Understanding Different Types of Fire Bricks and Refractory Mortar

Jul 7, 2023

Fire bricks are specialty bricks made from heat-resistant ceramic materials that can withstand high temperatures. They are used to line and insulate furnaces, kilns, fireplaces, barbecues and other structures exposed to high heat.

Aluminum refractory bricks

List the types of fire bricks

There are different types of fire brick suitable for various temperature and insulation needs. The main types include:

Hard fire brick: Made from high-alumina clays and able to withstand temperatures up to 2,400°F. They are used for kilns, furnaces and incinerators requiring the highest level of thermal shock resistance.
• Medium duty fire bricks: Developed for temperatures between 1,800°F to 2400°F. They are composed of fire clay and used in applications with intermittent high heat exposure.
• Acid resistant fire bricks: Formulated with certain metal oxides that inhibit corrosion from acidic gases. They are suitable for environments with sulfur and gases below 1,100°F.
• Soft fire clay bricks: Capable of handling up to 1,800°F. They are composed mostly of fire clay and used for general purpose, moderate temperature applications.
• Insulating fire brick: Made with lightweight expanded aggregates that trap air for insulation. They are rated for temperatures up to 2,000°F and used to line the walls of high temperature ovens and furnaces.

Based on the maximum operating temperature by refractory firebrick mortar

Fire bricks are installed using refractory firebrick mortar, a specialized high-temperature cement. There are different grades of refractory mortar for firebrick based on the maximum operating temperature:

• Low duty (1100°F – 1800°F): Used for applications below 1800°F like fireplaces, barbecues and incinerators.
• Medium duty (1800°F – 2600°F): Suitable for kilns, furnaces and ovens operating up to 2600°F.
• High duty (over 2600°F): Developed for extremely high temperatures over 2600°F encountered by industrial furnaces and glass melting furnaces.

Refractory mortar is typically made from a mix of refractory aggregates, fire clay and binders that withstand heat and thermal expansion. It hardens to form a solid, heat-resistant joint between fire bricks.

When selecting fire bricks and mortar for an application, consider:

• Maximum operating temperature: Choose fire bricks and mortar rated for temperatures at least 200°F higher than the maximum operating temperature. This allows for thermal shock and occasional overheating.
• Thermal cycling: If the application involves frequent heating and cooling cycles, select fire bricks with higher thermal shock resistance.
• Acid resistance: For acidic environments, choose acid resistant fire bricks and mortar formulated with metal oxides to inhibit corrosion.
• Insulation needs: Insulating fire bricks provide an air gap for better insulation and lower heat losses, suitable for high temperature ovens and furnaces.
• Material expansion: Choose refractory mortar with an expansion coefficient that matches the fire bricks to minimize material stresses during heating.
• Quality: the most of consideration is about products quality. Meanwhile, China refractory mortar factory may ensure advanced quality when comparing to other small factories.

Conclusion of  selecting and installing fire bricks and refractory mortar

Properly selecting and installing fire bricks and refractory mortar can extend the lifespan of a high temperature structure and improve its efficiency. Regular inspection for cracks and damaged bricks is recommended, with periodic replacement of damaged materials as needed.