This standard has been drafted in accordance with the rules provided in GB/T 1.1-2009.
Please note that certain content in this document may relate to patents. The issuing organization of this document assumes no responsibility for identifying such patents.
This standard is proposed and under the jurisdiction of the National Technical Committee on Refractories Standardization (SAC/TC193).
This standard specifies the terms and definitions, grades and dimensions, technical requirements, test methods, quality evaluation procedures, packaging, marking, transportation, storage, and quality certificates for insulating mullite refractory bricks.
It applies to insulating mullite refractory bricks used in thermal kiln insulation layers or in working layers not directly exposed to high-temperature molten materials.
The following documents are essential for the application of this standard. For dated references, only the edition cited applies. For undated references, the latest edition (including all amendments) applies.
GB/T 2992.1: Shapes and sizes of refractory bricks—Part 1: General bricks
GB/T 2998: Test methods for bulk density and true porosity of shaped insulating refractory products
GB/T 5072: Test methods for cold crushing strength of refractory materials
GB/T 5988: Test methods for permanent linear change of refractory materials on heating
GB/T 5989: Test methods for refractoriness under load—Differential heating method
GB/T 6900: Methods of chemical analysis for alumino-silicate refractory materials
GB/T 7321: Sample preparation methods for shaped refractory products
GB/T 10325: Rules for sampling inspection of shaped refractory products
GB/T 10326: Methods for inspecting dimensions, appearance, and cross-sections of shaped refractory products
GB/T 16546: Packaging, marking, transportation, and storage of shaped refractory products
GB/T 21114: Chemical analysis of refractory materials using X-ray fluorescence spectroscopy—Glass bead method
GB/T 32833: Test method for spalling resistance of insulating refractory bricks
YB/T 4130: Test methods for thermal conductivity of refractory materials—Water flow flat plate method
A type of alumino-silicate insulating refractory brick with mullite as the primary crystalline phase.
Insulating mullite refractory bricks are classified into seven grades: MG-23, MG-25, MG-26, MG-27, MG-28, MG-30, and MG-32. The letters M and G are derived from the pinyin initials for “mullite” and “insulation” , respectively. The numbers represent the classification based on the heating permanent linear change test temperature, as specified in Table 1.
Table 1: Classification of Insulating Mullite Refractory Bricks
Brick shapes and dimensions shall comply with the requirements of GB/T 2992.1, or be manufactured according to the buyer’s drawings.
5.1 The physical and chemical properties of bricks shall meet the specifications in Table 2.
Table 2: Physical and Chemical Properties of Insulating Mullite Refractory Bricks
5.2 Dimensional tolerances and appearance requirements shall comply with Table 3 (unit: mm).
Table 3: Dimensional Tolerances and Appearance of Insulating Mullite Refractory Bricks
6.1 Sample preparation shall follow GB/T 7321.
6.2 Chemical composition analysis shall be conducted according to GB/T 6900 or GB/T 21114.
6.3 Bulk density shall be tested as per GB/T 2998.
6.4 Cold crushing strength shall be measured following GB/T 5072.
6.5 Permanent linear change upon heating shall follow GB/T 5988.
6.6 Thermal conductivity shall be tested according to YB/T 4130 (water flow flat plate method).
6.7 Refractoriness under load shall be determined using GB/T 5989.
6.8 Spalling resistance shall be tested in accordance with GB/T 32833.
6.9 Dimensions, appearance, and cross-sections shall be inspected per GB/T 10326.
Bricks shall be grouped by grade, with each batch not exceeding 30,000 pieces.
Sampling and acceptance shall be conducted as per GB/T 10325. Bulk density, cold crushing strength, permanent linear change upon heating, and thermal conductivity (average temperature of 350°C) are mandatory inspection items.
Conformity may be determined through supplier declarations, customer validation, or third-party certification.
8.1 Packaging, marking, transportation, and storage shall comply with GB/T 16546, with special conditions agreed upon by the supplier and customer.
8.2 A quality certificate, issued by the supplier’s quality department, must accompany the product upon delivery. It shall include the supplier’s name, customer’s name, shipping date, contract number, product name, applicable standard number, grade, brick number, and results of physical and chemical property tests.
