AC 43-206

Change 1

Advisory circular · Inspection, Prevention, Control, and Repair of Corrosion on Avionics Equipment

Approved
August 7, 2024
Last reviewed
August 12, 2024
This change
CHG 1 of AC 43-206.
Cancels
AC43-206
Family
AC 43-206 · 2 versions
Revision
change 1
14 CFR parts
43
Cited by
2 ADs

Guidance, not mandatory unless a rule or AD requires it. DRS record last changed November 21, 2025.

Show pages 193–204
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Appendix 1 ITEM NO.

NOMENCLATURE/PRODUCT

SPECIFICATION

APPLICATION

CLEANING COMPOUNDS, SOLVENTS, AND THINNERS CAUTION: Cleaning solvents may react with coatings and circuit components. When in doubt as to the reaction, test the affected area prior to wholesale application of solvent.

NOTE: Local air pollution regulations may restrict the use of the listed solvents. Comply with all local air pollution regulations.

8. Detergent, Liquid Nonionic, MIL-D-16791, Type I For cleaning and polishing transparent plastic and glass.

Note: Mix per manufacturer’s instructions or not more than 1 oz. per gal. of water. Also used for detergent in aqueous ultrasonic cleaners and aqueous spray cleaning booths.

9. Cleaning Compound, MIL-PRF-85570, Type II General cleaning. For removal of soil and fire extinguishing chemicals. Excellent cleaner for light oils and hydraulic fluids.

10. Cleaning Compound, Solvent, Trichlorotrifluoroethane, MIL-C-81302, Type II For use only in vapor degreasers.

11. Cleaning Compound, Solvent Trichlorotrifluoroethane, MIL-C-81302, Type I (Ultra-clean) For use only in vapor degreasers.

12. Dry Cleaning Solvent, MIL-PRF-680, Type II For general purpose cleaning of structural hardware, cases, covers, mountings, etc. For removal of heavy dirt, smoke damage, contaminants, fire extinguishing chemicals, and water-displacing preservatives.

WARNING: MIL-PRF-680, Type I has a lower flash point of 100 °F (38 °C) and is not authorized for avionics cleaning.

13. Naphtha, Aliphatic, TT-N-95B, Type II For removal of polychlorinated biphenyl and silicone contaminants.

WARNING: Aliphatic Naphtha has a flash point of

60.8 °F (16 °C).

14. Isopropyl Alcohol, TT-I-735 For removal of fungus and bacteria. For removal of Van Waters and solder flux residue. For removal of contaminants on microminiature circuit components.

For general cleaning and removal of salt residue and contaminants from circuit components.

WARNING: Isopropyl Alcohol has a flash point of 53 °F (12 °C).

15. Spray Cleaning Lubricating Compound, MIL-PRF-29608, Type I Cleaner and lubricant for use on small switches and potentiometers where a residual lubricant is required after cleaning. Contains 5% silicone.

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Appendix 1 ITEM NO.

NOMENCLATURE/PRODUCT

SPECIFICATION

APPLICATION

16. Thinner, Acrylic Nitrocellulose Lacquer, MIL-T-19544 Thinner for Lacquer, Acrylic Nitrocellulose MIL-L-19538C, MIL-C-22750, epoxy topcoats, Item No. 59 and 60, and MIL-P-23377 primer, Item No. 58.

17. Thinner, Paint, Petroleum Spirits TT-T-291, Type III Removal of preservative compounds.

CAUTION: Do not use on lacquers or synthetic resin base enamels.

18. Thinner, Synthetic Resin, Enamels A-A-3007 Used for thinning varnish, MIL-V-173C, Item No. 51.

CAUTION: Do not use in lacquers.

19. Thinner, Aliphatic Polyurethane Coating, MIL-T-81772, Type I (Polyurethane) Type II (Epoxy) Type III (Lacquer) For thinning urethane and polyurethane topcoats, MIL-C-83286B, and MIL-PRF-85285, Item No. 61 and 63; epoxy polyamide coatings, MIL-C-22750, Item No. 60; acrylic nitrocellulose lacquers, MIL-L-19538C, Item No. 59; and primer, MIL-P-23377, Item No. 58.

CORROSION PREVENTIVE COMPOUNDS (PRESERVATIVE)

WARNING: Do not use Corrosion Preventive Compounds around oxygen, oxygen fittings, or oxygen regulators, since fire or explosion may result.

