The Army, Navy, Air Force, and Special Forces along with other military organizations have mandated the elimination of ozone depleting chemicals (ODC). Unfortunately, most of the military’s small- and medium-caliber ammunition in the inventory uses solvent-rich, highly-toxic ODCs, such as 1,1,1-trichloroethane (TCA), in their sealant materials. It is essential that these materials be replaced with solvent-free or solvent-safe case mouth sealants.
The goal of this program is to eliminate and replace the series of ozone depleting case mouth sealants, for small- and medium-caliber ammunition with environmentally-safe alternatives. These materials also would be applicable for threaded and fitted material components such as fuzes.
Efforts were aimed at testing and documenting the compatibility, reliability, and durability of non-ozone depleting sealants that also met all of the ammunition acceptance requirements. Promising candidates then were subjected to functional testing and characterization as well as numerous acceptance evaluations. The initial selection of commercial materials was based on a study of mechanical, chemical, and physical property data as well as manufacturer recommendations.
An industry search was conducted into potential alternatives, and “fast track” testing was conducted. More than 50 candidates were down selected based on application ability, and the best candidates under went chemical analysis. Through the down selection process, Hernon 34201, a waterborne asphalt (paraffin) modified with a styrene/acrylate copolymer with plasticizers/fillers, was chosen. The material behaves similarly to previously existing sealant materials. Weapon compatibility, reliability, and durability testing was conducted for Hernon 34201. The project was completed in FY 1996.
Through the use of this technology, significant amounts of sealants with ozone depleting, toxic solvents, such as TCA, keytones, etc., would be eliminated, yielding a notable environmental benefit. As an example, the yearly usage of ODC sealants that would be eliminated at the Lake City Army Ammunition Plant in Independence, MO, is estimated at 2,000 gallons of TCA (5.56mm, 7.62mm, and .50 caliber rounds) and 700 gallons of other assorted ODC solvents (20mm rounds). Economic benefits would include reduced costs (elimination of toxic ODC environmental protection activities), increased production rates, reduced scrap ammunition (estimated at $2 million per year), and reduced lot rejection rate (which averages 6 percent annually). Other benefits would include reduced ODC health and safety problems, reduced misfires and hangfires, decreased damage to weapon systems and vehicles, and improved personnel safety.