RomânăHigh-Temperature Coatings for Chimneys & Thermal Applications
Industrial chimneys, flue gas ducts, and high-temperature processing equipment are exposed to the simultaneous attack of high temperatures, condensing acid flue gases, mechanical stress from thermal cycling, and in some cases abrasive particulate in the gas stream. Standard cementitious materials fail rapidly in these environments - Portland cement loses strength above 300°C and disintegrates above 600°C. Gemite's high-temperature resistant systems use geopolymer, aluminosilicate, and calcium aluminate binders that maintain structural integrity at temperatures from ambient up to 1200°C.
Chimney & Exterior Protection Applications
Flue Gas Condensate Attack
One of the most destructive mechanisms in industrial chimney deterioration is condensate attack. When flue gas temperatures fall below the dew point, sulphur dioxide and nitrogen oxides in the gas stream dissolve in condensed water to form sulphuric and nitric acids - with concentrations that can reach pH 1-2 in severe cases. This condensate attacks Portland cement linings within months. Gemite's acid-resistant chimney linings are specifically formulated to resist condensate attack at the actual flue gas composition and temperature of your installation.
Thermal Cycling & Cracking
Industrial chimneys undergo repeated thermal cycling - heating during operation and cooling during shutdowns. The differential thermal expansion between the structural shell (concrete or masonry) and the interior lining creates mechanical stress that cracks brittle linings. Gemite's chimney lining systems use geopolymer binders with matched thermal expansion coefficients and inherent flexibility to accommodate thermal cycling without cracking - critical for service life in intermittently operated industrial facilities.
Key Performance Characteristics
Temperature Resistance to +1200°C
Calcium aluminate and geopolymer systems provide structural performance at temperatures well above the capability of Portland cement - selected based on the maximum process temperature of the application.
Acid Flue Gas Resistance
Linings for wet flue gas applications (below acid dew point) are specifically tested against the flue gas composition - sulphur dioxide content, moisture content, and temperature - to confirm resistance to condensate attack.
Low Thermal Conductivity
For applications where thermal insulation is required in addition to structural protection, Gemite provides lightweight insulating castables and boards with low thermal conductivity to reduce heat loss and surface temperature.
Structural Repair of Existing Chimneys
For existing chimneys with deteriorated linings, Gemite provides complete rehabilitation systems - from removal of failed lining material through repair of the structural shell and application of a new high-temperature resistant lining.
Chimneys & Exterior Protection - Technical Questions
What is the maximum temperature Gemite chimney linings can withstand?
Temperature resistance depends on the specific system. Polymer-modified cementitious systems: up to 200°C continuous service. Sulphate-resistant calcium aluminate cement systems: up to 600°C. Calcium aluminate castables: 800-1000°C. High-alumina refractory systems: up to 1200°C or higher. The correct system is selected based on the maximum continuous service temperature, the thermal cycling range, and the chemical exposure (flue gas composition). Gemite's technical team specifies the appropriate system after reviewing your process parameters - do not apply standard cementitious systems above 200°C.
How are deteriorated chimney linings rehabilitated?
The rehabilitation procedure depends on the extent of deterioration and the remaining structural condition of the chimney shell. Typical sequence: (1) visual inspection and core testing to assess lining and shell condition; (2) removal of deteriorated lining by hydraulic breaking or hydrodemolition; (3) repair of the structural shell where carbonation, rebar corrosion, or acid attack has occurred; (4) surface preparation of the cleaned substrate; (5) application of the new high-temperature resistant lining in the appropriate thickness; (6) curing and controlled first heating to drive off moisture before full service temperature is reached. Our technical team designs the complete rehabilitation programme for your specific chimney.
Can chimney lining work be carried out during operation?
Chimney lining and rehabilitation work requires the chimney to be taken out of service - both for safety (confined space entry, flue gas residue) and for the curing and first-heating protocol of the new lining. In multi-flue systems, it may be possible to maintain partial plant operation while one flue is rehabilitated. Our project planning team designs the shutdown and recommissioning sequence to minimise production impact, including the controlled first-heating programme to cure the new lining before full operational temperature is applied.
Specifying Lining for an Industrial Chimney or Flue System?
Our specialists review your flue gas composition, process temperature, thermal cycling frequency, and structural condition - then design the complete lining system with application protocol and first-heating programme.
- Temperature and chemical resistance system selection
- Flue gas composition analysis and condensate risk assessment
- Thermal cycling and structural movement accommodation
- Shutdown planning and first-heating protocol
Or contact us: office@gemite.tech · +40 232 273 031