20. Corrosion Preventive Compound, Water-Displacing, Ultra-Thin Film, Avionics Grade, MIL-PRF-81309, Type III, Class 2 (Aerosol) For use on highly critical electrical connectors’ metal surfaces. For use in interior areas. Not intended for exterior areas exposed to the elements.

21. Corrosion Preventive Compound, Water-Displacing, Ultra-Thin Film, MIL-PRF-81309, Type II, Class 2 (Aerosol), Class 1 (Bulk) For use on all exposed metal and hardware on external chassis, covers, etc. Not intended for exterior areas exposed to the elements.

22. Corrosion Preventive Compound, Water-Displacing, Clear, MIL-DTL-85054, Type I (Aerosol) Water-displacing corrosion preventive. For use on all external surfaces exposed to elements and moisture. For use on chassis, mounting racks, terminal boards, hardware, bus bars, ground straps, etc.

23. Corrosion Preventive Compound, Solvent Cutback, Cold Application MIL-PRF-16173, Grade 4 (Transparent Film) For use on equipment racks, mounts, exposed hardware, etc. For use on exterior surfaces of electrical plugs and connectors. Not intended as a water-displacing compound.

LUBRICATING OILS AND GREASES

24. Lubricating Oil, General Purpose, Preservative (Water-Displacing), MIL-PRF-32033 General lubricating and protection of avionics components, hinges, and quick release devices. Suitable for use where a general purpose lubricating oil with low temperature and corrosion preventive properties is desired.

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Appendix 1

25. Grease, Instrument, Ultra-clean, MIL-G-81937 For lubrication of bearings in instruments and related components such as synchros and gyros. Ideally suited for bearings having small tolerances with respect to clearance.

26. Lubricating Oil Instrument, Ball Bearing, High Flash Point, MIL-L-81846 For use in precision instruments and miniature ball bearings. Temperature range of -65 °F (-54 °C) to 302 °F (150 °C).

27. Grease, Aircraft, General Purpose, Wide Temperature Range, MIL-G-81322 For use on blower motors, servomotors, and gyro spin motors.

28. Lubricating Solid Film, Air-Cured, Corrosion Inhibiting, MIL-L-23398 For use on aluminum alloys, copper and copper alloys, steel, stainless steel, titanium, and chromium and nickel bearing surfaces. For use on sliding motion applications such as locks, small internal cables, plain and spherical bearings, tracks, hinges, threads, and cam surfaces. For use in mechanisms that are lubricated for life, and in mechanisms operated at infrequent intervals.

CAUTION: Not to be used in operations consisting of rotary motion over 100 revolutions per minute (rpm) under heavy loads where the possibility of conventional fluid lubricant contamination exists.

Not to be used on bearings containing rolling elements.

CLEANING CLOTH

29. Cloth, Cleaning, Non-Woven Fabric, CCC-C-46, Class 7 No lint, extra heavy duty, moderate wet strength, good absorbency, and disposable. For use when good wet strength and short term rewetting is required, and for wiping critical avionics equipment.

WARNING: Not approved for use in wiping plastic and acrylic surfaces with solvents having a flash point of less than 100 °F (38 °C).

30. Cloth, Cleaning, Lint-Free, MIL-C-85043, Type I or Type II Very low lint, relatively low absorbency, good wet strength, intended for wash and reuse. For use on critical surfaces where low contamination levels are required. Type I preferred for clean room applications.

CAUTION: Not authorized for use with solvents having a flash point of less than 100 °F (38 °C).

31. Cloth, Cheesecloth, Cotton, CCC-C-440, Type II, (28 x 24 weave), Class 1, Unbleached, or Class 2, Bleached Moderate lint, high absorbency, high wet strength, reusable after washing, and disposable. For general cleaning on exterior surfaces of avionics equipment.

For use as a tack rag and final wipe prior to painting.

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Appendix 1

32. Cotton, Flannel, CCC-C-458, Type II (plain weave, unbleached, napped both sides, 4.6 oz. weight) High lint, high absorbency, high wet strength, reusable after washing, and disposable. For use on cockpit indicator glass covers, plastic and acrylic control panels.

NOTE: Only authorized cloth for use in cleaning plastic and acrylics with solvents that have a flash point of less than 100 °F (38 °C).

SEALANTS

33. Adhesive-Sealant Silicone, Room Temperature Vulcanizing (RTV), Noncorrosive, 3145 RTV, MIL-A-46146, Type III For use on sensitive metals and avionics equipment.

Sealing areas where temperature is expected to be between 250 °F (121 °C) and 350 °F (177 °C).

