Insulation Bricks
Lightweight, low-thermal-conductivity refractory bricks engineered for backup lining and energy-efficient furnace design. Four grades from JM-23 to JM-30 — rated up to 1650°C with bulk densities as low as 0.80 g/cm³.
Available Grades & Specifications
Four grades covering the full insulation temperature range. All grades comply with ASTM C155 / GB/T 3995 insulating firebrick standards.
Low-Temperature Insulation Brick
JM-23 is the lightest and most insulating grade, rated to 1260°C (Class K-23). Its extremely low bulk density of 0.80 g/cm³ makes it ideal for the cold face and backup layers of ceramic kilns, heat treatment furnaces, and low-temperature industrial ovens where maximum insulation is the priority.
- Max service temperature 1260°C (ASTM Class K-23)
- Bulk density 0.80 g/cm³, thermal conductivity λ ≤ 0.35 W/m·K at 1000°C
- Highest insulation performance of the JM series
- For ceramic kiln cold faces, heat treatment furnace backup lining
Medium-Temperature Insulation Brick
JM-26 provides a balance of insulation performance and structural strength for medium-temperature applications up to 1430°C (Class K-26). Widely used in the backup lining of rotary kilns, continuous furnaces, and petrochemical reformer hot faces where shell temperatures must be controlled.
- Max service temperature 1430°C (ASTM Class K-26)
- Bulk density 1.00 g/cm³, thermal conductivity λ ≤ 0.45 W/m·K at 1200°C
- Balanced insulation and cold crushing strength ≥ 2.0 MPa
- For rotary kiln backup, tunnel kiln car decks, continuous furnaces
High-Temperature Insulation Brick
JM-28 extends insulation capabilities to 1540°C (Class K-28), making it appropriate as a backup layer behind high alumina bricks in cement kilns, glass furnace backup walls, and hot blast stove insulation shells. Good structural integrity for load-bearing backup applications.
- Max service temperature 1540°C (ASTM Class K-28)
- Bulk density 1.10 g/cm³, thermal conductivity λ ≤ 0.55 W/m·K at 1300°C
- Suitable as direct backup behind dense high alumina bricks
- For cement kiln backup, glass furnace insulation walls, steel plant soaking pits
Premium High-Temperature Insulation Brick
JM-30 is our highest-rated insulation brick at 1650°C (Class K-30). With higher mullite content providing superior hot strength and dimensional stability, it is used in the backup lining of the most demanding furnaces — including petrochemical cracking furnaces and high-purity kilns — where both insulation and structural integrity at extreme temperatures are required.
- Max service temperature 1650°C (ASTM Class K-30)
- Bulk density 1.20 g/cm³, thermal conductivity λ ≤ 0.65 W/m·K at 1400°C
- High mullite content ensures excellent dimensional stability at peak temperatures
- For petrochemical reformer backup, high-purity kiln walls, industrial furnace vaults
Technical Specifications
| Grade | Max Temp | Bulk Density | Cold CCS | λ at Peak Temp | ASTM Class |
|---|---|---|---|---|---|
| JM-23 | 1260°C | 0.80 g/cm³ | ≥ 1.5 MPa | ≤ 0.35 W/m·K | K-23 |
| JM-26 | 1430°C | 1.00 g/cm³ | ≥ 2.0 MPa | ≤ 0.45 W/m·K | K-26 |
| JM-28 | 1540°C | 1.10 g/cm³ | ≥ 2.5 MPa | ≤ 0.55 W/m·K | K-28 |
| JM-30 | 1650°C | 1.20 g/cm³ | ≥ 3.0 MPa | ≤ 0.65 W/m·K | K-30 |
Standard size: 230×114×65 mm. Custom sizes and shapes available. Thermal conductivity measured per ASTM C182.
Industry Applications
Insulation bricks reduce energy consumption by up to 30% versus solid dense brick linings — critical for all high-temperature industries.
Frequently Asked Questions
Higher grades (JM-28, JM-30) can be used as a single-layer hot face lining in lower-erosion environments like ceramic kilns and heat treatment furnaces. However, for environments with slag attack, abrasion (e.g. rotary kilns), or direct mechanical impact, pair insulation bricks as a backup layer behind a dense hot-face product such as high alumina bricks or castable to protect against premature erosion.
For the burning zone backup (behind magnesia or high alumina bricks), JM-28 or JM-30 is recommended due to the high interface temperatures. For the cooler end and transition zones, JM-26 provides adequate temperature resistance at a lower cost. Always calculate the cold-face temperature using the lining thermal model to confirm grade selection for your specific shell diameter and operating temperature.
Use a matching-grade insulation mortar — Firebrics supplies IM-12, IM-20, and IM-30 grades matched to the JM brick series. Insulation mortar maintains a low thermal conductivity at the joints, avoiding hot spots. For JM-23 and JM-26, IM-12 or IM-20 is appropriate. For JM-28 and JM-30, use IM-30. Apply as a 2–3 mm thin set.
Related Products
High Alumina Brick
Dense hot-face brick paired with insulation bricks in multilayer lining systems.
Insulation Mortar
Low-conductivity mortar for insulation brick joints — prevents thermal bridging.
Conventional Castable
Cast insulating refractory for irregular shapes where brick laying is impractical.
Get a Quote for Insulation Bricks
Provide your required grade (JM-23 to JM-30), dimensions, and annual quantity. We'll confirm pricing, lead time, and technical recommendations within 24 hours.