Refractoriness under load (RUL) for fireclay bricks under a load of about 2 kg/cm² is typically at what temperature?

Introduction / Context:
RUL indicates the temperature at which a refractory deforms under a specified mechanical load. It is a more realistic indicator of service capability than fusion temperature alone because load-bearing structures must resist creep and softening.

Given Data / Assumptions:

• Material: typical dense fireclay brick.
• Load: around 2 kg/cm² (a standard test condition).
• We seek the characteristic temperature threshold.

Concept / Approach:
For standard fireclay bricks, RUL values usually exceed 1350 °C under the given load, depending on alumina content and glassy phases. Values far below 1000 °C would indicate very poor hot strength, whereas > 2000 °C is unrealistic for fireclay compositions.

Step-by-Step Solution:
Recall typical RUL band for fireclay: above 1350 °C at moderate load.Eliminate very low or unrealistically high temperatures.Select “> 1350 °C.”

Verification / Alternative check:
Datasheets for super-duty and high-duty fireclay list RUL values in the mid-1300s to 1400+ °C under standard loads.

Why Other Options Are Wrong:
500–1000 °C: too low for sound fireclay bricks.> 2000 °C: beyond fireclay capability.

Common Pitfalls:
Confusing PCE with RUL; they are related but not identical.

Final Answer:
> 1350 °C