What do K-23, K-26 and K-30 mean in insulating fire brick nomenclature?

K-23, K-26, K-28, K-30 and K-32 are standard ASTM C-155 classifications based on maximum service temperature: K-23 = 1260°C (2300°F), K-26 = 1430°C (2600°F), K-28 = 1540°C, K-30 = 1650°C, K-32 = 1760°C. The "K" stands for kiln temperature class. Higher K-numbers mean higher service temperature but also higher thermal conductivity.

How much energy can an IFB lining save versus a dense brick lining?

A typical retrofit replacing 230 mm of dense fireclay back-up with an equivalent IFB layer reduces shell heat loss by 30–50% and cuts furnace energy consumption by 8–15% in continuous operation. Payback on the IFB upgrade is usually 12–24 months for furnaces running more than 5000 hours per year.

Can IFBs be used as a hot-face lining?

Only in low-duty service, heat treatment furnaces, ceramic kilns, laboratory furnaces and lehrs where there is no contact with liquid metal, slag, abrasive load or mechanical impact. For melting or steelmaking, IFBs must always sit behind a dense working lining. Direct flame impingement on IFBs is acceptable in radiant heating but reduces life.

Which brand of IFB do you recommend?

For 1260–1430°C duty (most heat treatment work) we recommend Divine Cerawool IFBs, we are an authorised dealer and stock them in Delhi. For 1540–1760°C duty and tighter tolerances, CUMI Super Refractories IFBs are the standard choice. Both come with full ASTM C-155 documentation. We can sample a single carton for trial before bulk supply.

How are IFBs handled and installed?

Handle gently, IFBs have low crushing strength (0.5–5 MPa) so impact damage is easy. Use lightweight insulating mortar or a colloidal silica binder. Saw-cut to size with a masonry blade. Maintain joint thickness 2–3 mm. Dry-out schedule: ambient to 200°C at 10°C/hr, hold 4 hours, then ramp normally. Never expose unbacked IFBs to flowing molten metal.

Shaped Refractories 1850°C

INSULATING FIRE BRICKS (IFB)

Lightweight backup insulation reducing heat loss and energy bills

PRODUCT OVERVIEW

Insulating fire bricks (IFBs) are manufactured from refractory aggregates with carefully controlled porosity. Their low bulk density and low thermal conductivity make them ideal for backup linings and furnace insulation where minimising heat storage and heat loss is critical to energy efficiency. This range is supplied ex-CUMI under their CUMILAG (Porosint) brand name; the grade data below is CUMI's own published specification.

KEY PROPERTIES

Bulk Density

0.55 – 1.45 g/cc

Thermal Conductivity

0.14 – 1.43 W/mK (grade-dependent)

Max Service Temp

Up to 1850°C (bubble alumina grades)

Al₂O₃ Range

37% – 98.5%

Hot Face Capable

Yes — can be directly exposed to flame and combustion products

Base Materials

Calcined clay, calcined alumina, fused mullite, bubble alumina

APPLICATIONS

High-temperature kiln hot face & backup lining (ceramic, metallurgical)

General backup insulation behind a dense working lining

Primary reformer & hydrogen transfer line backup (fertiliser, petrochemical)

Secondary reformer cold face

Blast furnace stoves

High-temperature air pre-heaters (power generation)

Heat treatment furnace linings & soaking pits backup

TECHNICAL SPECIFICATIONS

Swipe table to see all columns

Grade	Al₂O₃	Bulk Density	Thermal Cond.	CCS	Max Temp
IFB-23	37.2%	0.55 g/cc	0.17 W/mK	1.2 MPa	1260°C
IFB-25	51.7%	0.80 g/cc	0.22 W/mK	2.5 MPa	1350°C
IFB-26	57.3%	0.86 g/cc	0.23 W/mK	1.8 MPa	1400°C
IFB-28	67.2%	0.88 g/cc	0.30 W/mK	2.5 MPa	1540°C
IFB-29	57.5%	1.05 g/cc	0.33 W/mK	3.9 MPa	1550°C
IFB-30	73.6%	1.12 g/cc	0.60 W/mK	4.9 MPa	1650°C
IFB-32	74.2%	1.28 g/cc	0.59 W/mK	4.9 MPa	1750°C
IFB-B201	91.1%	1.40 g/cc	1.38 W/mK	12.7 MPa	1800°C
IFB-B101	98.5%	1.45 g/cc	1.43 W/mK	7.4 MPa	1850°C

* Test conditions: IS 1528 (India) / ASTM C-133 / EN 1402. Values are typical, exact data sheets available on request.

