Free Plant Design and Economics MCQs with Answers

• A. 1520
• B. 1630
• C. 1670
• D. 1730

Explanation: A Seger cone above cone 33 corresponds approximately to 1730°C. PCE is a heat-resistance measurement based on the softening and bending of…

• A. Crucibles used for melting of high purity metals
• B. Muffles for muffle furnaces
• C. Insulating bricks
• D. Segar cones

Explanation: Thoria is costly and radioactive, but its very high melting point and chemical stability allow it to be used in crucibles for melting…

• A. 450
• B. 250
• C. 150
• D. 65

Explanation: At high temperature, fireclay brick loses much of its cold crushing strength because its structure softens and undergoes mineral…

• A. Mullite
• B. Silica
• C. High duty fireclay
• D. Carborundum

Explanation: High-duty fireclay bricks are commonly used for the walls, roofs, and combustion chambers of annealing furnaces because they tolerate high…

• A. May increase or decrease; depends on its alumina content
• B. Decreases
• C. Remain constant
• D. Increases

Explanation: Increasing alumina content generally raises the refractoriness and fusion point of alumina-silica refractories.

• A. Fusion point
• B. Spalling resistance
• C. Resistance to slag penetration
• D. Resistance to carbon monoxide attack

Explanation: PCE indicates the temperature at which a refractory cone softens and bends under its own weight, so it is used as an empirical measure of…

• A. Obtaining monolithic working faces
• B. Both A. & B.
• C. Repairing construction of various furnace parts
• D. Neither A. nor B.

Explanation: Ramming masses are placed and compacted to form monolithic furnace linings or working faces, and they are also used for repairing worn…

• A. Resistance to slag
• B. Refractoriness
• C. Crushing strength
• D. Spalling resistance

Explanation: Magnesite helps chrome-magnesite refractories withstand sudden temperature changes, so its principal benefit is improved thermal-spalling…

• A. Fireclay bricks
• B. Tar bonded dolomite bricks
• C. Magnesite bricks
• D. Chromite bricks

Explanation: Fireclay contains a relatively high proportion of plastic clay, which loses water and contracts substantially during drying.

• A. Mullite
• B. Dolomite
• C. Bauxite
• D. Corundum

Explanation: Mullite, corundum, and bauxite are alumina-rich refractory materials. Dolomite is mainly calcium and magnesium carbonate, converted to…

• A. Mainly contains quartz
• B. Is not stable at high temperature
• C. Transforms to other allotropic forms i.e. Tridymite and Cristobalite involving very high
• D. All A., B. and C.
• E. volume changes

Explanation: Natural silica is chiefly quartz, but quartz is not the stable high-temperature form.

• A. 500
• B. 1000
• C. >2000
• D. >1350

Explanation: Fireclay bricks normally retain their shape under a 2 kg/cm² load until temperatures above about 1350°C, although the exact value depends…

• A. 200-400
• B. 100-150
• C. 50-100
• D. 500-1000

Explanation: Fireclay bricks generally have a cold crushing strength of about 200–400 kgf/cm².

• A. Basic Bessemer converter
• B. All A., B. and C.
• C. Electric furnaces
• D. Basic open hearth furnace

Explanation: Tar dolomite bricks resist basic slags and are used in basic Bessemer converters, basic open-hearth furnaces, and electric furnaces.

• A. Fireclay
• B. Silica
• C. Chrome magnesite
• D. None of these

Explanation: Chrome magnesite is a basic refractory because its principal constituents, magnesia and chromite, resist attack by basic slags.

• A. Attack by basic slag
• B. Abrasion
• C. Disintegration on sudden change of temperature
• D. Both B. and C.

Explanation: Magnesite refractories resist basic slag well, but they have poor resistance to abrasion and thermal shock, causing disintegration during…

• A. High co-efficient of expansion upto this temperature
• B. Very high thermal conductivity
• C. High thermal diffusivity
• D. Low refractoriness

Explanation: Silica undergoes marked thermal expansion and structural changes below about 600°C, producing internal stresses and poor spalling…

• A. CaO
• B. MgO
• C. Al2O3
• D. SiO2

Explanation: Periclase is essentially crystalline magnesium oxide, MgO, obtained from magnesite or other magnesium-bearing materials.

• A. Very high temperatures are involved
• B. Highly reducing conditions are involved
• C. All A., B. and C.
• D. Presence of iron or silica is harmful

Explanation: High-purity alumina fused-mullite linings are selected for very high temperatures, reducing atmospheres, and service where iron or silica…

• A. Castables
• B. Cements
• C. Mortars
• D. None of these

Explanation: Castables are dry mixtures of refractory aggregates and hydraulic or other bonding materials that are mixed with water and cast into…