This document specifies the classification grades, shapes and dimensions, technical requirements, test methods, inspection rules, packaging, marking, transportation, storage, and quality certificate for silica bricks.
This document is applicable to silica bricks used in glass kilns, coke ovens, and hot-blast stoves. Silica bricks used in other kilns and furnaces may refer to this document.
The contents of the following documents constitute indispensable provisions of this document through normative reference in this text. For dated references, only the edition cited applies to this document. For undated references, the latest edition (including all amendments) applies to this document.
GB/T 2992.1, Shape and Dimensions of Refractory Bricks—Part 1: Standard Bricks
GB/T 2997, Dense Shaped Refractory Products—Determination of Bulk Density, Apparent Porosity and True Porosity
GB/T 5071, Refractory Materials—Determination of True Density
GB/T 5072, Refractory Materials—Determination of Cold Crushing Strength
GB/T 5073, Refractory Materials—Determination of Creep in Compression
GB/T 5988, Refractory Materials—Determination of Permanent Change in Dimensions on Heating
GB/T 5990, Refractory Materials—Determination of Thermal Conductivity, Specific Heat Capacity and Thermal Diffusivity (Hot-Wire Method)
GB/T 6901, Chemical Analysis Methods for Siliceous Refractories
GB/T 7320, Refractory Materials—Determination of Thermal Expansion
GB/T 7321, Method for Preparation of Test Pieces of Shaped Refractory Products
GB/T 10325, Rules for Acceptance Sampling Inspection of Shaped Refractory Products
GB/T 10326, Inspection Methods for Dimensions, Appearance and Cross Section of Shaped Refractory Products
GB/T 16546, General Rules for Packaging, Marking, Transportation, Storage and Quality Certificate of Shaped Refractory Products
GB/T 18930, Terminology for Refractories
GB/T 20511, Rules for Classification of Refractory Products
GB/T 21114, Refractory Products—Chemical Analysis by X-ray Fluorescence (XRF)—Fused Cast-Bead Method
YB/T 172, Quantitative Phase Analysis of Silica Bricks—X-ray Diffraction Method
YB/T 370, Refractory Materials—Test Method for Refractoriness Under Load (Non-Differential, Rising Temperature Method)
The terms and definitions defined in GB/T 18930, as well as the following, apply to this document.
melt index
The sum of the mass fraction of alumina, w(Al₂O₃), and twice the sum of the mass fractions of potassium oxide and sodium oxide, w(K₂O) and w(Na₂O), i.e.:
w(Al₂O₃) + 2[w(K₂O) + w(Na₂O)].
Silica bricks are divided by principal application into three categories: silica bricks for glass kilns, silica bricks for coke ovens, and silica bricks for hot-blast stoves. According to physicochemical indexes, they are divided into six grades.
Silica bricks for glass kilns include three grades: BG-96a, BG-96b, and BG-95.
Silica bricks for coke ovens include two grades: JG-95H and JG-94.
Silica bricks for hot-blast stoves include one grade: RG-95.
Among these, “G”, “B”, “J”, and “R” are the initial letters of the Chinese pinyin for “silica”, “glass”, “coke”, and “hot”, respectively. The number that follows indicates the mass fraction of silicon dioxide. The letters a and b indicate product class, and H indicates high thermal conductivity.
The shapes and dimensions of silica bricks shall comply with GB/T 2992.1 and GB/T 20511, and may also be manufactured according to drawings provided by the purchaser.
5.1.1 The physicochemical indexes of silica bricks for glass kilns shall comply with the provisions of Table 1.
5.1.2 The dimensional tolerances and appearance of silica bricks for glass kilns shall comply with the provisions of Table 2.
5.1.3 For special requirements concerning key bricks, extra-special-shaped bricks, and other products, the supplier and purchaser shall negotiate separately.