34. Sealing Compound, Polysulfide, MIL-PRF-81733, Type I (Brush Application), Type II (Spatula Application) Contains corrosion inhibitors. For use in sealing gaps, seams, etc. For use up to 250 °F (121 °C).

35. Sealing Compound, SAE-AMS-S-83318 A quick-cure sealant that contains corrosion inhibitors.

For use in sealing gaps, seams, etc., during extreme cold weather activities.

36. Sealing Compound, Temperature-Resistant, Integral Fuel Tanks, SAE-AMS-S-8802, Type A, Class 2 (Brush Application) or Type B, Class 2 (Spatula Application) Sealing of gaps, seams, and faying surfaces. For use up to 250 °F (121 °C). Use when MIL-PRF-81733 is not available.

POTTING COMPOUNDS CAUTION: Potting Compounds Pro-Seal 777A/B (green) and EC-2273 (black) have experienced reversion to a liquid after 2 to 4 years of service depending on the environment. Not recommended for use in electrical connectors and avionics equipment.

37. Sealing Compound, Synthetic Rubber, Accelerated, MIL-PRF-8516 Class 1 (24 hr. cure) or Class 2 (48 hr. cure) or Class 3 (72 hr. cure) For sealing low voltage electrical connectors, wiring, and other electrical apparatus against moisture and corrosion where temperature will not exceed 200 °F (93 °C). Good resistance to gasoline, oils, grease, water, and humidity.

CAUTION: Not authorized for use in engine bays, keel areas, or areas adjacent to bleed air ducts.

38. Sealing Compound, Silicone Rubber, Room Temperature RTV, MIL-S-23586, Type II, Class 2, Grade A For sealing small electrical connectors in well-ventilated areas where the operating temperature normally exceeds 200 °F (93 °C), but does not exceed 450 °F (232 °C). Good resistance to weathering and moisture, and withstands ozone.

CAUTION: Restricted to well-ventilated areas due to volatile cure.

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Appendix 1

39. Sealing Compound, Silicone Rubber, RTV, MIL-S-23586, Type I, Class 1, Grade B-1 For sealing or encasement of electrical connectors and electronic components where the operating temperature normally exceeds 200 °F (93 °C), but does not exceed 450 °F (232 °C). Good resistance to weathering and moisture, and withstands ozone.

NOTE: Does not contain cure volatiles as MIL-S-23586, Type II, Class 2, Grade A.

MASKING MATERIALS AND TAPES

40. Preservation and Sealing Tape, Pressure Sensitive Adhesive, MIL-T-22085, Type II For holding barrier material in place during shipping.

Treated, noncorrosive, non-fungus supporting. For use on equipment without overcoating.

41. Tape, Pressure Sensitive Adhesive, Paper Masking, Non-staining, MIL-T-21595, Type I For masking of undamaged areas during paint touch-up on equipment cases, covers, mounting racks, etc. For masking electrical and electronic components during replacement of conformal coatings and varnishing.

CAUTION: Use only if component is sufficiently rigid to withstand application and removal of tape.

42. Tape, Pressure Sensitive Adhesive, MIL-T-23397, Type II For masking during paint stripping operations on avionics equipment and airframe structure.

43. Tape, Pressure Sensitive, MIL-T-23142 For isolating dissimilar metals where galvanic action may take place in avionics equipment.

44. Insulating Tape Electrical, Self Bonding, Silicone Used to wrap electrical wire bundles and connectors exposed to harsh environments.

45. Paper, Kraft, Untreated, Wrapping, UU-P-268 Protection of surrounding areas during paint spray operations. General-use masking.

CONFORMAL COATINGS NOTE: Materials listed are for general purpose use on conformal coated circuit boards. For special applications on highly critical components, refer to the OEM’s maintenance manual.

46. Epoxy Coating, Two-Part Application For coating and patching epoxy- and parylene-coated circuit boards and components.

47. Polyurethane Coating (Brush Application) For coating and patching polyurethane and varnish coated circuit boards and components.

48. RTV Coating, Nonflowable (Brush Application), 738 RTV (White) MIL-A-46146, Type I For coating and patching RTV coated circuit boards and components.

NOTE: Will not flow into crevices or other hard to reach places.

49. RTV Coating, Flowable (Brush Application), 3140 RTV (Clear) MIL-A-46146, Type III For coating and patching RTV coated circuit boards and components.

NOTE: Use in applications where a flowable material is required, such as potting connectors.

