Fire Clay Refractory Bricks (Fireclay Brick) for Furnaces

Fire clay bricks handle the moderate-heat duty that makes up most of a furnace. They form and repair chimney stacks, oven and kiln walls, boiler settings, flue ducts, hearths and the backup layers that sit behind a hotter working lining, in everything from a brick oven to an industrial kiln. They give sustained heat resistance at a fraction of a high alumina brick's cost, which is why they are the default wherever the temperature is not extreme.

Low porosity means the brick has fewer and smaller open pores — a tighter, denser body. It matters because open pores are the route by which slag, molten glass, gas and moisture get in and attack a brick from within; a low-porosity fireclay brick soaks up less of them, resists spalling and flaking, and so keeps its strength and lasts longer. It is what separates a quality fire clay brick from a cheap, coarse one.

Fire clay bricks carry roughly 30 to 45 percent alumina, the rest mostly silica, which places them in the economical, general-purpose class and gives a refractoriness of SK-30 to SK-35 — enough for the many furnace zones below the extremes. Push the alumina higher and the brick becomes a high alumina brick, with greater refractoriness and hot strength, which we offer as its own grade.

Step up to high alumina once a position runs too hot, bears too much load, or faces too much slag or melt for a clay brick. Fireclay is the economical answer for warm and backup zones; the searing cores, heavily loaded arches and surfaces bathed in slag or molten glass want the higher refractoriness and hot strength of high alumina. Send us the furnace type and its working temperature and we will mark where fireclay ends and high alumina should begin.

The stock item is a 230 by 114 by 65 millimetre straight, and beyond it we carry the usual refractory shapes and cut specials from your drawing — wedges, arches, keys and skews for building arches, walls and flue work. Send the drawing or a shape list with quantities, and the grade, shapes and price come back together.