Hardness
Calcium and magnesium become a hard deposit on the hot surface.
By problem
Scale in a Steam Boiler: Causes and the Solution
Boiler scale is a hard layer from hardness and silica in the feed water. The layer forms on the hot surface. Scale blocks heat transfer to the water. The boiler burns more fuel, and the tube metal gets too hot.
Why does scale form?
Silica
Silica leaves a hard layer at high temperature. The layer is difficult to remove.
Temperature
As heat rises, dissolved minerals leave the water and stay on the metal.
Low blowdown
Low blowdown concentrates the boiler water. Hardness and silica rise fast.
What damage does scale cause?
Signs
- Fuel use rises for the same steam load.
- Flue gas temperature rises.
- The boiler makes noise, local hot spots, or unsteady steam.
- Water analysis shows hardness or silica above the limit.
- A hard layer is visible on the tube or the tube sheet at a shutdown.
How do you solve it?
Pre-treatment
Softening, or other pre-treatment, lowers hardness before the water enters the boiler.
Internal treatment
A scale inhibitor keeps the remaining hardness in a form you can remove. It does not let the hardness bake onto the metal.
Blowdown control
Regular blowdown dilutes hardness and silica in the boiler water.
Regular water analysis
Check the feed water, the boiler water, and the blowdown together. Select the product and the blowdown from this data.
Our recommended products
These products prevent scale in a steam boiler. This page does not give a dosage. The dosage depends on the water analysis.
Cefopol 1040
Multifunctional Steam Boiler Scale and Corrosion Inhibitor – NSF Approved
It prevents scaling in the boiler water and also protects the metal surfaces against corrosion.
Cefolin 1087
Multifunctional Boiler Water Treatment Chemical – NSF approved
It stabilizes the hardness of the boiler water. Thus, it prevents scaling and keeps the system efficiency.
Cefolin 1040
Multifunctional Steam Boiler and Steam Line Scale and Corrosion Inhibitor
It prevents both scaling and corrosion in the steam boiler and the steam line.
Cefopol 6084
Hardness Stabilizer and Scale Inhibitor in Steam Boilers
It is a hardness stabilizer and scale inhibitor for steam boilers.
Cefopol 6030
Hardness Stabilizer and Scale Inhibitor for Steam Boilers
It is a hardness stabilizer and scale inhibitor for steam boilers.
Cefopol 6035
Hardness Stabilizer and Scale Inhibitor for Steam Boilers
It is a hardness stabilizer and scale inhibitor for steam boilers.
Frequently asked questions
Is boiler scale the same as a hard deposit?
In plant use, both names mean a hard layer on the hot surface. Hardness starts the layer. Time and heat make the layer thick. Both block heat transfer.
How does scale damage a boiler tube?
The layer separates the metal from the water. The flame still heats the tube. The metal cannot cool. The tube can thin or crack. The result is an unplanned stop and a repair.
Does blowdown alone prevent scale?
Blowdown dilutes concentrated boiler water. Blowdown is necessary. Blowdown does not replace softening or internal treatment. The three work together.
How do you select a boiler scale inhibitor?
The selection depends on feed water hardness, silica, boiler pressure, and the blowdown routine. Select the exact product from the water analysis.
We help you select the correct scale inhibitor for your boiler
Send your feed water analysis or your latest boiler water results. Our technical team will reply with a product and a blowdown plan.
We reply to quote requests within 12 hours.