50. Acrylic Coating For coating and patching of acrylic and lacquer coated circuit boards and components.

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Appendix 1

51. Varnish, MIL-V-173C Moisture and fungus resistant for electrical equipment and for clear coating on copper. For coating and patching of varnish coated circuit boards.

NOTE: Thinner: see Item No. 18.

NEUTRALIZING AGENTS

52. Sodium Bicarbonate, Technical, O-S-576 For neutralizing spilled sulfuric acid (electrolyte) in lead acid battery installations. For neutralizing leaking tantalum capacitors in avionics equipment.

53. Sodium Phosphate, Monobasic, Anhydrous, Technical, AWWA B504-18 For neutralizing spilled potassium hydroxide (electrolyte) in nickel-cadmium and silver-zinc battery installations. Also used as an abrasive material in miniabrasive cleaning units.

CHEMICAL CONVERSION COATINGS

54. Boric Acid, A-A-59282 For neutralizing electrolyte leakage from nickel-cadmium batteries.

55. Chemical Conversion Material for Coating Aluminum and Aluminum Alloys, MIL-DTL-81706, Class 1A or Class 3 Used to conversion coat bare aluminum. Class 1: used for general conversion coating of aluminum. Class 3:

used for conversion coating of aluminum where lower electrical resistance is required.

56. Chemical Conversion Material for Coating Magnesium Alloys, SAE-AMS-M-3171, Type VI Used to conversion coat bare magnesium.

PAINT, PRIMERS, AND STRIPPERS

57. Epoxy Primer, Water Reducible, MIL-P-85582, Class II, Class I Covers low-moisture sensitivity, corrosion-inhibited primer. Intended for spray application on surface treated metal. Low Volatile Organic Compound (VOC).

58. Primer Coating, Epoxy Polyamide, MIL-P-23377, Type II Covers low-moisture sensitivity, corrosion-inhibited primer. Intended for spray application on surface treated metal.

59. Lacquer, Acrylic Nitrocellulose, MIL-L-19538C (Lusterless) Used for cockpit instrument, control box, and avionics box touch-up. For equipment markings.

60. Coating, Epoxy-Polyamide, MIL-C-22750 Used as a topcoat on all avionics equipment.

NOTE: Mix only materials from the same kit (the brand and batch numbers on the pigmented compound can must be the same as those on the converter can).

61. Coating, Urethane, Aliphatic, Isocyanate, MIL-C-83286B Used as a topcoat on all avionics equipment. Touch-up of polyurethane paint systems. (Noncompliant.)

62. Coating, Aliphatic Polyurethane, Single Component, MIL-C-53039 Used as a topcoat on all avionics equipment.

63. Coating, Polyurethane High Solids, MIL-PRF-85285, Type I and Type II Type I used as a topcoat on all avionics equipment.

420 grams/liter maximum VOC.

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Appendix 1 Type II used as a preferred topcoat for ground support equipment. 340 grams/liter maximum VOC.

64. Coating Compound, Bituminous Solvent Type, Black, MIL-C-450, Low Solids Spraying Consistency or Medium Solids Brush and Spray Consistency Petroleum asphalt base. Excellent acid resistance. For use on wood or metal battery boxes. Drying time: 30 to 60 minutes.

NOTE: Thinner: Petroleum Spirits, TT-T-291, Item No. 18.

65. Epoxy Paint Remover, QPL-81294 Removal of paint finishes.

66. Polyethylene Foam, PPP-C-1752, Type II 1/2" x 4' x 125', in rolls For cushioning equipment and protection against shock, on shelves, work benches, pallets, etc.

NOTE: Use double layers for heavy equipment.

PACKAGING MATERIALS

67. Cushioning Material, Plastic Open Cell, PPP-C-1842, Type III, Style A;

Type III, Style B;

Width 12", 24", and 48" in rolls To protect ESD-sensitive items from damage due to shock, vibration, corrosion, and abrasion during handling and shipment.

68. Cushioning Material, Cellular Plastic Film (Bubble Wrap), PPP-C-795, Class 1 or Class 3 Width 12", 24", and 48" in rolls For cushioning equipment and protection against shock.

Provides limited protection against moisture. Seal with pressure-sensitive tape, MIL-T-22085, Item No. 40.

69. Unicellular Polypropylene Packaging Foam, PPP-C-1797 Width 12", 24", and 48" in rolls Lint-free, non-dusting, nonabrasive. For cushioning equipment and protection against shock. Provides protection against moisture. Use in conjunction with Barrier Material, Water Vapor Proof, MIL-B-131, Item No. 72. Seal with pressure-sensitive tape, MIL-T-22085, Item No. 40.

