Page 68 - QRedition5.0 062021

Quality Requirements Edition 5.0 European Enamel Association

C. Enamelling (cont.)
Test method Requirement Remarks Frequency
3.5 visual assessment fundamental defects may not occur fundamental defects are: blisters, burn-off , 100 %
chipping, copper heads, cracking, crazing,
fish scales, spalling and tearing as
described in EN 14866 part 3 & 6.4.
4.13 open defects maximum number of open defects: defects in form of cracks in a random check op 10 pairs of panels
in accordance with method B air-gas heaters: 50/m 2 are not permitted out of a production of 1000 pair of
2 panels; alternatively the number of
gas-gas heaters: 15/m
defects on pairs of heat exchanger
panels may be determined by checking
1% of production on a 2 hours cycle.
4.20 edge covering for air-gas heaters requirements in consultation with the
enameller and the end user
for gas-gas heaters if required by the customer
the edge covering of the pair of panels shall be determined
in accordance with EN 14863. The mean has to be agreed
between customer and supplier at the time of ordering
flatness requirement after the enamelling if required in consultation
between enameller and packager
4.35 boiling sulphuric acid Maximum mass loss: test specimens shall be prepared in 1 x per 5 tons frit
2 accordance with EN ISO 28764 and shall
air-gas heaters: 10.0 g/m
2 be pre-treated and enamelled under the
gas-gas heaters: 2.0 g/m
same circumstances as the production
of the heat exchanger plates. They
shall have an enamel layer thickness

of 150 μm ± 20μm.
4.40 thermal shock 5 x 350 °C on test sheets conform to EN ISO 28764,

resistance the resistance is tested on sheets of 1 x per order

100 x 100 mm with an enamel coating
thickness of 150 +/- 20 μm. The sheets

are cooled down in water of 20 °C

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