K-28 / JM-28 · ASTM C155 Group 28 · 1540 °C
K-28 Insulating Refractory Bricks
Supplier and exporter from Rajkot, India. High-temperature IFB grade — specified for kiln linings, reheat-furnace back-up and steel ladle cover linings up to 1540 °C.
- Max temp1540 °C
- Bulk density0.80 g/cm³
- CCS≥ 1.7 MPa
- Al₂O₃≈ 65%
- Standard size230 × 114 × 65 mm
- MOQ3 – 5 MT
About this product
What K-28 insulating fire bricks are — and where they fit
K-28 insulating fire bricks (also marketed as JM-28) are high-temperature porous refractory bricks classified ASTM C155 Group 28. The grade is manufactured from selected high-alumina raw materials with approximately 65% Al₂O₃ and is fired to a controlled porous matrix that delivers bulk density of 0.80 g/cm³ — denser than lower K-grades but still firmly in the lightweight insulating refractory category, with thermal conductivity of about 0.42 W/m·K at 1200 °C.
What is K-28? K-28 is the ASTM-classified insulating refractory brick rated for continuous hot-face service up to 1540 °C (2800 °F). The grade was developed to handle applications above the K-23/K-26 temperature ceiling — most notably steel-industry back-up insulation behind dense alumina hot-face, glass-furnace lehrs and tunnels operating above 1400 °C, and high-temperature kiln linings in non-aggressive atmospheres. The higher alumina content gives K-28 better refractoriness under load and lower thermal creep than the lower K-grades.
K-28 is regularly specified as the back-up layer behind 70 – 80% high-alumina hot-face bricks in steel reheat furnaces, and as a hot-face brick in clean atmospheres (kiln roofs, glass-tank superstructure back-up, aluminium remelt furnace lids). At the maximum-temperature end of its rating it is best used as a back-up to a dense refractory rather than as a hot-face — slag, dust and abrasive flue gases will erode the porous structure aggressively.
firebrickssource.com supplies K-28 in the standard 230 × 114 × 65 mm size, plus arches, wedges, splits and machined shapes to drawing. The brick is normally packed shrink-wrapped on heat-treated wooden pallets, edge-protected, with corner boards. The grade is exported regularly to steel mills, glass-works and ceramics manufacturers worldwide. For the top of the IFB temperature range see K-30; for parent category see the IFB index.
Technical specifications
Full property data — K-28 IFB
| Property | Value | Test method |
|---|---|---|
| Classification | ASTM C155 Group 28 | ASTM C155 |
| Max service temperature | 1540 °C (2800 °F) | ASTM C155 |
| Bulk density | 0.80 g/cm³ | ASTM C134 / IS 1528-12 |
| Cold crushing strength (CCS) | ≥ 1.7 MPa | ASTM C133 / IS 1528-4 |
| Modulus of rupture (MOR) | ≥ 1.5 MPa | ASTM C93 |
| Apparent porosity | ≥ 65 % | ASTM C20 / IS 1528-8 |
| Thermal conductivity at 1200 °C | ≈ 0.42 W/m·K | ASTM C182 |
| Permanent linear change at 1510 °C × 24 h | ≤ −1.0 % | ASTM C210 |
| Al₂O₃ content | ≈ 65 % | IS 1528-7 |
| Standard size | 230 × 114 × 65 mm | — |
| Custom sizes | Available on request — arches, wedges, splits, machined shapes | — |
*Typical certified values — actual batch values issued on the per-shipment test certificate. Values aligned with IS 1528 / ASTM C-series / EN 993 test methods.
Applications
Where to use K-28 insulating bricks
- High-temperature kiln linings (up to 1540 °C)
- Steel reheat furnace back-up insulation
- Steel ladle cover and roof lining
- Glass-furnace lehr back-up insulation
- Glass-furnace regenerator hot end back-up
- Hot-blast stove insulation
- Aluminium remelt furnace lid lining
- Ceramic tunnel kiln peak-zone insulation
- Pyrolysis and gasifier back-up insulation
- Furnace door and lid back-up layer
Datasheet
Download technical datasheet
PDF with all certified properties, dimensional tolerances and applicable ASTM / IS test methods. Use this for tender attachments and procurement files.
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Frequently asked
K-28 — questions buyers ask
What is the maximum service temperature for K-28 IFB?
K-28 insulating fire bricks are classified ASTM C155 Group 28 and are rated for hot-face service up to 1540 °C (2800 °F). They are intended for high-temperature kiln and furnace linings where K-23 and K-26 are temperature-marginal.
What is the Al₂O₃ content of K-28?
K-28 has approximately 65% Al₂O₃ — significantly higher than K-23 (~37%) and K-26 (~50%). The elevated alumina is what enables the higher temperature rating and improved refractoriness under load.
Where are K-28 insulating refractory bricks used?
Typical applications include high-temperature kiln linings, reheat furnace back-up insulation, steel ladle cover linings, glass-furnace back-up, hot-blast stove insulation and aluminium remelt furnace lid lining.
What is the thermal conductivity of K-28?
Thermal conductivity at 1200 °C is approximately 0.42 W/m·K. Conductivity rises with temperature; for design heat-loss calculations request the full conductivity-vs-temperature curve from the test certificate.
Can K-28 be used as a hot-face brick at the maximum temperature?
K-28 can be used as a hot-face brick in clean, non-corrosive environments up to 1540 °C. In aggressive environments (slag, dust, abrasion or chemical attack at peak temperature), use a dense refractory at the hot-face and K-28 as the back-up insulation layer.
What is the typical MOQ and packaging?
Standard MOQ is 3 – 5 MT for stocked sizes. IFB is shrink-wrapped on heat-treated wooden pallets, edge-protected, with corner boards. One 20-foot container typically loads 12 – 16 MT of K-28 IFB depending on shape mix.
Do you provide samples and test certificates?
Yes. Samples can be dispatched on request — normally chargeable plus courier. Every production batch is tested for bulk density, cold crushing strength, permanent linear change and thermal conductivity (lot basis); a test certificate ships with the consignment.
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