Table 1 — Physicochemical Indexes of Silica Bricks for Glass Kilns
| Item | Index | |||
|---|---|---|---|---|
| BG-96a | BG-96b | BG-95 | ||
| w(SiO₂) / % | μ₀ | ≥96 | ≥96 | ≥95 |
| σ | 0.8 | 0.8 | 1 | |
| w(Fe₂O₃) / % | μ₀ | ≤0.5 | ≤0.8 | ≤1.0 |
| σ | 0.2 | 0.2 | 0.2 | |
| Melt index / % | μ₀ | ≤0.5 | ≤0.7 | — |
| σ | 0.15 | 0.15 | — | |
| Apparent porosity / % | μ₀ | ≤21 | ≤22 | |
| σ | 1.5 | 1.5 | ||
| True density / (g/cm³) | μ₀ | ≤2.34 | ||
| σ | 0.1 | |||
| Cold crushing strength / MPa (each measured value shall be greater than the specified Xmin value) |
μ₀ | ≥40 | ≥35 | ≥30 |
| σ | 10 | 10 | 10 | |
| Xmin | 30 | 25 | 20 | |
| Initial softening temperature under load at 0.2 MPa / °C | μ₀ | ≥1680 | ≥1670 | ≥1670 |
| σ | 13 | 13 | 13 | |
| Permanent linear change on heating (1450 °C, 2 h) / % | Xmin − Xmax | 0 – 0.2 | ||
| Residual quartz / % | μ₀ | ≤2.0 | ||
| σ | 0.5 | |||
Unit: mm
| Item | Index | ||
|---|---|---|---|
| Dimensional tolerance | Thickness | ±2 | |
| Length and width ≤350 | ±3 | ||
| Length and width >350 | ±4 | ||
| Warpage | Length ≤350 | ≤1.5 | |
| Length >350 | ≤12 (maximum shall not exceed 0.5% of the length) | ||
| Difference between corresponding edges, Thickness | ≤1.0 | ||
| Wedge taper | ≤1.5 | ||
| Length of chipped corners and edges (a+b+c), (e+f+g) |
Working face | ≤40 | |
| Non-working face | ≤60 | ||
| Pit diameter | Working face | ≤5 | |
| Non-working face | ≤10 | ||
| Crack length | Width ≤0.1 | Unrestricted | |
| Width 0.11 – 0.25 | working face | ≤50 | |
| non-working face | ≤80 | ||
| Width 0.26 – 0.5 | working face | ≤30 | |
| non-working face | ≤50 | ||
| Width >0.5 | Not permitted | ||
Where a crack crosses an edge, it is only permitted to cross one edge; edge-crossing cracks shall not be combined in the calculation. For stretcher bricks, the length of a crack parallel to the working face shall not exceed one-fifth of the common edge length between the crack-bearing face and the working face.
No broken cross section or lamination cracks shall be allowed.
When the dimensional difference between the large end and small end of a wedge brick is ≤7 mm, a clear mark shall be made on the large and small ends of the brick.
Note: At the request of the user, grading may be carried out according to one principal dimension of the brick.
5.2.1 The physicochemical indexes of silica bricks for coke ovens shall comply with the provisions of Table 3.
5.2.2 The dimensional tolerances and appearance of silica bricks for coke ovens shall comply with the provisions of Table 4.
5.2.3 For special requirements concerning key bricks, extra-special-shaped bricks, and other products, the supplier and purchaser shall negotiate separately.
