Coating abnormal case study (24), epoxy phenol aldehyde paint off!

Defect Description:
GCT004/005/006ZI
silencer internal anti-corrosion coating project completed in

May


Overall coating and repair, construction using electric polishing, Capolain
187
paint spray two (bottom painted red, paint gray white), design coating thickness
300 m
,
a large
area of failure of the
contact coating with air on the outside of the silencer during the internal inspection of the open equipment during the overhaul in march
, 2014 (see figure below). The inner coating is intact.
conditions description:
1
,
GCT
operating conditions up to
296
degrees C, Capolain
187
maximum temperature of
204
degrees C
China
.
2
, the outer coating directly in contact with the atmosphere, sunlight, winter temperature reached minus
20
degrees Celsius.
3
, in operating conditions may be hot and cold, once or twice a year.
the above description, please give personal analysis and paint improvement selection recommendations.Tanyou"
shisiye
" reply:
illustration can be seen peeling coating is paint, still can see the red primer, the same is the coating inside the silencer, the inner coating is intact, the outer coating peeled off, certainly the coating should not be a construction problem, the outside of the silencer contact with the atmosphere, extremely hot and cold, and the inside is in the steam port. I suspect that the paint is not resistant to high and low temperatures. Despise fools and expect high people to give more detailed answers. It is also hoped that the owner can give
187
paint performance manual, in addition to the silencer inside and outside paint second-degree construction detailed records.Tanyou " hardened tile" reply:
by the picture visible primer and paint between the layer adhesion is no problem, on the other is the primer and substrate no adhesion, personal opinion is:
1
, due to the rapid heat, substrate and paint deformation out of step resulting in loss of adhesion;
2
, manual grinding roughness is not enough, but also weakened adhesion;
3
, direct contact with the external environment, corrosion conditions are much worse than the internal.
4
, paint temperature resistance index can not meet the environmental requirements of use.Let's first look at the instructions section of Capolain epoxy phenol finish
Phenoline 187 Finish
:
Properties: Amine-cured modified epoxy phenol coatings
Product Overview:
Highly cross-linked coatings, resistant to chemical corrosion. It is widely used in petrochemical industries such as tank storage, as well as as as as as part of tank lining systems in other immersion environments such as jet fuel, urban construction and industrial wastewater treatment.
characteristics:
- excellent chemical corrosion resistance;
- very good wear resistance and bending resistance;
-
VOC
emissions in line with the current
AIM
regulations;
- temperature resistance under insulation conditions up to
204
degrees C;
- Meets the
FDA 21CFR 175.300
food contact standard;
colors: gray
(C703)
, white
(1898)
gloss: matte
matching primer: usually with
Phenoline 187 Primer
, self-paint. An additional
187 Finish
can be used to meet specifications or improve service life.
analysis of 10 birds that:
1,
coating thickness (
300
microns), intense temperature is the main cause of coating shedding failure. Incoheration between the coating and the substrate during temperature change can cause the coating to crack and fall off. The thicker the coating, the thinner the substrate and the faster the temperature change, the more likely it is that the coating will crack and fall off. It is recommended that the total thickness of the general heat-resistant coating should not exceed
150
microns;
2,
hand-polished surface treatment quality is not enough, roughness is not enough, but also weakened the adhesion of the coating to the substrate;
3,
the product's description mentions that "insulation conditions can withstand temperature up to
204
degrees C", and the coating under the insulation layer is slow

to withstand the temperature change; Perhaps because: the temperature is less intense; the substrate is thicker; and the coating is more elastic (more stretching) in wet conditions.