Seamless coating inside and outside: VAG sets new quality standard for hydrants
Up to now, underground hydrants have mainly been coated with 2 coating systems, inside enamelled and outside epoxy. The seams of the two coating systems and the resulting defects were unavoidable. The new VAG standard is a complete epoxy powder coating (EPP). It eliminates seams between 2 coating systems and thus provides even better protection against corrosion. For standpost hydrants, the upper column outside is provided with an additional UV protection made of red-coloured polyester material on the outside.
By concentrating exclusively on epoxy coatings, VAG GmbH has raised its hydrant range to a new level. With hydrants, the area behind the seat bushing was previously uncoated.
Since the beginning of 2018, all underground and standpost hydrants have been EPP-coated both inside and outside in a single process step. This results in a completely closed coating with perfect corrosion protection in accordance with GSK approval. VAG has been a member of GSK (Quality Association for Heavy Duty Corrosion Protection) for decades and thus relies on the high GSK quality standard.
With the manufacturing process, for which VAG has invested in a new coating plant at the production site in Hodonín (Czech Republic), the focus is on quality and resource conservation. Instead of the previous heating to over 700 °C (during enamelling), the housing parts are tempered to around 220 °C. Robots dip them in a powder basin. Melting the powder produces a uniform blue coating all over, which adheres optimally to the housing material and meets the highest requirements for drinking water hygiene. The layer thickness of at least 250 μm guarantees a non-porous result according to GSK criteria.
With standpost hydrants, one process step follows directly on from the EPP coating. The upper column is sprayed with a special polyester powder at a temperature of just under 200 °C. The resulting red top coating is firmly bonded to the blue primer. It has an additional layer thickness of 80-100 µm and protects the visible parts of the hydrant from UV radiation and surface fading.
This manufacturing process ensures minimum impact sensitivity. Unlike enamel coating, possible damage can be easily repaired. Higher elongation values and thus a better adaptation to the casting material under pressure reduce the risk of cracking of the coating.
As of now, the new coating is standard for VAG hydrants of all types and nominal widths.
The blue lower columns of the VAG NOVA Standpost Hydrants stand for improved corrosion protection and thus a significant increase in the quality of VAG valves.