Cat fines in marine fuel
Catalytic fines are aluminium and silicon particles from refinery catalytic cracking that abrade fuel pumps, injectors and liners unless removed before the engine.
Catalytic fines, universally called cat fines, are hard particles of aluminium silicate carried over from a refinery fluid catalytic cracking unit into residual fuel. They are measured as combined aluminium plus silicon, and they cause abrasive wear of fuel pumps, injector nozzles, piston rings and cylinder liners when they reach the engine. ISO 8217 sets a bunkered limit for residual grades, and the engine builders set a much tighter limit at the engine inlet.
The full article will separate the two limits, which are routinely confused. The ISO 8217 figure is what the supplier must deliver; the engine-inlet figure is what the ship must achieve through settling and centrifugal separation, and WinGD states a maximum combined aluminium plus silicon of 15 mg/kg at the engine inlet in its fuel guidance. Achieving it is a function of separator throughput, temperature and water content, not of the delivered specification.
The article will cover the wear mechanism, the inspection findings that identify cat fine damage, the sampling point that actually tells a chief engineer what is reaching the engine, and why the distillate grades in ISO 8217 Table 1 carry no aluminium plus silicon row at all. It links to marine gas oil and heavy fuel oil .