Water & Wastewater
Valve Enamel Coating
Inner and outer surfaces of gate and butterfly valves, hydrants and fittings. For raw and drinking-water valves, ISO 11177 defines the quality requirements and test methods for the enamel.
Solutions · Wet Enamel
Turnkey Wet Enameling Lines
Inner and outer surface enamel for everything from valves, pipes and fittings to cast iron hob grates, pots and pans: a glass layer fused to the metal at about 830 °C that resists water, soil, salt, chemicals and heat.
System Overview
Glass Against Water, Salt and Chemicals.
Wet enamel is made by spraying a liquid enamel (slip) prepared from glass frit, clay and water onto the part, drying it and firing it at about 830 °C. During firing the glass melts and fuses to the steel or cast iron, forming a hard, glassy surface.
On parts with an internal volume, such as valve bodies and pipes, the liquid enamel also covers the inner surface and recesses. STRONG3000 designs the line as one system — from pretreatment and application booths to drying and firing ovens, conveyors and automation. Powder enamel application can also be set up for the same parts.
Not to be confused with the bitumen- and asphalt-based coatings that the pipe industry also calls “enamel”: vitreous enamel is glass-based and fired in a furnace.
Target Industries
Where Enamel Comes In.
On valves and pipes in constant contact with water, soil, seawater and chemicals, the surface is the only barrier between the metal and its environment. Enamel builds that barrier as a glass layer fused to the metal.
Infrastructure
Underground Water Pipes
In buried water lines the outer surface meets the moisture and salts in the soil, while the inner surface carries the flowing water. Enamel covers both surfaces with a glass layer.
Oil & Gas
Oil Pipes
Lines carrying crude oil, saline produced water and sand need an inner surface that resists both corrosion and wear.
Marine & Chemical
Saline and Chemical Environments
Lines exposed directly to seawater, such as the seawater cooling pipes in a ship’s engine room, and chemical process piping that carries acids and alkalis.
Why Enamel?
A Glass Layer Against Corrosion.
Enamel is not a paint: it is an inorganic glass that bonds chemically to the metal during firing. Its key properties for valves and pipes:
Corrosion Resistance
Covers surfaces in contact with water, seawater and soil with a glass layer fused to the metal.
Chemical Resistance
Resists acids and alkalis; hydrofluoric acid and hot concentrated phosphoric acid are the exceptions.
Smooth Surface
The glassy surface reduces deposits and scale build-up.
Hardness
The hard glass surface resists wear from fluids carrying sand and particles.
Heat Resistance
Its inorganic structure withstands hot water and changes in temperature.
Hygiene
The glass surface is easy to clean and is used on surfaces in contact with drinking water.
Process Flow
From Pretreatment to Firing, One Line.
Application Booths
Dry-Filter Wet Enamel Booths.
Wet enamel is applied with a manual gun in dry-filter booths or automatically in conveyorised line-type booths. The stainless body and efficient air extraction keep the work area clean for the operator.
| Type | Dry-filter manual / conveyorised line-type |
|---|---|
| Air velocity | 0.4 – 0.6 m/s |
| Filtration | Dry-type cardboard/fiber filter |
| Body | Stainless construction |
| Application | Wet enamel (slip) — inner and outer surface |
| Option | Climate room (temperature and humidity control) |
Values are typical ranges; final values are confirmed per project by STRONG3000 engineering.
Booth by Part
Main Coated Products.
Valves are coated in a conveyorised line-type booth; cast iron hob grates, pots and pans in a manual booth with turntables. These are the main examples — for parts from other industries that need wet enamel, the booth and the line are configured to the part.
Conveyorised line-type booth
Valve Bodies and Fittings
Valve bodies, bonnets and fittings pass through the booth on an overhead conveyor, and the wet enamel is sprayed onto the inner and outer surfaces. The booth is sized to the conveyor line and to the drying and firing steps that follow.
- Continuous part flow on an overhead conveyor
- Controlled from the control panel
- Stainless body and lighting
Manual booth · Turntables
Cast Iron Hob Grates
On a hob grate the enamel has to cover every surface, including the undersides of the arms, the edges and the feet. The grates are placed on the turntables of the manual booth, and the operator turns the table to spray the enamel from every angle. Enamel that misses the part collects in trays under the booth, and the booth air passes through a filter.
- Two rotating tables
- Wheeled enamel collection trays
- Filter unit
Manual booth · Turntables
Cast Iron Pots and Casseroles
On pots and casseroles both the deep inner surface and the outer surface are coated; lids are enamelled as separate parts. As the part turns on the table, the enamel also reaches the rims and inner corners.
- Deep inner surface and outer surface
- Lids as separate parts
- Rims and inner corners
Manual booth · Turntables
Cast Iron Frying and Grill Pans
On pans the handle and rims are coated together with recessed surfaces such as the ribs of a grill pan. The operator aims the gun to suit the shape of the part, so the enamel reaches the bottom of the channels.
- Handle and rims
- Grill pan ribs
- Gun angle set to the shape of the part
Core Equipment
Systems That Complete the Line.
Pretreatment
Degreasing and surface preparation suited to steel and cast iron substrates.
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Dry-off Oven
Removes the water from the wet enamel in a controlled way before firing.
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Firing Ovens
Box, conveyor and U-type high-temperature ovens for firing enamel.
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Climate Room
The application area is enclosed in an insulated room with controlled temperature and humidity.
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Automation
Reciprocators, robotics and conveyor control for consistent, high-volume enameling.
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Powder Enamel Option
Automatic system that applies powder enamel to the inner and outer surfaces of pipes.
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Engineering & Manufacturing
Designed. Engineered.
Designed. Engineered.
Manufactured. Under One Roof.
STRONG3000 combines mechanical and electrical engineering, automation, control software and application technology in a single organization — so responsibility for the whole line stays in one place.
Mechanical Engineering
Booths, conveyors, ovens and recovery hardware.
Electrical Engineering
Power, control cabinets and line wiring.
Automation
Reciprocators, robotics and PLC control.
Control Software
Smart AI platform and line integration.
Application Technology
Gun, injector and powder delivery development.
FAT & Commissioning
Factory acceptance testing and on-site start-up.
Reference Project
A Line in the Field.
PROJECT No. 0638
3 photos
Valve & Pipe Wet Enamel Line
Automatic line-type wet enamel plant for the inside and outside of valves and pipes. Filtered, stackless application booths.
Project No.0638
Knowledge Center
More About Wet Enamel.
Fundamentals
What Is Wet Enamel (Slip Enamel)? Enameling by Dipping and Spraying
Applying water-based slip enamel by dipping, flow coating and spraying — for castings and complex geometries.
Application
Enamel Firing (Sintering) Furnaces and Temperatures
The 780–850 °C regime in which enamel fuses to metal, furnace types and energy.
Comparison
The Difference Between Powder Coating, Powder Enamel and Wet Enamel
Which part needs powder coating and which needs enamel? A decision guide based on temperature, durability and cost.
Documentation
Technical Datasheet & Documents.
Turnkey Wet Enameling Lines — Technical Datasheet
PDF · All the technical content of this page
Download PDF · All the technical content of this page
Talk to an Engineer
Planning a Valve or Pipe Enameling Line?
Discuss your part, enamel type and capacity directly with STRONG3000’s engineering team.