MIL-STD-1411B
5.2 Serviceability inspection.
5.2.1 Residual gas and moisture control. Cylinders shall be inspected for residual gas pressure. The level of pressure shall be 5 psig, great enough to produce an audible hiss when the valve is slightly cracked open. Any cylinder suspected of containing water shall be inverted and drained of its contents for not less than 10 minutes, and shall be considered an open cylinder. Cylinders with low pressure, negative pressure, or with open valves shall be scheduled for cleaning and drying, or purging at maintenance, as applicable. If the audible hiss method is
used, a slip of paper shall be used to ensure that any sound is due to a positive pressure and not a vacuum when the valve is slightly opened. For general applications, a cylinder containing 5 psig of pressure from residual gas will be acceptable for evacuation and refilling. Cylinders such as acetylene, LPG, or fuel gas mixtures may be returned partially filled with gas that is of value to the government. This gas shall be retained and included with the cylinder tare weight to make
up the base weight for cylinder charging. All other cylinders partially filled with gas shall have their contents bled off and disposed of in accordance with current environmental requirements. The residual gas shall be considered waste by the government and may be reclaimed at the discretion of the gas supplier. Gases included are chlorine, anhydrous ammonia, and fluorocarbon refrigerants, as applicable.
5.2.2 External inspection. Each cylinder shall be inspected externally by placing the cylinder in a good light, tilting to reflect light, and slowly rolling for a complete revolution. The entire surface shall be inspected for excessive denting, pitting, gouges, bulging, or corrosion. Rejection shall be in accordance with the contractor's standard practice, but damage shall not exceed rejection levels established in CGA C-6. Particular attention should be given to identifying cylinders with an arc-burn generally found in the welding trade. Cylinders in helium, argon, oxygen, acetylene, or LPG gas service with an arc-burn shall be condemned because there will be a change in the crystal structure of the steel at the point of damage and immediately around the area. This type of damage is hazardous and cannot be repaired. Condemnation of the cylinder with an arc-burn is mandatory. Evidence of grinding out a defect on a cylinder after manufacture shall be cause for rejection. It should be noted that the manufacturers of high- pressure cylinders often grind the shoulder areas after necking to remove ridges or tooling marks solely for appearances. Some cylinder drawing processes are exposed to the atmosphere and oxides forming on the surface crack in cooling. These cracks show up in x-ray examination of the cylinder shell. A longitudinal grinding of several mils depth removes the offending oxide
and allows inspection of the base metal. These grinding marks will be exposed when the
cylinder is stripped and are identified by their longitudinal pattern, but are not cause for rejection or condemnation.
5.2.2.1 Paint inspection. The condition of the paint on each cylinder shall be inspected for peeling or chalking. The cylinder color shall be in accordance with MIL-STD-101 and the specific PID. Cylinders displaying a random pattern of chipping or peeling shall be stripped and repainted. Cylinders displaying localized chipping from a specific use pattern may be spot painted to seal the denuded metal. When a cylinder requires coverage of more than 10 percent of its area, stripping and repainting will be justified. Protective caps shall be considered a part of
the cylinder package to be repainted with a cylinder needing paint in the maintenance process.
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