Five Common Myths Associated With Treating Diesel Fuel That Every Fuel Manager Should Know
Authored By Bob Tatnall, Professional Engineer and Subject Matter Expert On Microbiologically Influenced Corrosion and Sludge in Diesel Systems.
MYTH 1: Good Fuel Quality will Prevent Problems.
ULSD is almost always of excellent quality when it leaves the refinery. The problem is that contamination happens during storage and transport - and this contamination is the source of many of our fuel system problems. Water (condensation and leakage) combines with common bacteria (who come with the water) to make sludge and biofilms - and this combination of biofilm and active bacteria leads to pitting corrosion. Sludge fouling leads to plugged filters and fuel lines.
MYTH 2: Biocides Will Sterilize the Fuel and Prevent Problems.
The bacteria that form sludge and corrosive deposits are a type know as "slime forming" bacteria. These creatures are difficult to control in the body using antibiotics - and they are likewise difficult to control in nature using biocides. Sometimes using a biocide triggers a reaction known as "mucoid stage" (i.e. "sludge formation on steroids") and there even are cases where bacteria have been able to convert the biocide to a "food" that promotes growth. Even in those cases where first treatment with a biocide seems to help, repeat or constant use of a biocide can lead to development of resistant strains. Biocides are, therefore, rarely a long term fix.
MYTH 3: Polishing Fuel will Filter out the Solids and Bacteria and clean the Fuel System.
Fuel polishing is most common in the marine industry and consists of a circulating fuel through filters to remove particles and suspended water and make the fuel look clean. Problem is, most of the slime, sludge and bacteria are attached to the walls of tanks and lines or stuck to filters. Removing the suspended stuff to make the fuel look clean does little to stop problems, and the fuel will quickly become ugly again unless the system is cleaned completely. A better and more cost-effective solution would be to use a system treatment that dissolves and prevents sludge and slime.
MYTH 4: Unstable Fuel is the Problem - use Stabilizers.
Fuel stability was a legitimate issue in yesterday's high-sulfur fuels. Today's ULSD is almost always rock-solid stable, and chemical stabilizers would be a waste of money. The exception is in certain modern extremerecycle engines that impart high pressure and heat stress on the fuel and can lead to filter plugging and black, non-slimy deposits in fuel tanks. There are chemical stabilizers that will prevent this, but most common additives that say they stabilize fuel do not work at all against this particular problem.
MYTH 5: Corrosion is NOT a Problem in Diesel Systems.
In fact, corrosion associated with biofilms in ULSD systems has become such a big problem that the petroleum industry has asked ASTM to form a task force to study cause and solutions. This insidious problem not only can cause leaking fuel lines and tanks, but also may damage tight tolerance surfaces in injector pumps, injectors, and metering devices. We have learned in laboratory studies that this issue can be prevented by using certain combinations of filming amine corrosion inhibitors.