| Item | Index | Index | |||
|---|---|---|---|---|---|
| JG-94 | JG-95H | ||||
| Hearth (LD) | Wall (LB) | Other Parts (QT) | |||
| w(SiO₂) / % | μ₀ | ≥94.5 | ≥94.5 | ≥94.0 | ≥95.0 |
| σ | 1 | 1 | 1 | 1 | |
| w(Al₂O₃) / % | μ₀ | ≤1.0 | ≤1.0 | ≤1.0 | ≤1.0 |
| σ | 0.3 | 0.3 | 0.3 | 0.3 | |
| w(Fe₂O₃) / % | μ₀ | ≤1.0 | ≤1.0 | ≤1.0 | ≤0.8 |
| σ | 0.2 | 0.2 | 0.2 | 0.2 | |
| w(CaO) / % | μ₀ | ≤3.0 | |||
| σ | 0.35 | 0.35 | 0.35 | 0.35 | |
| w(Na₂O+K₂O) / % | μ₀ | ≤0.35 | ≤0.35 | ≤0.35 | ≤0.35 |
| σ | 0.04 | 0.04 | 0.04 | 0.04 | |
| Apparent porosity / % | μ₀ | ≤22 | ≤22 | ≤24(26)a | ≤21 |
| σ | 1.5 | 1.5 | 1.5 | 1.5 | |
| Cold crushing strength / MPa (each measured value shall be greater than the specified Xmin value) | μ₀ | ≥40 | ≥35 | ≥28 | ≥45 |
| σ | 10 | ||||
| Xmin | 30 | 25 | 20 | 30 | |
| Initial softening temperature under load at 0.2 MPa / °C | μ₀ | ≥1650 | |||
| σ | 13 | 13 | 13 | 10 | |
| True density / (g/cm³) | μ₀ | ≤2.33 | ≤2.33 | ≤2.34 | ≤2.33 |
| σ | 0.1 | 0.1 | 0.1 | 0.1 | |
| Residual quartz / % | μ₀ | ≤1.0 | ≤1.0 | ≤1.0 | ≤1.0 |
| σ | 0.5 | 0.5 | 0.5 | 0.5 | |
| Permanent linear change on heating (1450 °C, 2 h) / % | Xmin − Xmax | 0 – 0.2 | |||
| Thermal expansionb (1000 °C) / % | μ₀ | ≤1.28 | ≤1.28 | ≤1.30 | ≤1.25 |
| σ | 0.05 | 0.05 | 0.05 | 0.05 | |
| Thermal conductivity (1100 °C) / [W/(m·K)] | μ₀ | — | ≥2.35 | ||
a) The values in parentheses are the indexes for extra-special-shaped bricks.
b) Thermal expansion is a reference value.
Unit: mm
5.3.1 The physicochemical indexes of silica bricks for hot-blast stoves shall comply with the provisions of Table 5.
5.3.2 The dimensional tolerances and appearance of silica bricks for hot-blast stoves shall comply with the provisions of Table 6.
5.3.3 For special requirements concerning extra-special-shaped bricks and other products, the supplier and purchaser shall negotiate separately.
| Item | Index | ||
|---|---|---|---|
| RG-95 | |||
| Dome and Wall Bricks | Checker Bricks | ||
| w (SiO2) / % | μo | ≥95 | ≥95 |
| σ | 1 | 1 | |
| w (Al2O3) / % | μo | ≤1.0 | ≤1.0 |
| σ | 0.3 | 0.3 | |
| w (Fe2O3) / % | μo | ≤1.0 | ≤1.0 |
| σ | 0.2 | 0.2 | |
| Apparent porosity / % | μo | ≤22 | ≤24 |
| σ | 1.5 | 1.5 | |
| True density / (g/cm³) | μo | ≤2.33 | ≤2.34 |
| σ | 0.1 | 0.1 | |
| Cold crushing strength / MPa (each measured value shall be greater than the specified Xmin value) | μo | ≥40 | ≥30 |
| σ | 10 | 10 | |
| Xmin | 25 | 25 | |
| Initial softening temperature under load at 0.2 MPa / °C | μo | ≥1650 | ≥1650 |
| σ | 13 | 13 | |
| Residual quartz / % | μo | ≤1.0 | ≤1.0 |
| σ | 0.5 | 0.5 | |
| Creep rate at 0.2 MPa (1550 °C, 0 h – 50 h) / % | μo | ≤0.8 | ≤0.8 |
| σ | 0.1 | 0.1 | |
| Thermal expansion (1000 °C) / % | μo | ≤1.26 | ≤1.26 |
| σ | 0.05 | 0.05 | |
Unit: mm
| Item | Index | ||||
|---|---|---|---|---|---|
| Dome and Wall Bricks | Checker Bricks | ||||
| Working Face | Non-working Face | Working Face | Non-working Face | ||
| Dimensional tolerance | Size <150 | ±2 | ±2 | Length and width +1, -3 Height ±3 Hole diameter tolerance ±1 |
|
| Size 150 – 345 | ±3 | ±3 | |||
| Size >345 | ±4 | ±4 | |||
| Warpage | Length ≤345 | ≤1.5 | ≤1.5 | — | — |
| Length >345 | ≤2.5 | ≤2.5 | — | — | |
| Wedge difference | ≤1.5 | ≤1.5 | — | — | |
| Difference between corresponding edges (thickness) | ≤1.0 | ≤1.0 | ≤1.0 | ≤1.0 | |
| Length of chipped corners (a+b+c) and chipped edges (e+f+g) | ≤60 | ≤80 | ≤40 | ≤40 | |
| Pit diameter | ≤5 | ≤8 | ≤5 | ≤8 | |
| Crack length | Width ≤0.10 | unrestricted | unrestricted | unrestricted | unrestricted |
