The Navy has two, separate and documented incidents of diesel fuel, when compared to other fuel tested in accordance to ASTM D5304 should have been stable for at least 2 years. However, within months the fuel was rapidly degrading, forming sediments and darkening in color. In both of these incidents, the fuels contained stability additives. A summary of the incidents are provided below. Background: The Navy procures F-76 fuel according to MIL-STD-16884. Section 1.1 of ASTM D5304 states that the procedure is for assessing the potential storage stability of fuels such as Grade No. 2D in accordance with ASTM D975. F-76 fuel meets the specification requirements of Grade No. 2D diesel fuels in accordance with ASTM D975 with the exception of sulfur content. The storage stability requirement for F-76 is 3.0 mg/100 mL (max) when tested in accordance with ASTM D5304. Fuel meeting this requirement is typically stable for at least two years. Rapidly Degrading Fuel 2004 The F-76 specification in 2004 allowed for the use of stabilizer additives meeting QPL-24682. In 2004, multiple ships reported extremely high filter change rates, causing the Navy Fuels team to investigate the source fuel. It was found that F-76 fuel procured by the Navy in 2004 failed storage particulate requirements in as little as 60 days from production. This fuel came from one supplier and contained a stability additive. Laboratory testing demonstrated that the additive caused false passes of ASTM D5304. The additive slowed down the reaction process, but did not prevent particulates from forming. Additionally, it was found that the dispersant portion of the stabilizer additive was the cause for the false stability passes. Detailed data analysis can be found in section 4.0 of attachment 1. Rapidly Degrading Fuel 2011 The F-76 specification in 2011 prohibited the use of stabilizer additives. F-76 fuel procured by the Navy in December 2010 met specification limits, however, after two months of ambient storage, the fuel contained significant amounts of visible sediment. After multiple ship complaints of excessive filter clogging, multiple samples were analyzed. Elevated nitrogen levels were found amongst the fuel samples and the source of all the fuel could be traced back to one supplier. Upon questioning, the supplier admitted using a storage stability additive. Detailed data analysis can be found in attachment 2. Conclusion: Based on the detailed analysis conducted in 2004, it was demonstrated that the presence of stabilizer additives dramatically reduced the result of ASTM D5304, yet samples contained high levels of particulate after as little as 60 days. Additional testing demonstrated that the dispersant portion of the stabilizer additive was the major contributor to the reduction of the ASTM D5304 result. Based on the results of this analysis, in 2006, stabilizer additives were prohibited in F-76 (MIL-STD-16884 rev L). In 2011, similar trends were seen with passing storage stability results, yet samples quickly formed fine sediments. The supplier reported adding a stabilizer additive to the fuel in this instance as well. Fuel received between 2006 and 2011 passed ASTM D5304, did not contain storage stability additives, and remained stable for over 2 years. Based on the technical analysis of the above two cases, we request ASTM D5304 be revised to state that it is not valid for use on fuels containing stability additives. The following two attachments can be found in the WK 45493 collaboration area. Attachments: 1. Williams, Sherry. Engineering Investigation of 2004/05 East Coast F-76 Rapid Fuel Degradation. NAVAIRSYSCOM REPORT 4451/06-006. August 14, 2006. 2. Turgeon, Ryan. Analysis of East Coast F-76 Rapid Fuel Degradation. NF&LCFT Whitepaper. August 18, 2011.
Keywordsdistillate fuels; fuel insolubles; oxidative stability; oxygen overpressure; stability; storage stability; Distillate fuels; Fuel insolubles; Middle distillate fuel storage stability; Oxidative stability; Oxygen overpressure; Storage stability--petroleum products;