World Bunkering >Articles > Testing > Understanding global trends

Dr Vis

Bunker fuel testing is no longer a mere “testing and announcing the results” type of activity. There needs to be an understanding of global trends. Also required is adequate documentation and archived data to be able to present deviation from the norm, new patterns emerging and fresh problems that have arisen.

Not only this, bunker-testing agencies should carry out additional tests to ascertain possible problems with the fuel. Routine testing to meet ISO8217 is not enough. In fact, most of the problem fuels meet ISO8217 but they cause enormous problems in marine engines. Another point to consider is the quality of the testing. It is imperative that all the labs located in different parts of the world should give results that are very close to each other so that the shipping community will have confidence in the lab testing process.

With the presence of so many contaminants and the problems associated with sampling, there are enough reasons for the results to vary. Additional variation due to individual lab performance will only complicate matters further. It is, therefore, better to have the lab certified to the highest quality ISO17025 and the performance of individual instruments certified.

The implementation of MARPOL Annex VI has meant that more and more low-sulphur fuels are entering the market. Unfortunately, labs are seeing certain deterioration in the quality associated with reduction in sulphur content (such as increased catfines etc). Labs are also seeing some strange contaminants, which were not seen before (such as phenols from shale oil). It would appear that the refineries are still playing with process changes in order to provide low-cost, low-sulphur fuel.

Recently Viswa Lab detected the presence of strong acid number (SAN) in six samples. All of these showed presence of inorganic acid with SAN greater than zero. ISO8217 does not permit the presence of inorganic acid; SAN should be zero. While Viswa Lab recorded the presence of SAN, some of the other labs recorded zero. A detailed analysis of the method and procedures revealed that when following the ISO8217 recommended method for SAN, namely ISO6619, tests did show the presence of SAN.

However, those labs that followed the latest ASTM method (not the one recommended in ISO8217) showed zero SAN. Viswa Lab has also pioneered the testing for Mercaptan sulphur and H2S under actual working conditions and seen the evolution of H2S. This has helped in explaining stress corrosion damage while using fuels from some parts of the world.