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Find substitute for Methylene Chloride in depaint operations at Hill AFB


OBJECTIVE: Identify an effective substitute for MeCl that does not contain haz air pollutants & can not interfere with the metal removal process at industrial waste treatment plant. Substitute must meet mil-spec requirements for landing gear maintenance. DESCRIPTION: Methylene chloride is a regulated OSHA toxic and hazardous substances as well as a hazardous air pollutant (HAP) under the Clean Air Act. Landing gear maintenance facility at Hill AFB services aircraft landing gear, brake and wheels. Due to complex geometry of the variety of landing gears, wheels and brakes paint on the components is difficult and very labor intensive to remove. Current practice of dipping parts in methylene chloride solution to loosen paint adhesion followed by plastic media blast, although effective and efficient, uses over 16, 000 gallons per year of methylene chloride based stripper. Replacing methylene chloride with more environmentally friendly alternatives will enable the base operation to eliminate the use of methylene chloride based solvent, provide a safer environment for the workers, and significantly reduce the emission of HAPs. The suitable substitute must remove the paint/grease more effectively then the methylene chloride process. The substitute must also be shown to be safe on landing gear parts made of materials such as aluminum alloys (for example 2014 and 7000 series) and high strength steels (for example 4340 and 300M). Among the properties to be test for safety are corrosion, hydrogen embrittlement and fatigue. If removal can be achieved chemically without having to blast with media afterwards, we have achieved our goal. Production time is also factored into this acceptance, due to the volume of parts being handled; we must find a replacement that will work within current time frames to ensure we do not impact production. PHASE I: Potential substitute(s) will be identified specific to Hill's production needs. This will include evaluation of substitute process requirements in comparison with current process, meeting Technical Order and Mil-Specs for landing gear paint removal activities, laboratory scale testing of efficiencies, bench testing of compatibility with substrates and compatibility with IWTP"s treatment process. PHASE II: The substitutes identified in Phase I shall be tested to show their safety with landing gear materials. During phase II, substitute(s) identified in Phase I will be studied in a prototype production line at the maintenance facility using condemned parts. Parameters evaluated in Phase I will be expanded and operational data will be collected to demonstrate the production and economic feasibility of the substitutes (high strength steel, aluminum alloys). PHASE III: Phase III will see the full scale implementation of substitute process at Hill AFB landing gear maintenance facility and recommend other potential applications on base. REFERENCES: 1. AFRL/CTC's report on Non-acid Based, Alternative Paint Strippers to Methylene Chloride, April, 2012. 2. ASTM 519. 3. TO 4S-1-182. 4. TO 4W-1-61. 5. TO 1-1-8.
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