Page 73 - 20250602 EEA QM Edition 6.0

Quality Requirements Edition 6.0 European Enamel Association

B. Enamelling

Test method Requirement Remarks Frequency
3.5 visual assessment external: fundamental defects may not occur fundamental defects are flake off, chip off, 100 %
internal: in consultation copper heads, fish scales, pull off, burning
through as described in NEN 2711
4.3 thickness enamel coating 120 - 400μm 2 % in production

4.9 impact resistance at 20 N no damages > 2.0 mm diameter after 24 hours on test sheets, conform to EN ISO 28764 when taking into production new
recipe, but at least 1 x a year
4.10 adherence min. 2 on test sheets, conform to EN ISO 28764 in production 1 x a day
2
4.13 defects external < 25 / m per individual sheet according to defects in the form of cracks are not permitted 2 %
method B; average < 10 / m with respect to sheets
2
forming part of a heat exchanger bloc. Internal method
and quality requirement to be discussed in consultation
with principal and enameller, depending on application
flatness requirement after the enamelling if required in consultation between if required in consultation between
enameller and customer enameller and customer
4.35 boiling sulphuric acid max. 3.0 g/m Test specimens shall be prepared in 1 x per 10 tons enamel
2
accordance with EN ISO 28764 and shall be
pre-treated and enamelled under the same
circumstances as the production of the heat
exchanger parts. They shall have an enamel
layer of 150μm ± 20μm.
4.40 thermal shock resistance 5 x 350 °C on test sheets conform to EN ISO 2723 when taking into production new
enamel recipe, but at least 1 x a year
the resistance is tested on sheets of 100 mm
x 100 mm with an enamel coating thickness
of 150μm ± 20μm.
The sheets are cooled down in water at 20°C

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