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Fuel testing agency Veritas Petroleum Services (VPS) has issued a bunker alert to industry participants relating to highly abrasive fuels in New York.

It is the fifth abrasive fuel warning to be issued by VPS this year - the other four being for Amsterdam, Kaohsiung, Port Louis and Singapore.

Highly abrasive particles

Hard aluminium and silicon oxide particles - known as catalytic fines (cat fines) - find their way into the fuel during the catalytic cracking process in the refinery.

The fines are aluminosilicate zeolite catalysts that, depending on the catalyst used, vary both in size and hardness.

If not reduced by suitable treatment, the abrasive nature of these fines can damage the engine - particularly fuel pumps, injectors, piston rings and liners.

ISO standards

In ISO's 8217:2005 standard, the maximum permissible level of cat fines, measured as aluminium + silicon (al+si), is 80 milligrams per kilogram (mg/kg) - or parts per million (ppm) - for fuels ranging from 30 centistoke (cSt) to 700 (cSt). This comprises RMA 30, RMB 30, RMD 80, RME 180, RMF 180, RMG 380, RMH 380, RMK 380, RMH 700 and RMK 700.

In 8217:2010, ISO introduced a 20 mg/kg reduction to 60 mg/kg for RMG 180, RMG 380, RMK 380, RMG 500, RMK 500, RMG 700 and RMK 700, whilst the upper limit for RMB 30, RMD 80 and RME 180 was lowered to 40, 40 and 50 mg/kg, respectively. RMA 10 was set at 25 mg/kg.

The aforementioned maximum levels have been maintained in the subsequent 8217:2012 and 8217:2017 standards.

Manufacturers recommend 15 mg/kg

Engine manufacturers generally recommend a maximum of 15 mg/kg level of cat fines in the fuel entering the engines. However, as this figure is significantly lower than those specified in ISO standards, ship operators are advised by parties such as marine insurers to ensure adequate fuel handling and purification equipment and procedures are in place on board to effectively bring the levels of cat fines in the fuel down to below 15 mg/kg.