| Width 0.11 – 0.25 | ≤60 | ≤70 | ≤30 | ≤30 | |
| Width 0.26 – 0.5 | not permitted | ≤70 | not permitted | not permitted | |
| Width >0.5 | not permitted | not permitted | — | — | |
Where two or more chipped corners, chipped edges, or cracks appear on the same brick, each individual defect shall be assessed at 0.7 times the specified value in the table.
For dome bricks, a crack parallel to the working face shall not exceed one-half of the common edge length between the crack-bearing face and the working face. Edge-crossing cracks shall not be combined in the calculation.
No broken cross section or lamination cracks shall be allowed.
For checker bricks, so long as 10 bricks stacked one above another can form a vertical solid column, projections, bending, taper, etc. are permitted. Where the size of checker bricks exceeds 250 mm, the dimensional tolerances shall be agreed upon by the supplier and purchaser.
Note: At the request of the user, grading may be carried out according to one principal dimension of the brick.
6.1 Test specimens shall be prepared in accordance with GB/T 7321.
6.2 Chemical composition shall be determined in accordance with GB/T 6901 or GB/T 21114.
6.3 Apparent porosity shall be determined in accordance with GB/T 2997.
6.4 True density shall be determined in accordance with GB/T 5071.
6.5 Cold crushing strength shall be determined in accordance with GB/T 5072.
6.6 Initial softening temperature under load shall be determined in accordance with YB/T 370.
6.7 Permanent linear change on heating shall be determined in accordance with GB/T 5988.
6.8 Thermal expansion shall be determined in accordance with GB/T 7320.
6.9 Thermal conductivity shall be determined in accordance with GB/T 5990.
6.10 Creep rate shall be determined in accordance with GB/T 5073.
6.11 Residual quartz shall be determined in accordance with YB/T 172.
6.12 Appearance, dimensions, and cross section shall be inspected in accordance with GB/T 10326.
Products shall be grouped into lots by grade, and each lot shall not exceed 500 t.
7.2.1 Acceptance sampling and conformity determination of the products shall be carried out in accordance with GB/T 10325.
7.2.2 The inspection items for the products are as follows:
— For silica bricks for glass kilns: chemical composition, apparent porosity, cold crushing strength, initial softening temperature under load, and residual quartz;
— For silica bricks for coke ovens: chemical composition, apparent porosity, cold crushing strength, initial softening temperature under load, residual quartz, and in addition, thermal conductivity for JG-95H;
— For silica bricks for hot-blast stoves: chemical composition, apparent porosity, cold crushing strength, creep rate, and residual quartz.
Conformity assessment may take the form of a supplier’s declaration, user recognition, or third-party certification.
8.1 Packaging, marking, transportation, and storage of the products shall be in accordance with GB/T 16546. The delivery condition and packaging form shall be determined through negotiation between the supplier and purchaser.
8.2 When products are dispatched, they shall be accompanied by a quality certificate issued by the supplier’s quality department and product instructions for use. The quality certificate shall specify the supplier’s name, purchaser’s name, production date, shelf life, shipping date, contract number, document number of this standard, product name, grade, batch number, and the corresponding physicochemical test results.
