TO 1-1-700 - Robins Air Force Base

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TO 1-1-700 3.9.10 Climate. Warm, moist air, normally found in tropical climates tends to accelerate corrosion; while cold, dry air normally found in arctic climates tends to reduce corrosion rates. Corrosion does not occur in very dry conditions. For this reason, desiccants are used in shipping containers to produce very dry local environments. The operational climate extremes have always been considered in equipment design. However, certain areas within electronics equipment, vans, and shelters, such as air-conditioned and/or cooled areas, may be subjected to climatic conditions very different from external areas. Relatively warm, dry air that has been cooled by air conditioners, thus increasing its relative humidity, and ducted into interior areas of equipment, vans, and shelters without drying or passing it through an expansion valve can release sufficient moisture to accelerate corrosion. It is imperative to consider not only the exterior operational environment but also the environments in which C-E-M equipment will be fabricated, transported, reworked, repaired, and mounted inside a van or shelter. 3.9.11 Desert. Hot, wind-swept deserts create a severe maintenance problem because powdery dust can penetrate even supposedly sealed components. High daytime temperatures, high humidity (in areas such as the Persian Gulf), ultraviolet radiation, and fine dust are the four most serious, destructive elements of the desert climate. Non-metallic materials suffer the most damage from the hot desert climates where air temperatures during the day may reach 124 °F (51 °C). Temperatures inside closed containers may be 100 °F (38 °C) higher than external air temperatures. 3.9.12 Temperate Zones. The temperate or intermediate climate zone encompasses most of the North American and European continents. At various times of the year, these areas may approximate the extremes of polar, desert, or tropical temperatures and humidity. The temperate zone temperatures range from -25 °F to +59 °F (-32 °C to +15 °C) in the winter and from +59 °F to +125 °F (+15 °C to +52 °C) in the summer. The relative humidity (RH) also fluctuates between five and 100%. The most critical areas are coastal locations during the warm periods of the year in which the relative humidity approaches 100% RH at night and the air has high concentrations of salt. Moisture from this salt laden air can condense on equipment during early evening and morning hours, thereby causing serious corrosion. Because of its relatively mild temperatures, the temperate zone is also the most heavily populated. Consequently the smoke, smog, ozone, and corrosive fumes associated with heavy industry are also found there. 3.9.13 Tropics. The greatest challenge to the C-E-M equipment industries is to design equipment that is protected from corrosion and deterioration in the heat and humidity of tropical climates. Even though they encompass only a small portion of the earth's land area, the tropics demand the greatest amount of consideration from the standpoint of corrosion treatment and control. Relative humidity of up to 100% RH at ambient air temperatures up to and above 85 °F (29 °C) create a formidable threat of corrosion. When high humidity and temperature conditions are combined with salt-laden air, the corrosive environment becomes extremely severe. The critical combination of high temperatures, condensation, high relative humidity, and contaminants such as salt and sand may cause catastrophic failure of equipment. Deterioration of the materials used in electronic equipment is also accelerated. 3.9.14 Factors of Influence in Tropical Environments. Tropical environments are noted for long periods of heavy rainfall during which 100 inches or more of rain may fall. Extended periods of high heat and humidity contribute to rapid corrosion of metals, cracking and flaking of rubber and plastic materials, and deterioration of seals. Equipment, whether stored or in use, requires special protective containers/measures and frequent preventive maintenance. Microorganisms multiply excessively in tropical environments and attack many non-metallic materials. Many items become covered with fungi in a matter of hours. Electronic equipment requires special efforts for effective operation in the tropics. Intensive preventive maintenance and the best possible protective techniques are necessary for C-E-M and associated equipment in tropical environments. 3.9.15 Manufacturing. During the manufacture, assembly, or repair of C-E-M and associated equipment, many factors that might lead to corrosion may be introduced. The use of unsuitable materials and improper materials processing can cause corrosion. Assembly of parts in areas contaminated by fumes or vapors from adjacent operations may result in entrapment of the fumes or vapors in the equipment which may cause future corrosion. Spaces that are air conditioned without humidity control may be sources of condensed moisture. 