A Simple Guide to Cat Fines

Crucial to the cracking process in crude oil refining, cat fines assist in the breaking down of this commodity’s hydrocarbon chain, forming a major part in the process which results in the refined products we use all over the world. But what are cat fines? Find out…

SA Oil explains cat fines in fuel oil

What are Cat Fines?

Cat fines, or catalyst fines, are microscopic particulates often comprising aluminium (AI2) and silicon oxide (SiO2) molecules. Cat fines can vary in size; from about the size of a speck of dust to the width of a human hair. Their density also varies and can affect whether they settle in oil or not, though they are usually slightly more dense than heavy fuel oil molecules. Cat fines are also hydrophilic and will emulsify if they encounter water.

What are Cat Fines Used For?

They are used as catalysts during the distillation of crude oils in refineries, which improves the yield of high value products. These catalysts assist in ‘cracking’ or breaking down the molecules of crude oil – they break down the long hydrocarbon chains which make up crude oil into smaller chains, which can then be refined into products such as diesel, heavy fuel oil and gasoline.

Why Cat Fines Can Cause Problems

In an effort to abide by the ISO (International Organisation for Standardization) 8217: 2012 and the International Maritime Organisation’s strict regulations regarding marine fuel oil, refiners are trying to decrease the amount of sulphur contained within refined fuels. By 2020 crude oil refiners will have to ensure a low of 0.50% mass limit sulphur content comprises their marine fuel oils. Cat fines are often used to decrease the amount of sulphur in fuels but can pose a threat to machinery in the process if filtration is poor, which results in cat fines entering the fuel and causing abrasion and wear to softer metal engine parts like cylinder rings and pistons, as well as impact negatively on fuel pumps and injectors. The potential damage that cat fines can cause is so extensive, it can turn the level of damage which would usually take place over a year, into a matter of days or weeks. In an engine, any parts which came into contact with fuel containing cat fines would need to be checked and changed.

Engine makers specify a maximum of 15ppm (parts per million) of cat fines in fuel in order to protect the engine components. However, the ISO 8217 standards require a maximum of 60ppm, resulting in a large gap between what each party requires. Fuel containing only 15ppm cat fines is very expensive to make, so refiners usually comply with ISO standards, increasing the cat fine problem.

How to Protect Your Machinery from Cat Fines

There are several precautions that can be taken to reduce the chance of cat fine damage:

  • Regularly empty and clean storage and fuel tanks prior to fuel usage
  • Check fuel suppliers’ certificates of analysis
  • Sample all fuel before use
  • Ensure proper staff training
  • Install cylinder liners in engines, fuel purifiers and centrifuges to successfully separate the cat fines from the fuel
  • Keep to strict maintenance schedules in which storage facilities and machinery are checked and cleaned

Solving the Problem of Cat Fines

Prevention is better than cure, they say, and the saying goes in the case of cat fines. Purchasing cheaper, off-spec fuel may be enticing by its short-term savings, but sourcing higher quality, standard-conforming fuel from reputable suppliers can save you a fortune in the long run.

Reputable fuel suppliers conform to ISO and SABS standards and then some, offering a lower cat fine ppm ratio, resulting in better quality fuel that poses less of a threat to your machinery*. These suppliers will also provide certificate of analyses for their products, which detail the levels of particulates, like aluminium and silica, in each batch of fuel.  

*Machinery and equipment maintenance, and operating best practice still applies

Use A Quality Product from A Quality Provider

The long-term savings to be had from sourcing fuel from a reputable supplier greatly outweighs what you save from buying cheaper fuel. Avoid the costs – speak to the experts!