Introduction to powder enameling of hot water tanks
Porcelain enameling of hot water tanks (HWT's), like electrical & solar boilers, started in Europe some decades ago and is nowadays considered as the most durable anti-corrosion coating for warm water equipment.
Studies by the CISP, the Italian enameling association, showed that the expected lifetime of enameled boilers is much longer then alternative coatings like galvanizing and/or organic powder painting.
Initially enameling was exclusively done by means of various liquid application methods, which require large capital investments and a high level of process knowledge & skills on an operational level to obtain a good and constant quality.
The introduction of electrostatic dry powder enamel application for the inside of HWT's, which technology simplifies the enameling process significantly and eliminates virtually all liquid, gaseous and/or solid waste emissions, resulted in growing number of boiler enamelling plants with this technology worldwide.
This webpage, which is a part of Ronald Ditmer's website, is intended to provide newcomers in the enameling industry a comprehensive documents about the features & benefits of the powder enamelling process and the available coating equipment. For further information, please feel free to contact me or visit www.ditmer.nl
Description of enameling process
Porcelain enamel is a glass alike coating which may be applied on a metal substrate in either a liquid or powder form and is cured above 800 degrees Celsius to obtain its excellent corrosion protective properties.
According to the German standard (DIN 4753/3) the enamel layer should be at least 150 and should not exceed 500 microns.
The boilers should be manufactured from an enamelable steel grade and its design & utilized welding methods should be in accordance to the international recognized guide lines.
Comparison of
expected lifetime with various coating methods
Studies by the CISP, the Italian enameling association, showed that compared with alternative corrosion protection methods, like galvanizing, organic powder coating and duplex coatings, a porcelain enamel coating may provide the longest lifetime expectancy for warm water tanks.
Click op the diagram on the right side, to see the CISP results in further details.
Available enamel application methods
The porcelain enamel layer may be applied by means of the following application methods :
- Flow coating
- Liquid spraying
- Vacuum
- Powder spraying
The electrostatic application of dry powder enamels has many benefits versus traditional wet application methods, such as :
Shorter lead time and less process steps, thanks to elimination of enamel preparation and drying.
Almost 100 % material utilization, thanks to automatic recovery of any over-spray powders.
Environmental friendly, because there are no air, waste water or solid waste emissions.
Simple systems with high level of automation helps to reduce your labor cost and guarantee a good and constant finishing quality.
Powder enamel systems require less factory space then all equipment for wet enamel process.
Click here for further information about the benefits of electrostatic dry powder versus wet application methods.
Available powder enameling systems
Depending upon the required hourly productivity, there are two different enameling plant concepts :
- Online solutions for large production quantities.
- Offline solutions for small and medium sized production quantities.
Ditmer Trading & Consulting B.V. is specialized to provide independent consultancy and/or project management to enable trouble-free realization of complete enameling plants for inside coating of hot water tanks with porcelain enamel powder on a turnkey base. Click here for our contact details