Fuel System Inspections


Despite all of the advances in fuel system technology, regular physical inspections are necessary and required in most areas. The EPA publishes a UST Manual that covers the operation and maintenance of underground storage tanks. Broward County publishes Your Florida Petroleum Storage Tank Facility Inspection Guide that provides valuable information and guidance on what to look for when inspecting a fuel system. Regardless of where your system is located, both of these publications are helpful.

Part of the inspection process includes identifying water and corrosion problems. If they are present, then further investigation is required. Both indicate a potential problem with fuel quality. Simply adding fuel sampling to your inspection process can help identify and reduce serious issues. Purchase a bottom sampler from Dixon Pumps and start sampling your fuel today.

Noting water and corrosion issues without acting upon the problem will allow continued deterioration of your system. Once found, it is important to identify where the problem originates.

Bottom sample your fuel monthly – at least. If water is present, have it pumped out immediately. Consider using a biocide to protect your system from microbial infection. Microbes are a main source of system corrosion. Water is where they live. Keeping your system clean and dry is essential to reducing corrosion.

Microbial Influenced Corrosion

Microbes are living cells. There are two broad categories – aerobic and anaerobic. The majority of microbes affecting fuel are aerobic. That means they need oxygen to survive and multiply. Today’s highly oxygenated fuels supply the need. The process of removing sulfur actually adds oxygen to the fuel. Water contains oxygen, is necessary for microbial growth and is always present in fuel. It is virtually impossible to keep water out. As a result, microbial contamination is almost certain.

Microbes live off fuel. They are “hydrocarbon utilizing microbes – bugs” or humbugs as they are commonly known. They live in the suspended water, water vapor and water layers in the fuel. As they eat fuel, they produce acidic byproducts. Commonly found in fuel, acetic acid is a low-level acid that destroys metal in both the wet space of the tank and the dry space and vapor areas of the tank system. The result is corrosion. Other commonly found acids are formic acid, propionic acid and lactic acid. While there are others, these are the most prevalent.

All of the acids found in contaminated fuel cause corrosion, thus the term microbial influenced corrosion or MIC. All metal that is exposed both in the fuel and in the vapor space are susceptible to corrosion. MIC is a direct result of unmanaged fuel systems. Fuel cannot go unmanaged. Water levels must be continually monitored and immediately removed when found. Fuel sampling should be done on regular basis to identify the presence of water and other contamination. Fuel and tank cleaning are also a regular part of fuel management. Without a program in place, MIC will be a direct result.

What are the warning signs of MIC? For the fuel system owner, the signs are many. Below are some of the major warning signs:

  • Premature dispenser filter replacements
  • Corroded dispenser filters
  • Dispenser meter replacements due to corrosion
  • Corroded STP components
  • Frequent or repeated proportional valve replacement
  • Slow flow issues
  • Premature or repeated hanging hardware failures
  • Leak detector failures
  • Shear valve failure
  • Line and tank failure
  • Probe failure
  • What are the warning signs of MIC in engines and equipment?
  • Fuel injector failure
  • Faulty high pressure pump
  • Exhaust smoking heavily
  • Low compression
  • Engine runs rough at lower RPM
  • Engine does not start or is hard to start
  • Engine fails under load
  • Knocking or pinging issue
  • Fuel pump failure
  • Fuel filters clog prematurely or repeatedly
  • Fuel line failure

Whether a fuel system or an engine, the problem with MIC is serious and costly. Corrosion represents the single largest expense in the US economy, 6.2% GDP. For the fuel system owner, the liability of a potential fuel release is very real if fuel quality is not maintained. For the engine owner, failure is common. It has been noted that 90% of generators do not start or stop shortly after starting during an emergency. Over 75% of those engine failures are due to bad fuel.

Welcome to Dixons CleanFuel Blog

before and after sampleIn 2016, the EPA released their investigation on corrosion. In it, they say “corrosion increases servicing and equipment maintenance costs.”  For the power generation industry, this can mean increased maintenance by as much as 30%.  In the same study, they observed 83 percent of the inspected diesel fuel tanks had moderate to severe corrosion and less than 25% of the owners had any knowledge of it.

Cummins notes that the “wear of internal parts of the fuel system will decrease the life of the components and may even cause malfunctions that could result in severe damage to the other engine components.”  The picture above shows injectors pitted by corrosion caused by bad diesel fuel.  Diesel fuel is more susceptible to degradation than a decade ago.  Knowing the problems associated with diesel fuel creates a serious dilemma for every tank owner, especially those associated with backup power generation.  It is more important now than ever before to have in place a fuel quality management program.  A good program will include:

  1. Monthly bottom sampling of fuel.
  2. Quarterly fuel testing of samples.
  3. Immediate removal of any water present.
  4. Proper use of corrosion inhibitors and biocides.
  5. Yearly tank and fuel cleaning.

Without a fuel quality management program, you will have higher maintenance costs and possible liability issues because of damage caused by bad fuel.  Additionally, fuel economy can suffer by as much as 25%.  When Hurricane Sandy hit the Northeast, backup generation failed because of bad fuel.  Almost 75% of generators either failed to start or stopped shortly after startup.  Ninety percent of those that failed were due to bad fuel.  Fuel quality management is an absolute must.  Our CleanFuel blog is dedicated to bringing you the most up-to-date information on fuel mainenance issues and solutions.

“Bulk storage diesel fuel requires full filtering every six months to one year” Caterpillar