AVAILABLE GRADES

IFB-23IFB-25IFB-26IFB-28IFB-29IFB-30IFB-32IFB-B201IFB-B101

INSTALLATION NOTES

1
Handle with care, lower crushing strength than dense bricks
2
Use lightweight insulating mortar matched to grade (e.g. CUMIBOND LK FX, LK 65, LM 36 or LA-series for CUMILAG grades)
3
Never expose directly to liquid metal or slag, always use with working lining
4
Dry-out schedule: ambient to 200°C at 10°C/hr, hold 4 hrs, then proceed slowly

WHY BUY FROM SHANKER AGENCIES

IFBs paired with a working lining can reduce furnace shell temperatures materially and cut fuel consumption versus an uninsulated dense lining. The IFB-23 to IFB-32 grades are calcined clay/alumina or fused mullite based (up to 1750°C); IFB-B201 and IFB-B101 are bubble alumina grades for the most demanding zones, up to 1850°C, including reformer radiant wall backup and blast furnace stove applications. Shanker Agencies engineers can calculate the optimal grade and lining thickness for your application, and can supply this range as CUMI's CUMILAG product line on request.

PARTNER BRANDS

CUMI Super Refractories (CUMILAG) Perfect Insulations

FREQUENTLY ASKED QUESTIONS

An IFB is a porous refractory brick, typically 40–80% porosity by volume, engineered for low thermal conductivity (0.15–0.35 W/mK) and low heat storage. A dense fireclay brick has 22–28% porosity and conducts heat 3–5 times faster. IFBs save energy and lower furnace shell temperatures, but cannot handle direct slag, metal or mechanical abuse like a dense brick can.

QUICK INFORMATION

Max Temperature

1850°C

READY TO ORDER OR NEED A SAMPLE?

Our engineers can recommend the exact grade for your application. Sample kits available for trials. No minimum order on standard grades.

Get a Quote Call +91 98999 57888

Available Grades, Insulating Fire Bricks (IFB)

Select a grade to see its full specification, designations and equivalents.

Need help selecting a grade? Send us your application, operating temperature, dimensions and specification requirements, and our technical team will review the requirement.

Send your requirement

Technical Data Sheet, Insulating Fire Bricks (IFB)

Shanker Agencies Pvt. Ltd. · Typical Values

Typical specification ranges with the applicable test standards. Compiled by Shanker Agencies for insulating fire bricks (ifb) supplied across India, GCC & ASEAN.

Typical Chemical Analysis

Property	Typical Value	Test Standard
Al₂O₃	45 – 65%	IS 1527
SiO₂	30 – 50%	IS 1527

Typical Physical Properties

Property	Typical Value	Test Standard
Bulk Density	0.5 – 1.1 g/cc	IS 1528 Pt-8 / ASTM C134
Thermal Conductivity	0.15 – 0.35 W/mK	ASTM C182
Cold Crushing Strength	1.0 – 5.0 MPa	IS 1528 Pt-4
Permanent Linear Change	< 1.5% at rated temp	IS 1528 Pt-6
Classification Temperature	1260 – 1650°C	ASTM C155 (Group 23–32)

Packaging & Supply: Standard IFB sizes (230×114×76 mm) and arch/wedge shapes; cartons or pallets.

Disclaimer: Values are typical and compiled by Shanker Agencies Pvt. Ltd. from standard industry data and published specifications of partner manufacturers (CUMI, Calderys, TRL Krosaki, Divine Cerawool, Crown Ceramics, Mahakoshal, Saint-Gobain). They are indicative and not a guarantee, confirm the exact grade datasheet before specifying. For a certified datasheet or quotation, contact info@shankeragencies.com or +91 98999 57888.