MIL-STD-186 Protective Finishing For Army Missile Weapon SystemsThis standard establishes the minimum requirements for procedures, materials, and systems for cleaning, plating, painting and finishing metals, wood, electronic materials, parts and assemblies for rockets, guided missiles, and components to protect them from deterioration.

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MIL-STD-186F (MI)

chemical or electrochemical methods, shall be stress-relieved prior to cleaning. Parts which may have high sustained tensile stresses as the result of assembly, or crevices which can retain cleaning solutions, shall be cleaned prior to assembly.

4.7 Organic soil removal. Organic soil shall be removed using a cleaning procedure appropriate for the contaminants and parts to be finished. Cleaning procedures include but are not limited to: pressure washing, immersion, hand wipe, ultrasonic, and vapor degreasing. Cleaning materials must meet appropriate OSHA and EPA standards.

4.7.1 Recommended cleaning materials. Cleaning materials are chosen on the basis of the effectiveness of contaminant removal, inertness to substrate material, and environmental compatibility. Vapor degreasing materials include but are not limited to: Hydrofluoroethers and Hydrofluorocarbon (HFC's). Hand wipe and immersion cleaners include but are not limited to: Acetone, Isopropyl alcohol,

volatile methylsiloxanes (VMS), mineral spirits, Naptha and MIL-PRF-680. Pressure washing cleaners include aqueous and non-aqueous materials. The EPA SNAP list should be consulted for a list of environmentally acceptable cleaning materials.

4.8 Painting. Unless otherwise specified herein, interior and exterior surfaces of the weapon system shall be primed and painted.

4.9 Plating. All plating with the exception of nickel, chromium, gold, palladium, platinum, and rhodium shall receive a supplementary treatment such as phosphate, chromate, wash primer, varnish, or conformal coating.

4.10 Metal coupling compatibility. Metals in contact, exhibiting a potential difference greater than allowed by table IX & X, shall be avoided. If dissimilar metals are necessary, such galvanic couples shall be protected with compatible platings, paint, insulating tapes, or sealants.

4.10.1 Reduction of corrosion at faying surfaces. To prevent corrosion at faying surfaces, particularly joints of corrosion resistant steel, under washers, and at fasteners where there is a lack of oxygen, such faying surfaces shall be sealed with polysulfide, polyurethane, epoxy, silicone rubber, wet primer, or similar sealant as specified in table V.

4.11 Weapon system prohibitions. Unless otherwise specified herein, the following materials and techniques shall be prohibited in the design of missile weapon systems:

(a) Design Prohibitions:

1. Crevices susceptible to moisture collection.

2. Unsealed fasteners and joints.

3. Galvanic metal couples with over 100-mv potential difference.