WSS Warns On Wax Build Up When Using Low Sulfur Fuels

Jonas Ostlund and Sachin Gupta of WSS say that effective use low sulfur fuel for ECA compliance requires knowledge of the cold flow characteristics of distillate fuels.

Jonas Ostlund and Sachin Gupta of Wilhelmsen Ships Service Ltd (WSS) say that harmful paraffin wax build up in marine engines when using low sulfur fuels, which are increasingly being utilised for Emission Control Area (ECA) compliance, can be avoided with proper knowledge of the cold flow characteristics of distillate fuels, as well as techniques to prevent the formation of paraffin wax in cold temperatures.

Distillate fuel contains wax particles, known as paraffins, which are pulled together in colder temperatures, creating waxy masses that can collect on fuel tanks and clog filters, explains Gupta, adding that "as temperatures drop the wax problem increases."

With wax build up capable of causing both damage and loss of power (LOP) incidents in marine engines, Gupta warns that "prevention of this waxy sludge is much easier than finding a cure."

Three Stages of Wax Formation

Ostlund and Gupta explain that of the three phases of wax formation, Cloud Point (CP), Cold Filter Plugging Point (CFPP), and Pour Point (PP), CP is both "the first and final warning."

Gupta says that CP, the point a which formed wax particles become visible in the fuel in the form of clouding or hazing, "gives a very clear indication that action has to be taken."

CFPP is said to be the "point of no return," when wax crystal build up prevents fuel from passing through the filter, starving the engine of fuel, and creating a loss of power before PP is reached - the point at which the fuel solidifies.

"A key issue is that fuels with only slight differences of the same grade can react very differently at cold temperatures - with some flowing freely, while others have catastrophic effects on fuel filters.

"It's therefore vital to have a clear picture of both the temperatures vessels will be operating in and the characteristics, quality and specifications of the fuel you intend to use," warns Ostlund

Prevention

Gupta explains that one way to help in the prevention of wax build up is to use distillate fuel treatments, noting that while they do not alter cloud point, treatments can extend CFPP and PP points, postponing wax crystal formation.

"This kind of treatment represents a minimal cost for maximum peace of mind when it comes to cold climate operations," said Gupta, noting that treatment use will allow for more operation time and reduce the need for constant and close monitoring of the fuel.

Whether treatments are used or not, Ostlund suggests that crews and shipping firms should be aware of pre-defined CP and CFPP figures for the specific distillate in use, and ensure that they are familiar with the use of sounding tape and a sounding pipe in order to measure and analyse the fuel condition.

"Although this is a rather crude method of assessing fuel, it is the only quick and convenient solution, due to the fact that its otherwise difficult to visually check fuel that is enclosed in bunker tanks," said Ostlund.

"This kind of disciplined, well-informed approach really is the foundation for trouble-free sailing."

Last year, BIMCO issued a warning for members to be careful of paraffin wax forming in LSMGO in seasonally low temperatures.