Refractory Glossary
Short definitions of the terms that appear on refractory data sheets, quotations and lining drawings, with the standard test method where one applies.
A
- Abrasion resistance
- How well a refractory resists being worn away by moving solids, such as clinker, catalyst or burden material. It is reported as the volume of material lost in a standard blast test, so a lower number is better.Test method: ASTM C704
- Acid proof brick
- A dense, low-absorption ceramic brick made to resist chemical attack rather than heat. It is laid with a chemical-resistant mortar over a membrane to line tanks, floors and drains in chemical plants.Test method: IS 4860Read more about acid proof brick
- Anchor
- A metal or ceramic fastener fixed to the furnace shell that holds a castable, gunned or fibre lining in place. The anchor material and spacing are chosen for the lining thickness and temperature.Read more about anchor
- Apparent porosity
- The share of a brick or castable volume made up of open pores that liquid or gas can enter, given as a percentage. Lower porosity usually means better resistance to slag and metal penetration.Test method: ASTM C20; IS 1528
B
- Backup lining (safety lining)
- The layer behind the working lining. It insulates the shell and holds the vessel safely if the working lining wears through.
- Basic refractory
- A refractory based on magnesia (MgO) or dolomite. It resists basic slags, which is why it is used in steelmaking vessels and cement kiln burning zones.Read more about basic refractory
- Bulk density
- The mass of a refractory divided by its total volume, pores included. It is used to work out lining weight and is a quick check on how well a brick was pressed or a castable was installed.Test method: ASTM C20; IS 1528
C
- Campaign life
- How long a lining lasts between relines. It is counted in heats for ladles and furnaces, and in months or years for kilns and glass tanks.
- Castable
- A dry mix of refractory aggregate and binder that is mixed with water and cast, vibrated or pumped into place like concrete. It forms a jointless lining and suits complex shapes.Read more about castable
- Ceramic fibre
- A lightweight alumino-silicate fibre insulation supplied as blanket, board, module, paper or rope. It stores very little heat, so it suits furnaces that heat and cool often.Read more about ceramic fibre
- Cold crushing strength (CCS)
- The compressive load a refractory can take at room temperature before it fails. It shows handling and load-bearing strength, not how the material behaves at furnace temperature.Test method: ASTM C133; IS 1528
- Creep
- Slow, permanent deformation of a refractory under a steady load at high temperature over time. It matters for tall structures that carry load for years, such as hot blast stoves and glass tank crowns.Test method: ASTM C832
D
- Dry-out
- The controlled first heating of a new castable or gunned lining to remove water before it goes into service. Heating too fast can turn trapped water to steam and burst the lining.
F
- Fireclay brick
- An alumino-silicate brick made mainly from fireclay. Under IS 4041 it contains 30% to less than 45% alumina. It is the general-purpose brick for boilers, kiln cars and backup linings.Test method: IS 8; IS 4041Read more about fireclay brick
G
- Gunning mix
- A refractory mix sprayed onto a surface through a nozzle with compressed air. It is used to repair worn areas quickly, often while the vessel is still hot.Read more about gunning mix
H
- High alumina brick
- An alumino-silicate brick with 45% alumina or more under IS 4041. Higher alumina generally gives higher service temperature and better slag resistance.Test method: IS 4041Read more about high alumina brick
- Hot modulus of rupture (HMOR)
- The bending strength of a refractory measured at high temperature. It shows whether the material stays strong at service temperature, which room-temperature strength cannot show.Test method: ASTM C583
I
- Insulating fire brick (IFB)
- A lightweight, porous brick with low thermal conductivity, used behind a dense lining or as a hot face in clean atmospheres. The grade number is a temperature class, not the alumina content.Read more about insulating fire brick
L
- Low cement castable (LCC)
- A castable with a much lower cement content than a conventional castable. It needs less water, so it sets denser and stronger, but it must be mixed and dried out with more care.Read more about low cement castable
M
- Material test certificate (MTC)
- A document from the manufacturer that states the tested properties of the batch supplied. Buyers use it to check a consignment against the specification.
- Monolithic refractory
- Any refractory installed without joints, as opposed to bricks. Castables, gunning mixes, ramming masses and plastics are all monolithics. Also called unshaped refractory.Read more about monolithic refractory
- Mortar
- A fine refractory material used to bed and joint bricks. It should match the chemistry of the brick it joins.Read more about mortar
P
- Permanent linear change (PLC)
- The lasting shrinkage or expansion of a refractory after it has been heated to a set temperature and cooled. A large change can open joints or build stress in the lining.Test method: ASTM C113; IS 1528
- Pyrometric cone equivalent (PCE)
- A measure of refractoriness. A test cone made from the material is heated beside standard cones, and the result is the number of the standard cone that softens and bends at the same time.Test method: ASTM C24; IS 1528
R
- Ramming mass
- A dry or semi-dry granular refractory that is compacted in place and then sintered by the first heats. It forms the working lining of coreless induction furnaces.Read more about ramming mass
- Refractoriness under load (RUL)
- The temperature at which a refractory begins to deform while it carries a fixed load. It is a better guide to the safe working temperature of a loaded lining than PCE.Test method: ISO 1893; IS 1528
- Refractory
- A material that keeps its strength and shape at high temperature and resists heat, chemical attack and wear. Refractories line furnaces, kilns, ladles, boilers and reactors.
S
- Shaped refractory
- A refractory formed and usually fired before delivery, such as bricks and special shapes. It is laid with mortar on site.Read more about shaped refractory
- Sintering
- Heating a compacted refractory until its grains bond into a hard mass without fully melting. In an induction furnace, the first heats sinter the ramming mass into a working lining.
- Slag line
- The band of a ladle or furnace lining in contact with molten slag. It usually wears fastest and often decides when the vessel is relined.Read more about slag line
T
- Thermal conductivity
- How readily heat passes through a material. Insulating products have low conductivity. It changes with temperature, so it is always quoted at a stated mean temperature.Test method: ASTM C201
- Thermal shock resistance
- The ability of a refractory to survive rapid temperature change without cracking or spalling. It matters wherever a lining is heated and cooled in cycles.Test method: ASTM C1171
U
- Ultra low cement castable (ULCC)
- A castable with even less cement than a low cement castable. It gives very high strength and good hot properties, and it is sensitive to water addition and dry-out.Read more about ultra low cement castable
W
- Working lining
- The layer of the lining that faces the heat, metal, slag or process gas. It is the layer that wears and is replaced.
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