case, the Chief Engineer should have the supplier accept that the vessel side shall make the judgment of the timing and the order to stop the pump after the loading of the planned volume, which an agreement shall confirm procedures in writing between the parties.

Furthermore, if it is discovered by the confirmation made on the document before the loading that the loaded volume is less than the ordered volume, the Chief Engineer should take the following measures:
  1. The Chief Engineer shall make the supplier rearrange the deficiency immediately if time permits. In this case, the time required for the re-arrangement and the following FO loading shall be confirmed after consultation with the local agent.
  2. Re-arrangement of deficiency may not be possible if there is not enough time. However, if the total remained fuel oil onboard is sufficient for safe navigation of vessel until the next port where refueling is possible such bunkering may be accepted in principle. In such case, the ordered volume shall be entered in remarks column on the bunker receipt, and the Chief Engineer should discuss with the owner where the deficiency is supplied or whether the supply is required or not, without delay.
    The chief engineer should judge the total volume of remained FO on board the vessel, and the newly loaded FO to the safe navigation of the vessel to another port where refueling possible. If a deficiency is found in newly loaded fuel oil, there is no time to rearrange the deficiency, and ships total ROB insufficient to reach the next bunker port, the chief engineer should report immediately through the Master the situation to the owner to seek further guidance.

In such a case, the Chief Engineer should include in the report information about the expected delay of the vessel on possible re-arrangement of the following refueling. Local agents and bunker suppliers should be in coordination to minimize the delay.

Determining H2S

All cargo vessel types need to have sufficient measuring instrumentation onboard. It was found H2S is most accurately measured using Draeger tubes (Type 2a). Draeger tubes are less prone to inaccurate readings due to cross sensitivities with other substances than electronic meters. A vessel with ten tanks or more may use a large number of tubes if testing two, three or more times.

It is now common to have a standard H2S Clause in a charter party fixture. The penalties for breach of Terminal regulations and C/P Terms are severe, both financially and commercially.

For guidance the Shell H2S Clause as follows:


In addition INTERTANKO note on H2S as follows:

While the dangers relating to Hydrogen Sulphide (H2S) are not new, there is a a growing body of evidence suggesting that H2S levels in some crude oils are on the increase. The reason for this apparent increase is unclear. H2S is known to be present in crude oil exported from several countries including Iran, Qatar, South America, Mexico, Poland, Latvia, Russia, and Turkey. Recently higher than normal amounts have been detected in Brent crude and within the last few days very significant amounts of H2S have been found in the ullage spaces of two tankers loading fuel oil cargo at Jubail in the Arabian Gulf.

Terminal operators should remain alert to the dangers posed by the presence of H2S, either within cargoes being delivered or remaining within the residues from a previous cargo. The precautions and procedures described within ISGOTT should be strictly adhered to.

The advent of Inert Gas and Closed Loading systems has largely negated the need to open tanks except for non-routine purposes, although reducing tank pressures to near zero for sampling is a relatively common practice. Purging for cargo preparation is also common, thus the planned release of the entire tank atmosphere, particularly where unexpectedly high levels of H2S are involved, poses a significant danger to individuals in the immediate and, in some cases, the not so immediate area. Some countries, particularly in Europe, have already stipulated maximum H2S levels in tanks before loading and some terminal operators have reduced their acceptable arrival levels from 10ppm to 5ppm.

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