70. Bags, Plastic (General Purpose), PPP-B-26 For protecting miniature and microminiature circuit components and laminated circuit boards against moisture and contamination. Considered for short-term, temporary protection during maintenance operation.

71. Barrier Material, Water Vapor proof, Greaseproof, Flexible, Heat-Sealable, MIL-B-131, Class 1, 48" x 200 yd. roll For protecting miniature and microminiature circuit components and laminated circuit boards against moisture and contamination. Heat-sealable. Protects material during transportation, storage, and in all weather conditions.

72. Barrier Material, Water Vapor proof, Protective, Electrostatic and Electromagnetic Shielding, MIL-B-81705, Type I Provides ESD and electromagnetic interference (EMI) packaging protection for hardware and components.

May be used for long or short-term protection. Can be heat-sealed.

73. Barrier Material, Water Vapor proof, Protective, Electrostatic and Electromagnetic Static Dissipative, MIL-B-81705, Type II Provides ESD and EMI packaging protection for hardware and components. May be used for long or short-term protection. Can be heat-sealed.

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Appendix 1

TRACERS

74. Indicator, Thymol Blue Reagent, MIL-T-17412 For detecting reverse voltage damage to wet-slug tantalum capacitors. Also used as a Nicad electrolyte indicator.

75. Desiccant, Bagged, MIL-D-3464, Grade A Absorbs moisture, lowers relative humidity when sealed in container.

76. Humidity Indicator, MS-20003 Used to determine that desiccant within a package is sufficiently active to maintain a relative humidity below that at which corrosion will occur.

77. Water, Distilled Used for cleaning in critical soldering operations.

78. Ammonium Hydroxide, Technical, O-A-451 Used to assist in dissolving indicator, Thymol Blue Reagent, A-A-59282.

79. Glass Beads, MIL-G-9954 Used as abrasive in handheld tool in blast cleaning cabinet.

80. Silver Nitrate, A-A-59282 Used to identify magnesium metal.

81. Silver Nitrate, Solution, MIL-W-535 Used to identify magnesium metal.

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Appendix 2 APPENDIX 2. SPECIFIC CONSUMABLE MATERIALS FOR CLEANING AND

CORROSION PREVENTION AND CONTROL

2-1. INTRODUCTION AND SCOPE.

This appendix supplements Appendix 1 by providing a more detailed listing of selected products by product numbers (P/N) and manufacturer(s) of acceptable consumable materials for avionics cleaning and corrosion prevention and control. Table 2-1 provides product numbers and manufacturer’s name. Table 2-2 provides a listing of the manufacturers and addresses of their main plants.

Table Grouping Page(s) 2-1 Cleaning Compounds…………………………………………1 Corrosion Preventive Compounds………………………….1-2 Sealants……………………………………………………..2-3 2-1 2-1 TABLE 2-1. AVIONICS CLEANING AND CORROSION REMOVAL CONSUMABLE

MATERIALS ITEM NO. PRODUCT TYPE MANUFACTURER’S

DESIGNATION CLEANING COMPOUND, MIL-PRF-85570 9 Type II Leeder 1140-F 9 Type II 8505 9 Type II Calla 855 9 Type II Aerowash NV 9 Type II AC-17 8 9 Type II ED-4 10 9 Type II EZE-445 9 Type II MA-102 9 Type II CeeBee R-682 9 Type II 8002-2-SD 9 Type II Octagon 855702 9 Type II LD-38 9 Type II PENN AIR M5572B 9 Type II 93-1 9 Type II Turco 6692 CORROSION PREVENTIVE COMPOUND, MIL-PRF-81309, Class 1 (Bulk), Class 2 (Aerosol) 20 Type III 2080-MLCO 20 Type III So-Sure 0964-000 20 Type III LPS-814A 20 Type III 22028C2-3 20 Type III Ardrox 3205 Aerosol

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Appendix 2 ITEM NO. PRODUCT TYPE MANUFACTURER’S

