Tanks for your service

MPI partners with the US Navy on new 500 Series tank lining standards

Some facilities have exposure environments

where abrasion, humidity, or marine/chemical exposures call for coatings designed for industrial service. And one of the most aggressive environments specifiers face are storage tank interiors, where the linings they choose must achieve two critical aims:

  • Protect the tank interior from the product stored inside the tank
  • Protect the product stored inside the tank from contamination by corrosion (rusting) of the tank interior

Water storage is a typical application for tank linings, but fuel storage tanks abound at facilities like airports and municipal fueling stations. And one particularly large owner of fuel storage tanks is the US Naval Facilities Engineering Command (NAVFAC), responsible for Navy shore facilities design, construction, and maintenance. The assets under their watch are everything on a Navy base, including Petroleum, Oil, and Lubricant (POL) storage and distribution systems.

The MPI 500 Series for Fuel Storage Tanks

With over 70 bases worldwide that can span areas up to 149,000 acres in size1, the navy owns a vast inventory of petroleum, oil and lubricant (POL) systems. These are considered among the most critical of land-based Navy assets in terms of a combination of risk from corrosion; the need for continuous direct support of base operations; and the life cycle cost-effectiveness of utilizing appropriate corrosion control systems.


Exterior corrosion such as pitting and surface erosion on above-ground POL facilities can occur due to atmospheric effects: temperature, humidity/atmospheric moisture, precipitation, salinity, topography, UV, winds, chloride deposition, sulfur dioxide deposition and other pollutants.


And internal corrosion can come from a variety of sources: condensation, hydrogen sulfide (H2S) evolution, the water dropping out of the fuel and sitting on the tank bottom for a long duration, and biological activity. Fuels such as biodiesel, low-sulfur diesel, and fuel containing high levels of ethanol can be corrosive.


Schematic of a typical fuel storage tank2

Proper interior protection is critical because iron rust in the jet fuel can cause restriction or clogging of fuel separators, silting and plugging fuel control components and nozzles, and wear and scoring of petroleum fuel components by abrasion.2 And corrosion of the tank shell can result in dramatic failure if perforation occurs.


500 Series Test Requirements Products that meet the MPI 500 Series must be a system consisting of a two-pack epoxy primer (MPI #500) and a two-pack epoxy topcoat (MPI #501). Unlike most MPI standards, paint suppliers who seek approval must submit both the primer and topcoat, and most tests are performed on panels coated with samples of both the manufacturer’s primer #500 and the topcoat #501 submissions.


In addition to rigorous performance testing found in MPI’s architectural standards, the 500 Series includes material-based requirements that impact personal and environmental safety as well. Products submitted must be free of lead and chromate, benzene, chlorinated compounds, or ethylene-based glycol ether and their acetates; have a maximum VOC of 340 g/l (2.8 pounds/gallon) and have a flash point (the temperature at which a particular organic compound gives off sufficient vapor to ignite in air.) below 95*F.


There are also requirements around ease of application, including Viscosity; Pot Life; Dry Time; Condition in Can, Storage Stability, Fineness of Grind. While these characteristics are useful to know, they don’t necessarily impact the product’s performance in the field.


Performance tests in the 500 Series include:


  • Knife test: we verify adhesion by measuring the coating system’s resistance to a cutting force
  • Reverse impact test: we measure the lining’s ability to maintain integrity and adhesion if the exterior of the tank gets dented. The uncoated side of the test panel gets hammered, and we check the coated side for cracking or any other loss of adhesion greater than 15 mm in diameter.
  • Fuel and water resistance: we immerse test panels for 21 days in glass jars containing a mix of JP-8 fuel and distilled water, and then check for blisters, darkening, or any indication of loss of adhesion (like softening).
  • Color: In MPI’s 500/501 system, the difference in color between the primer and the topcoat helps the inspector verify if the coating’s coverage is complete, which is far more crucial with linings for immersion service than paints for atmospheric service. In the 500 Series, the 500 primer is generally yellow while the 501 topcoat is generally an off-white. A required delta E of 10 or more between the two coatings means that the contrast should be easily visible to the naked eye for in-the-field application; any sections not visually distinct like this can indicate a thinness of the topcoat or otherwise incomplete coverage.

Invitation for New Product Submissions

MPI invites manufacturers who supply tank linings for jet fuel storage to submit products for testing under MPI 500/501: gaining MPI approval opens doors to do business with the Navy and other big specifiers and owners who source coatings from MPI’s Approved Products Lists. For more information, call Terrance Mayes at (740) 438-6608 or email Terrance at terrance.mayes@mpi.net.

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1. Data extracted from naval-technology.com and military.com
2. Excerpted from the Whole Building Design Guide, Petroleum, Oil, And Lubricants (POL) Storage and Distribution Systems Knowledge Area; Joseph C. Dean, P.E., and Steve Geusic, P.E.; updated 11-20-2019