TT-C-490F
be in accordance with SSPC-VIS 3, with any of the appropriate SSPC cleaning standards to achieve visual cleanliness condition A, SP3/SD minimum unless otherwise specified by drawing or design engineering. Use the visual standards for cleanliness for steel as a guide for other metal substrates as well. Water break testing for surface cleanliness shall precede and follow mechanical or abrasive blast cleaning to ensure that the cleaning tools or media do not become contaminated and the substrate is meticulously clean.
3.3.3.2 Method II - solvent cleaning by immersion, spray, vapor, or hand wiping. Solvent cleaning often leaves a hydrophobic surface even though organic soils have been removed. This method may not be the best choice. Failure of the water break test shall require the use of one or more of the other Methods cited. Do not use solvents that would damage any existing coatings, sealants, adhesives or other
materials that are to remain in place. The wipers or cloths used and the cleaning solvent shall be kept clean so as not to spread the contaminant over the substrate. Do not use halide solvents to clean titanium, magnesium or aluminum. Unless in a vapor controlled system whereby the solvent is distilled and
reused, cleaning with solvent shall not be the first choice for cleaning. Substrates that are solvent cleaned shall pass the water break test as described in 4.7.3.1.
3.3.3.3 Method III - detergent cleaning by immersion, spray or electrolytic methods. Detergent cleaning shall be used to remove unwanted substances, contamination and soils. Do not use detergents that are so aggressive as to damage the metal substrate or any coatings or other materials that are to remain in
place. Use guidance that is supplied by the detergent supplier's technical data sheet to avoid excessive etching or other deleterious effects. Substrates that are detergent cleaned shall pass the water break test as described in 4.7.3.1.
3.3.3.4 Method IV- emulsion cleaning. With this method of cleaning three distinct steps shall be performed. Step 1 is pre-cleaning whereby the heavy soils are removed using the cleaning solutions either by immersion or delivered with pressurized nozzles. This pre-cleaning keeps the heavy soils from fouling the secondary cleaning system. Step 2 is a secondary cleaning cycle utilizing the same or similar cleaning solutions delivered by an array of pressurized nozzles to remove the soils. Step 3 is a rinse
cycle utilizing clean water to thoroughly rinse the cleaning solution from the parts. Use the same controls to check visual cleanliness and water break as described in 4.7.3.1. Do not use cleaning materials or temperatures that could cause damage to any coated surface that is to remain in place or to the metallic substrate. Use guidance provided by the chemical supplier's technical data sheet to avoid etching or other deleterious effects. Substrates that are emulsion cleaned shall pass the water break test as described in 4.7.3.1.
3.3.3.5 Method V - derusting/deoxidizing by chemical means. Deoxidize or derust metals by chemical means or enhance the process by using electrolytic systems for faster removal. Extreme caution shall be exercised to avoid excessive material removal especially on critical surfaces with close tolerances and materials subject to hydrogen embrittlement. Ferrous materials, harder than HRC 39, shall not be chemically etched or derusted unless the materials used and the process has been preapproved (see
3.2.7). Substrates that are derusted/deoxidized by chemical means shall pass the water break test as described in 4.7.3.1.
3.3.3.6 Method VI - phosphoric acid cleaning (detergent or solvent type with detergent). Ferrous materials, harder than HRC 39, shall not be cleaned or derusted with phosphoric acid containing compounds unless the materials and process used has been pre-approved. Substrates that are phosphoric acid cleaned shall pass the water break test as described in 4.7.3.1.
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