Lightweight clay insulating bricks are fireclay-based insulators in which graded fireclay grog is bonded around a controlled pore structure. They provide the outer insulation course of a refractory stack at the lowest material cost of any of the lightweight families on our line. XZK supplies the...
Lightweight clay insulating bricks are fireclay-based insulators in which graded fireclay grog is bonded around a controlled pore structure. They provide the outer insulation course of a refractory stack at the lowest material cost of any of the lightweight families on our line. XZK supplies the LC series in bulk densities from 0.6 to 1.3 g/cm3, with thermal conductivity from 0.25 to 0.55 W/(m·K) at 350°C and cold crushing strength from 1.5 to 8.0 MPa.
XZK Group produces grades XZK-LC135-1.3, LC135-1.0, LC125-0.8 and LC120-0.6 at our Xinmi plant in Henan. They close the insulation stack behind regenerator casings, breastwalls, suspended walls, forehearths and the doghouse, and they back the high alumina and mullite insulating courses where those take the higher temperature.
The raw material is fireclay, the same base material as an ordinary dense fireclay brick, but the body is built to a target density rather than to maximum density. Fireclay grog of a controlled grading supplies the refractory skeleton and the fired bond, while a pore-forming addition and a low forming pressure hold the structure open. The result is a brick that behaves like fireclay in service — it is chemically stable, dimensionally predictable and tolerates thermal cycling — but weighs a fifth to a half as much.
In the LC grade code, the trailing figure states the target bulk density in g/cm3, so LC135-1.3 is a 1.3 g/cm3 brick and LC120-0.6 is the lightest in the range. That direct naming is deliberate, because density is the number that governs both the insulation value and the strength of the brick, and the specification is easier to read and to check when it is written on the grade.
The justification for a fireclay insulator rather than an alumina one is economic rather than technical. In the outer courses of a furnace wall the temperature is low, the atmosphere is no longer aggressive, and nothing is in contact with the melt. An alumina body offers more refractoriness than that position needs and costs more to produce. Fireclay insulation performs the insulation duty at lower cost, and the money saved is better spent on the working course where the service conditions are severe.
The trade-off is the same density–conductivity–strength line that governs every insulating brick, and the LC range is wide enough to cover both ends. The 1.3 g/cm3 grade reaches 8.0 MPa and a conductivity of 0.55 W/(m·K); the 0.6 g/cm3 grade gives 1.5 MPa and 0.25 W/(m·K). A position that carries a load takes the dense grade; a position that only stops heat takes the light one.
| Technical Properties | XZK-LC135-1.3 | XZK-LC135-1.0 | XZK-LC125-0.8 | XZK-LC120-0.6 |
| Bulk Density (g/cm³) | ≤ 1.3 | ≤ 1.0 | ≤ 0.8 | ≤ 0.6 |
| Cold Crushing Strength (MPa) | ≥ 8.0 | ≥ 4.0 | ≥ 3.0 | ≥ 1.5 |
| Thermal Conductivity (350±25℃, W/(m·K)) | ≤ 0.55 | ≤ 0.40 | ≤ 0.35 | ≤ 0.25 |
Test methods follow GB/T and ISO practice; ASTM equivalents and full certificates of analysis are issued with every shipment.
Grade selection within the LC range is simpler than in a mixed family because the material is the same throughout and only density changes. Set the temperature the brick will see, set the load it will carry, and choose the lightest grade that meets both.
A practical rule is to reserve LC135-1.3 and LC135-1.0 for positions where the insulation course is load-bearing or where the wall must be structurally complete, and to use LC125-0.8 and LC120-0.6 purely as heat barriers where nothing bears on the brick.
Fireclay insulation is the economical outer layer of a furnace wall. It is placed where temperatures have already fallen and where the duty is purely thermal.
Clay insulating bricks are pressed from graded fireclay grog with a pore-forming addition, on the same automatic line that produces our dense fireclay and high alumina products. Four batching lines feed 20 CNC presses from 630 to 2000 tonnes, and press force is set per grade so that a 1.3 g/cm3 brick and a 0.6 g/cm3 brick are each brought to their own green density. Firing runs through four 108-metre fully automatic tunnel kilns and five ultra-high-temperature shuttle kilns, with a schedule slow enough to burn out the pore former without collapsing the pore structure.
Each batch is tested for bulk density, cold crushing strength and thermal conductivity at 350 ± 25°C, and permanent linear change is checked so that an insulation course does not shrink back from the working lining in service. A certificate of analysis accompanies every shipment. XZK Group holds ISO 9001, ISO 14001, ISO 45001 and ISO 50001 certification and operates the Henan Provincial Engineering Technology Research Center for Sintered Refractories for Glass Furnaces.
Clay insulating bricks close a stack that normally includes high alumina insulating bricks, mullite insulating bricks and alumina bubble bricks on the hotter side. The dense working courses they back are commonly low porosity fire clay bricks, high alumina bricks or andalusite bricks. For repairs and jointing, refractory mortar and ZKM series refractory mortar are matched to the same chemistry. See the insulating bricks range or browse all refractory products.
SiO₂:91%;
Bulk Density:0.8-1.2g/cm³;
Thermal Conductivity :0.26-0.35;
Al₂O₃:90-99%;
Bulk Density:1.35-1.70g/cm³;
Cold Crushing Strength:8-20MPa;
Al₂O₃:40-70%;
Bulk Density:0.60-1.10g/cm³;
Thermal Conductivity:0.20-0.60;
Al₂O₃:≥48%;
Bulk Density:0.6-1.2g/cm³;
Thermal Conductivity :0.25-0.50;
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