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Differences Between SK32, SK34, SK36, SK38 and SK40 Fire Bricks
1. Brief Introduction to SK Grade Fire Bricks
SK grade is a standard classification for clay and high alumina refractory bricks, which mainly reflects the refractory temperature and alumina content of fire bricks. The larger the SK number, the higher the alumina content, refractoriness and high-temperature bearing capacity of the brick.
SK32 and SK34 are common fire clay bricks with moderate alumina content, suitable for medium-temperature kiln environments. SK36, SK38 and SK40 are high alumina refractory bricks produced from bauxite aggregates, featuring outstanding high-temperature resistance, stable volume and excellent corrosion resistance, widely applied in various high-temperature industrial furnaces.
2. Core Technical Performance of Each SK Series Brick
SK32 Fire Brick
Alumina content minimum 48%, iron oxide content below 3.0%. Refractoriness reaches 1770℃, load softening temperature above 1300℃. It has stable thermal shock resistance and low cost, mainly used for low and medium temperature furnace linings, flues and auxiliary kiln structures.
SK34 Fire Brick
Alumina content no less than 55%, iron oxide controlled within 2.5%. Refractoriness 1770℃, load softening temperature up to 1360℃. Better high-temperature strength than SK32, fit for medium-temperature kilns, heat preservation sections of rotary kilns and boiler inner walls.
SK36 Fire Brick
Alumina content ≥65%, iron oxide ≤1.8%. Refractoriness 1770℃, load softening temperature over 1450℃. Belongs to entry-level high alumina brick, with stronger slag erosion resistance, ideal for medium-high temperature kiln lining, cement kiln preheating zone and annealing furnace.
SK38 Fire Brick
Alumina content ≥75%, iron oxide ≤1.6%. Refractoriness up to 1790℃, load softening temperature above 1520℃. Great high-temperature mechanical strength and thermal stability, widely used in high-temperature calcination sections, glass kilns and metallurgical furnaces.
SK40 Fire Brick
Alumina content ≥80%, iron oxide ≤1.5%. The top grade of SK series fire bricks, refractoriness 1790℃, load softening temperature reaches 1550℃. Outstanding resistance to high temperature, molten slag and thermal cycling, suitable for ultra-high temperature kiln working layers, furnace outlet and severe erosion positions.
3. Main Application Scenarios of SK Series Fire Bricks
- Building materials industry: Cement rotary kilns, ceramic kilns, brick firing kilns, lime kilns.
- Metallurgical industry: Heating furnaces, annealing furnaces, smelting furnace linings, ladle linings.
- Thermal power industry: Industrial boilers, boiler flues, furnace walls and insulation layers.
- Chemical industry: High-temperature reaction furnaces, calcining furnaces and thermal insulation equipment.
4. How to Choose Suitable SK Grade Fire Bricks
- Confirm long-term working temperature: Select SK32/SK34 for temperature below 1300℃; choose SK36 for 1300–1450℃; adopt SK38/SK40 for long-term service above 1450℃.
- Check slag corrosion condition: Furnaces with serious molten slag erosion need high-alumina SK38 or SK40 bricks.
- Consider load bearing: Positions bearing heavy high-temperature loads require SK grades with higher load softening temperature such as SK38 and SK40.
- Budget matching: Fire clay bricks SK32 and SK34 have lower prices for ordinary thermal insulation parts; high alumina bricks are used for key working layers.
5. Product Advantages of Our SK Series Fire Bricks
- Stable raw material composition, strictly controlled alumina and iron oxide indexes to guarantee consistent performance.
- High cold crushing strength, low apparent porosity, good anti-permeability against high-temperature gas and slag.
- Excellent thermal shock resistance, not easy to crack or peel under frequent temperature rise and fall.
- Complete specifications of standard bricks and special shaped bricks, customizable according to customer kiln drawing requirements.
- Matched refractory mortar for masonry provided together, supporting one-stop refractory lining solution.
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