Traces of water in bunker fuel are normally very low at about 0.1-0.2% by volume.
ISO 8217:2010 Fuel Standards for ‘Marine Residual Fuels’ gives the maximum allowable water content to be 0.5 % v/v.
Water can originate from number of sources like heating coil damage causing leakages and tank condensation; however deliberate injection cannot be ruled out.
In case large quantity is found then a letter of protest should be issued immediately.
However, the exact quantity of water can only be determined after the settlement phase where the water would have settled down at the bottom of the bunker tank.
High water content causes other issues like removal costs to ashore if the OWS (Oily Water Separator) onboard is not able to filter it out and also reduces the fuel’s specific energy
Fuel samples provided by the barge may not have any traces of water as the samples may have been taken prior to bunkering and mixing of water. Always ensure that the fuel samples are collected during bunkering and not before or after. For these reasons never sign labels in advance or sign for samples of unknown origin. Samples should only be signed for those actually witnessed.
Use of water-finding paste on the sounding tape is good for distillate fuels only and does not work with residual fuels. Even incorrect type of ‘water-detecting’ paste could be used.
On-site testing should be done for water-in-oil test. It may be not viable for the ship operators to invest in high end equipment for such purposes but as a minimum the vessel should be able to test a bunker representative fuel sample for water, test for density and compatibility.
Remember whenever in doubt or have concerns always issue a letter of protest.
Kaivan H. Chinoy is the Founder and Principal Marine Surveyor of AVA Marine Group, owners of Petro
Inspect and The Bunker Detectives.