The thickness standard of clay firebrick usually depends on the specific use scenario and requirements, in general, the thickness of clay firebrick can be determined according to the following aspects:

1. Kiln structure: In different parts of the kiln, clay firebricks of different thicknesses need to be used. For example, the furnace bottom, furnace wall, furnace top and other parts of the furnace may require different thicknesses of refractory bricks to withstand different temperatures and thermal stresses.

2. Use temperature: Determine the thickness of the clay firebrick according to the use temperature it needs to withstand. Generally speaking, the greater the thickness of a refractory brick, the stronger its ability to withstand high temperatures.

3. Thermal conductivity: The thickness is determined according to the thermal conductivity that needs to be controlled. Thicker firebricks can provide better insulation.

4. Structural design: According to the specific structural design and requirements to determine the thickness of clay firebrick, to ensure that it can withstand the corresponding mechanical and thermal stress.

Generally speaking, the thickness of clay firebricks can be between 25mm and 230mm, and the specific thickness needs to be determined according to the actual situation. When selecting the thickness of clay firebrick, it is recommended to consult a professional engineer or choose according to relevant standards and specifications to ensure that it meets the requirements of use and has good fire resistance.