When is the removal of the back panel permitted after the completion of the panel?

The correct answer pertains to the standard practice regarding the timing for the removal of a back panel after its completion, which is crucial for maintaining the integrity of the refractory installation. The removal of the back panel is permitted after 18 hours, as this duration allows the refractory material to cure appropriately while minimizing the risk of damaging the panel or affecting its bonding strength.

Curing time is essential in refractory work because it ensures that the materials attain the necessary hardness and structural integrity before any handling or further assembly. Removing the panel too early could jeopardize the adhesion of the refractory and lead to potential failures in the installation. The specified 18-hour timeframe strikes a balance between allowing sufficient cure time and operational efficiency.

In refractories, precise adherence to these timing guidelines contributes significantly to the durability and performance of the refractory system, ensuring it meets operational requirements when back in service.