Category · ASTM C155 Group 23 – 30 · 1260 – 1650 °C

Insulating Fire Bricks (IFB) — Refractory Insulation from India

Insulating fire bricks (IFB) — also known internationally by their JM-series ASTM grades K-23, K-26, K-28 and K-30 — are lightweight refractory bricks fired from porous bonded compositions of alumina, silica and refractory clays. Their defining property is low bulk density (typically 0.45 – 0.85 g/cm³) and consequently low thermal conductivity, which makes them the standard choice for hot-face insulation and back-up insulation in kilns, ovens and reformers. Each grade is rated for a specific maximum service temperature — K-23 to 1260 °C, K-30 up to 1650 °C. firebrickssource.com supplies the full IFB range plus calcium silicate insulation boards, manufactured to ASTM C155 classification standards and exported from Rajkot, Gujarat to industrial buyers worldwide.

Variants in stock

Grades of insulating fire bricks

$K-23 Insulating Refractory Bricks — firebrickssource.com$

K-23 / JM-23

K-23 Insulating Bricks

Entry IFB grade — kiln car insulation, lab furnace lining, ceramic kiln roof.

Density 0.45 – 0.50 Max 1260 °C

$K-26 Insulating Refractory Bricks — firebrickssource.com$

K-26 / JM-26

K-26 Insulating Bricks

Industrial kilns up to 1400 °C, glass annealing lehrs, petrochemical heat treatment.

Density 0.65 g/cm³ Max 1430 °C

$K-28 Insulating Refractory Bricks — firebrickssource.com$

K-28 / JM-28

K-28 Insulating Bricks

High-temperature kiln linings, reheat furnace back-up, steel ladle cover.

Density 0.80 g/cm³ Max 1540 °C

$K-30 Insulating Refractory Bricks — firebrickssource.com$

K-30 / JM-30

K-30 Insulating Bricks

Top IFB grade — hot-face insulation at peak IFB range, glass tank superstructure.

Density 0.85 g/cm³ Max 1650 °C

$Calcium Silicate Refractory Insulation Boards — firebrickssource.com$

CaSi Board

Calcium Silicate Boards

Non-asbestos board insulation — back-up to IFB, pipe and vessel insulation.

Density 0.22 – 0.27 Max 650 – 1000 °C

Properties overview

IFB grades compared

Insulating fire bricks — comparative properties
Grade	Classification	Max temp °C	Bulk density g/cm³	CCS MPa	Typical application
K-23	ASTM C155 Group 23	1260	0.45 – 0.50	≥ 1.0	Kiln car, ceramic kiln roof
K-26	ASTM C155 Group 26	1430	0.65	≥ 1.5	Industrial kilns, glass lehrs
K-28	ASTM C155 Group 28	1540	0.80	≥ 1.7	Reheat furnace back-up
K-30	ASTM C155 Group 30	1650	0.85	≥ 1.8	Glass tank, premium kilns
CaSi Board	Calcium silicate hydrate	650 – 1000	0.22 – 0.27	≥ 0.7	Back-up, pipe, vessel insulation

*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 IFB and refractory insulation are used

Ceramic Kilns

Tunnel kiln roof, shuttle kiln walls, kiln car deck insulation.

Steel Reheat

Reheating furnace back-up, soaking pit lid, ladle cover lining.

Glass Furnaces

Lehr lining, annealing oven, regenerator back-up insulation.

Petrochemical

Hydrogen reformer back-up, cracker furnace insulation, pipe insulation.

Lab & R&D

Muffle furnaces, lab heat-treatment furnaces, prototype kilns.

Power & Boiler

Boiler insulation, gasifier back-up, hot-air duct insulation.

Datasheet

Download IFB datasheet

Complete property table for all four K-grades and calcium silicate board — bulk density, conductivity, PLC, dimensional tolerances.

Download PDF (datasheet)

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