3.9.16 Storage. Even traces of corrosive vapors in packages containing electronic parts may result in serious corrosion. Moreover, the natural breathing of packages may introduce moisture into the parts and equipment. Some packing materials have been known to decompose and emit corrosive vapors during periods of prolonged storage. Refer to the equipment system specific maintenance manual for additional storage information. 3.9.17 Shipment. During shipment, materials such as plastics and lubricants are often exposed to environments that were not considered during the design stage. Materials shipped by air are subjected to changes in atmospheric pressure and can lose volatile components by out gassing. The vibration and mechanical shocks associated with shipment by truck can damage protective coatings or platings. Shipment by ocean vessel may expose the equipment to corrosive marine environments, vibrations and shock from engines or sea conditions, and residual corrosive vapors from previous shipments. 3-18
TO 1-1-700 Although packaging equipment in accordance with MIL-STD- 2073-1 will protect the equipment from corrosive environments, packaging may be damaged during handling and thus become ineffective. 3.9.18 Industrial and Ship Emitted Air Pollutants. Smog, smoke, soot, and other airborne contaminants are extremely corrosive to exposed C-E-M equipment. Many of the fumes and vapors emitted by ships and from factories can greatly accelerate metal corrosion. Industrial atmospheres may exist over large areas, since wind may carry these corrosive gases many miles from their source. Generally, air pollutants, when combined with water, create electrolytic solutions and accelerate corrosion. 3.9.19 Animal Damage. Damage to C-E-M and associated equipment may be caused by insects, birds, and various small animals, especially in tropical environments. Equipment in storage is most susceptible to this type of attack, since animals may enter through vent holes or tears in packaging and sometimes build nests. Moisture absorbed by nests plus excretions from animals may cause corrosion and deterioration that goes unnoticed until equipment is put into use and fails. Another type of damage may occur when organic materials, such as upholstery, are shredded for nests or consumed as food. 3.9.20 Microorganisms. Microbial attack includes the action of bacteria, fungi, or molds. Microorganisms are nearly everywhere and outnumber all other types of living organisms. Organisms that cause the greatest corrosion problems are bacteria and fungi. Damage resulting from microbial growth can result from: (1) the tendency of the growth to hold moisture which then causes corrosion; (2) digestion of the substrate as food for the microorganism; and (3) corrosion of the surface beneath the growth by secreted corrosive fluids. 3.9.21 Bacteria. Bacteria may be either aerobic or anaerobic. Aerobic bacteria require oxygen to live. They can accelerate corrosion by oxidizing sulfur to produce sulfuric acid or ammonia to produce nitric acid. Bacteria living on or adjacent to metals may promote corrosion either by depleting the oxygen supply or by releasing metabolic products. Anaerobic bacteria, on the other hand, can survive only when free oxygen is not present. The metabolism of these bacteria requires them to obtain food sources by oxidizing inorganic compounds such as iron, sulfur, hydrogen, and carbon monoxide. The resultant chemical reactions cause corrosion. 3.9.22 Microbial Growth Requirements. Fungi make up one class of microorganisms that feed on organic matter. Low humidity levels inhibit the growth of most species of fungi and bacteria. Ideal growth conditions for most fungi and bacteria are temperatures of +68 °F to +104 °F (+20 °C to +40 °C) and relative humidity of 85% to 100% RH. It was formerly believed that microbial attack could be prevented by applying moisture-proof coatings to nutrient materials or by drying the interiors of compartments with desiccants. However, even some moisture-proof coatings are attacked by microorganisms, especially if the surface to which they are applied is contaminated. Some microorganisms can survive in spore form for long periods while dry, and can become active when moisture is available. When desiccants become saturated, they form what is known as a “desiccant pump” which pumps their absorbed moisture into the affected area by evaporation and allows microorganisms to begin to grow. Dirt, dust, and other airborne contaminants are the least recognized contributors to microbial attack. Unnoticed, small amounts of airborne debris may be sufficient to promote fungal growth by absorbing moisture. 