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Tender Specification coil coating Coil requirements Polyurethane coating impregnated with metallic pigment to prevent loss of heat conductivity.
Coil / heat exchanger fins shall be of an aluminum and/or copper construction with a protective coating applied after construction of the coil to achieve a total coverage. The coating shall not block the possible fin perforations. Coating shall be repairable and maintainable on site.
Coating characteristics:
Coating shall be UV resistant, flexible, heat conductive, chemical resistant to most (aggressive) environments. A resistance list must be available
Application:
Due to the specialized nature of the corrosion protection system, it is essential that only a qualified applicator is contracted for this application. The entire unit shall be prepared in order to obtain access to the finned coils. Wiring and sensitive electrical components shall be protected during the cleaning and coating process. The most critical areas which have to be coated are the heat exchangers surfaces (finned coils). Protection against corrosion shall be achieved by means of a high pressure spray technique that ensures full penetration but prevents bridging (thus preventing capacity loss).
Copper elbows (returns), headers and brazing parts are pretreated with special Polyurethane primer to ensure maximal adhesion and protection to these areas.
Quality level
Quality level of the treatment should meet the following requirements.
The penetration of the coil has to be 100%, to be established and proven by the working method and visual inspection.
The adhesion level should meet Cross hatch test level 0 (European) and
5B (USA) according to ASTM 3359-83 53151 method B-A
The thickness level should meet 1 mil (25 µm) plus or minus 20 %.
ASTM-B117 (DIN 53167) 4000 hours
Conditions:
ASTM-B287 (DIN 50021) 4000 hours
Conditions :
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