K-26 / JM-26 · ASTM C155 Group 26 · 1430 °C
K-26 Insulating Refractory Bricks
Supplier and exporter from Rajkot, India. The mid-range IFB grade — specified for industrial kilns operating up to 1400 °C, glass annealing lehrs and petrochemical heat-treatment furnaces.
- Max temp1430 °C
- Bulk density0.65 g/cm³
- CCS≥ 1.5 MPa
- Thermal conductivity≈ 0.30 W/m·K
- Standard size230 × 114 × 65 mm
- MOQ3 – 5 MT
About this product
What K-26 insulating fire bricks are — and where they fit
K-26 insulating fire bricks (also marketed as JM-26) are lightweight porous refractory bricks classified ASTM C155 Group 26 — the mid-range temperature class in the IFB family. They are manufactured from refractory clays with elevated alumina content (~50% Al₂O₃) and bonded with controlled-burn-out additions to achieve a uniform pore structure. The result is a brick with bulk density of 0.65 g/cm³, approximately 70% porosity, and a thermal conductivity of about 0.30 W/m·K at 1000 °C.
What is K-26? K-26 is the ASTM-classified insulating refractory brick rated for continuous hot-face service up to 1430 °C (2600 °F). It sits one step up from K-23 and is the grade most often specified for industrial kilns whose set-point sits in the 1200 – 1400 °C window — a temperature band where K-23 is marginal and a higher K-grade is over-specified. The grade combines moderate density with reasonable mechanical strength (CCS ≥ 1.5 MPa), making it suitable both as a hot-face insulation brick and as a back-up layer behind denser refractory.
K-26 is regularly used in glass annealing lehrs (where slow controlled cooling demands uniform low-conductivity insulation), petrochemical heat-treatment furnaces, ceramic kiln walls at the warmer end of the kiln, and pyrolysis or carbonisation furnaces. It is also a common back-up choice behind 60 – 70% high-alumina hot-face bricks where the hot-face operates between 1300 and 1450 °C.
firebrickssource.com supplies K-26 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 glass manufacturers in the Middle East and Southeast Asia, petrochemical plants in the Gulf, and ceramics manufacturers worldwide. For higher temperatures see K-28; for back-up boards see calcium silicate.
Technical specifications
Full property data — K-26 IFB
| Property | Value | Test method |
|---|---|---|
| Classification | ASTM C155 Group 26 | ASTM C155 |
| Max service temperature | 1430 °C (2600 °F) | ASTM C155 |
| Bulk density | 0.65 g/cm³ | ASTM C134 / IS 1528-12 |
| Cold crushing strength (CCS) | ≥ 1.5 MPa | ASTM C133 / IS 1528-4 |
| Modulus of rupture (MOR) | ≥ 1.5 MPa | ASTM C93 |
| Apparent porosity | ≥ 70 % | ASTM C20 / IS 1528-8 |
| Thermal conductivity at 1000 °C | ≈ 0.30 W/m·K | ASTM C182 |
| Permanent linear change at 1400 °C × 24 h | ≤ −1.0 % | ASTM C210 |
| Al₂O₃ content | ≈ 50 % | 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-26 insulating bricks
- Industrial kiln linings up to 1400 °C
- Glass annealing lehr hot-face and back-up
- Petrochemical heat-treatment furnaces
- Ceramic kiln hot-face (warm end of cycle)
- Tunnel kiln roof and side walls
- Pyrolysis and carbonisation furnaces
- Back-up insulation behind 60 – 70% alumina hot-face
- Reheating furnace cold-zone insulation
- Heat-treatment furnace lid lining
- Forge and foundry holding furnace insulation
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.
Download K-26 datasheet (PDF)Quote request
Get K-26 quote in 24 hours
Quantity, shape mix, Incoterm — that's all we need. Quote, datasheet and lead time come back the same business day or the next.
Frequently asked
K-26 — questions buyers ask
What is the maximum service temperature for K-26 IFB?
K-26 insulating fire bricks are classified ASTM C155 Group 26 and are rated for hot-face service up to 1430 °C (2600 °F). Continuous-service ratings should always be confirmed against the test certificate and the actual thermal cycling profile.
What is the difference between K-23 and K-26?
K-23 is rated to 1260 °C with bulk density of 0.45 – 0.50 g/cm³. K-26 is rated to 1430 °C, has higher Al₂O₃ (~50%), higher bulk density (~0.65 g/cm³) and higher cold crushing strength (≥ 1.5 MPa). K-26 is specified when service temperature exceeds the K-23 limit or when slightly higher mechanical strength is needed.
Where are K-26 insulating refractory bricks used?
Typical applications include industrial kiln linings up to 1400 °C, glass annealing lehrs, petrochemical heat-treatment furnaces, ceramic kiln hot-face, back-up behind dense refractory and pyrolysis furnace insulation.
What is the standard size of K-26 IFB?
Standard size is 230 × 114 × 65 mm. Arches, wedges, splits and machined shapes are available on request — IFB is easily machined to drawing with carbide tooling.
How does K-26 perform under thermal cycling?
K-26 has good thermal-shock resistance because of its high porosity (≥ 70%). For severely cycled applications, design the lining with appropriate expansion joints and pre-heat profiles, and verify PLC at the operating temperature on the test certificate.
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 10 – 14 MT of K-26 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.
Related products