DESIGNATION 20 Type III CRC 3-36 20 Type III ACF-50 Aerosol 21 Type II Class 1 Alox 2028C 21 Type II Class 1 Aidchim Alox 2080 21 Type II Class 1 2028 BC-BULK 21 Type II Class 1 Nox Rust 212 21 Type II Class 1 2775 21 Type II Class 1 So-Sure 813 21 Type II Class 1 LPS-813 Bulk 21 Type II Class 1 Octoil 5068 21 Type II Class 1 Omni 4150A 21 Type II Class 1 97-SX092 21 Type II Class 1 22018CM-Bulk 21 Type II Class 1 Ardrox 3204 21 Type II Class 1 BATCO Rust Preventive 21 Type II Class 1 706 P.D.R.P. Bulk 21 Type II Class 1 D-5026 Bulk 21 Type II Class 1 Ardrox 3204 Aerosol 21 Type II Class 2 2028-BCCO Bulk 21 Type II Class 2 So-Sure 0954-000 21 Type II Class 2 LPS-813A 21 Type II Class 2 706 P.D.R.P 21 Type II Class 2 22028C2 CORROSION PREVENTIVE COMPOUND, MIL-PRF-16173 23 Grade 4 TECTYL 846 23 Grade 4 846-BC 23 Grade 4 Braycote 194 23 Grade 4 CONVOY 734 23 Grade 4 Nox-Rust X-110 23 Grade 4 F & L 5846 23 Grade 4 Steelgard MS-31 23 Grade 4 Poly Oleum 5000 23 Grade 4 ST 1846 23 Grade 4 No-Rust X-10 SEALANTS MIL-PRF-81733, Type I (Brush Application), Type II (Spatula Application) NOTE: Dash number following Type gives working time of the sealant in hours.

34 Type I-1/2 P/S 870 A-1/2 34 Type I-1/2 PR 1440G A-1/2 34 Type I-2 P/S 870 A-2 34 Type I-2 PR 1440G A-2 34 Type II-1/2 P/S 870 B-1/2 34 Type II-1/2 PR 1440G B-1/2

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Appendix 2 ITEM NO. PRODUCT TYPE MANUFACTURER’S

DESIGNATION 34 Type II-2 P/S 870 B-2 34 Type II-2 PR 1440G B-2 34 Type II-2 PR 1436G B-2 34 Type II-4 P/S 870 B-4 34 Type II-4 PR 1440G B-4 SEALANTS SAE-AMS-S-8802, Class A (Brush Application), Class B (Spatula Application) NOTE: Dash number following Class gives working time of the sealant in hours.

36 Class A-1/2 PR-1422 36 Class A-2 36 Class B-1/2 36 Class B-1 36 Class B-2 36 Class B-2 BR 4005 36 Class B-1/2 FR 1072 36 Class B-2 36 Class A-1/2 CS-3204 36 Class A-1 36 Class A-2 36 Class B-1/2 36 Class B-1 36 Class B-2 36 Class B-1 WS-8020 36 Class B-2 36 Class B-4 36 Class B-1/2 MC-236 36 Class B-1 36 Class B-2 36 Class B-2 PR-1440 36 Class A-1/2 PR-1440 36 Class A-1 PR-1440 36 Class A-2 Pro-Seal 890 36 Class A-2 PR-1440 36 Class B-1/2 Pro-Seal 890 36 Class B-1/2 PR-1440 36 Class B-1 PR-1440 36 Class B-2 Pro-Seal 890 36 Class B-2 PR-1440 36 Class B-4 Pro-Seal 890 36 Class B-4 PR-1440

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Appendix 3 APPENDIX 3. DEFINITION OF TERMS Acetic Acid An organic acid that can form when a microorganism (acetobacteraceti) reacts with ethyl alcohol in the presence of oxygen. Characteristic of vinegar.

Acidic Acid forming or having acid characteristics.

Active Metal A metal ready to corrode or being corroded.

Additive A compound added for a particular purpose. For example, additives in fuel and lubricants can prevent corrosion, gum formation, varnishing, sludge formation, and knocking.

Aerobic A process which is incapable of occurring in the absence of oxygen.

Alkaline Having a pH greater than 7.

Alloy A combination of two or more metals.

Anaerobic A process which is capable of occurring in the absence of oxygen.

Anion A negatively charged ion of an electrolyte which migrates toward the anode. The chloride in sea water is an anion.

Anode The electrode of a corrosion cell at which oxidation or corrosion occurs. It may be a small area on the surface of a metal or alloy, such as that where a pit develops, or it may be the more active metal in a cell composed of two dissimilar metals, (i.e., the one with the greater tendency to go into solution). The corrosion process involves the change of metal atoms into actions with a liberation of electrons that migrate through the metal to the cathode of the cell.

Anodize Application of a protective oxide film on a metal (such as aluminum) through an electrolytic process. This layer provides protection from corrosion and is a good base for paint.

Aqueous Made from, with, or by water.