3.9.23 Microbial Nutrients. Since fungi, bacteria, and other microorganisms are classified as living, it was previously thought that only materials derived from living organisms could provide them with food. Thus wool, cotton, feathers, leather, etc., were known to be microbial nutrients. To a large extent this rule of thumb is still valid, but the increasing complexity of synthetic materials makes it difficult, if not impossible, to determine from the name alone whether a material will support growth of microorganisms. Many otherwise resistant synthetic materials are rendered susceptible to microbial attack by the addition of chemicals, which change the properties of the material. In addition, different species of microorganisms have different growth requirements. The service life, size, shape, surface smoothness, cleanliness, environment, and species of microorganism involved all determine the degree of microbial attack on the affected item. 3.10 DEGRADATION OF NON-METALS. Non-metallic materials (plastics, elastomers, paints, and adhesives) are not subject to electrochemical corrosion, since ions are not easily formed from non-metallic materials and their electrical conductivity is extremely low. The degradation of non-metals depends on the chemical makeup of the material and the nature of the environment. In general, non-metallic materials on C-E-M and related equipment are selected for their obvious performance properties (flexibility, transparency, strength, electrical resistance, etc.) as well as their resistance to heat, impact, abrasion, ultraviolet radiation, moisture, ozone and other detrimental gases, and operational fluids such as hydraulic fluid, lube oil, cleaners, deicing fluids, etc. However, the use of unauthorized maintenance chemicals and procedures can accelerate degradation and ultimately lead to material failure resulting in leakage, corrosion, electrical shorts, crazing, and/or mechanical failure. 3-19
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TO 1-1-700 TECHNICAL MANUAL CORROSI
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TO 1-1-700 TABLE OF CONTENTS Chapte
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TO 1-1-700 TABLE OF CONTENTS - CONT
Page 7 and 8: TO 1-1-700 TABLE OF CONTENTS - CONT
Page 13 and 14: TO 1-1-700 LIST OF ILLUSTRATIONS -
Page 15 and 16: TO 1-1-700 FOREWORD 1. PURPOSE. The
Page 17 and 18: TO 1-1-700 List of Related Publicat
Page 19 and 20: TO 1-1-700 SAFETY SUMMARY 1. GENERA
Page 21 and 22: TO 1-1-700 AMS-G-6032, GREASE, PLUG
Page 23 and 24: TO 1-1-700 MIL-DTL-64159, COATING,
Page 25 and 26: TO 1-1-700 MIL-PRF-27617, GREASE, A
Page 27 and 28: TO 1-1-700 O-L-164, DRESSING, LEATH
Page 29: TO 1-1-700 MIL-T-81772, THINNER, PO
Page 32 and 33: TO 1-1-700 tronics equipment and th
Page 34 and 35: TO 1-1-700 cleaning situation, syst
Page 36 and 37: TO 1-1-700 c. Riveted joints shall
Page 38 and 39: TO 1-1-700 c. Remove and replace an
Page 40 and 41: TO 1-1-700 MIL-L-87177, LUBRICANT,
Page 42 and 43: TO 1-1-700 Figure 3-1. Simplified C
Page 44 and 45: TO 1-1-700 resistant, and also at t
Page 46 and 47: TO 1-1-700 is first noticeable as a
Page 48 and 49: TO 1-1-700 3.7.8 Oxygen Concentrati
Page 50 and 51: TO 1-1-700 Figure 3-14. Concentrati
Page 52 and 53: TO 1-1-700 Figure 3-17. Galvanic Se
Page 54 and 55: TO 1-1-700 Figure 3-20. Aluminum Su
Page 56 and 57: TO 1-1-700 3.8.7 CRES/Stainless Ste
Page 60 and 61: TO 1-1-700 3.11 PREVENTATIVE MAINTE
Page 63 and 64: TO 1-1-700 CHAPTER 4 COMPOSITE AND
Page 65 and 66: TO 1-1-700 4.4.4.4 Glass parts shal
Page 67 and 68: TO 1-1-700 CHAPTER 5 PACKAGING (STO
Page 69 and 70: TO 1-1-700 extent of damage dependi
Page 71 and 72: TO 1-1-700 5.15 PRECAUTIONS FOR VCI
Page 73 and 74: TO 1-1-700 c. Secure the desiccant
Page 75 and 76: TO 1-1-700 Figure 5-8. Shock Isolat
Page 77 and 78: TO 1-1-700 Figure 5-9. Examples of
Page 79 and 80: TO 1-1-700 5.24.10 Rigid or Flexibl
Page 81 and 82: TO 1-1-700 CHAPTER 6 MOISTURE AND F
Page 83 and 84: TO 1-1-700 c. 6.2.6 Felt. Examine f
Page 85 and 86: TO 1-1-700 a. After first directing
Page 87: TO 1-1-700 6.4.5.14 Terminals, scre
Page 90 and 91: TO 1-1-700 NOTE • Authorized clea
Page 92 and 93: TO 1-1-700 Table 7-1. Cleaning of S
Page 102 and 103: TO 1-1-700 7.3.1.2.3 Portable, 45 g
Page 104 and 105: TO 1-1-700 Table 7-2. Common Milita
Page 106 and 107: TO 1-1-700 inactivity, storage, or
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TO 1-1-700 7.5.6.5.1 Grade 1 - A th
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TO 1-1-700 Table 7-4. Corrosion Pre
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TO 1-1-700 Table 7-5. Preservation
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TO 1-1-700 either case, MIL-PRF-269
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TO 1-1-700 MIL-PRF-85285, COATING,
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TO 1-1-700 c. Cadmium plated surfac
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TO 1-1-700 a. Scuff sand and feathe
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TO 1-1-700 7.7.7.2 If surface is no
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TO 1-1-700 7.7.9.2 Where only parti
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TO 1-1-700 7.8.1 Type I Application
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TO 1-1-700 Extend (Loctite) 32150 J
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TO 1-1-700 There are three ways to
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TO 1-1-700 vulnerable surfaces clea
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TO 1-1-700 Table 8-2. Materials, Th
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TO 1-1-700 Table 8-4. Electronic Cl
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TO 1-1-700 Table 8-5. Accessories o
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TO 1-1-700 Table 8-5. Accessories o
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TO 1-1-700 f. Devices with permanen
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TO 1-1-700 Table 8-7. Cleaning and
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TO 1-1-700 MIL-PRF-87937, CLEANING
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TO 1-1-700 of contamination). Maint
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TO 1-1-700 8.8.2 Protective Coating
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TO 1-1-700 • Tube clamps. • Min
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TO 1-1-700 a. For bonding/grounding
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TO 1-1-700 vertently destroy the mo
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TO 1-1-700 doors, and other corrosi
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TO 1-1-700 CHAPTER 10 CORROSION PRO
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TO 1-1-700 MIL-PRF-81733, SEALING A
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TO 1-1-700 d. After corrosion is re
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TO 1-1-700 (3) Stainless/CRES steel
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TO 1-1-700 10.9 WATER ENTRAPMENT AR
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TO 1-1-700 f. Shield equipment from
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TO 1-1-700 b. Use e-inch rivnuts of
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TO 1-1-700 10.17.3 If the plating s
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TO 1-1-700 Figure 10-16. Dissipatio
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TO 1-1-700 (2) If allowable damage
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TO 1-1-700 Table 11-1. Recommended
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TO 1-1-700 11.6 3M CO. SCOTCH-BRITE
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TO 1-1-700 11.11.2 Control of Mecha
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TO 1-1-700 11.12.2 Mechanical Damag
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TO 1-1-700 MIL-DTL-81706 (ALODINE),
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TO 1-1-700 11.13.2.3 Application of
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TO 1-1-700 only when there is no da
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TO 1-1-700 NOTE SEMCO PASA-JELL 101
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TO 1-1-700 (CRES), lead, ceramic, g
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TO 1-1-700 11.13.7.2 Treatment of C
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TO 1-1-700 MIL-A-46106, ADHESIVE/SE
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TO 1-1-700 Table 12-1. Sealing Comp
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TO 1-1-700 used to apply sealants i
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TO 1-1-700 Figure 12-2. Sealant App
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TO 1-1-700 Figure 12-4. Rivet Appli
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TO 1-1-700 Figure 12-6. Sealant Inj
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TO 1-1-700 below and adhere very po
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TO 1-1-700 Table 12-2. Time Require
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TO 1-1-700 Table 12-2. Time Require
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TO 1-1-700 of 20 to 25 seconds in a
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TO 1-1-700 d. Remove all uncured se
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TO 1-1-700 Figure 12-12. Typical Me
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TO 1-1-700 may be used for low temp
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TO 1-1-700 Figure 12-14. Sealing Pr
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TO 1-1-700 - Robins Air Force Base

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