1.1 This specification covers one type of thermal insulating brick for use as backup insulation for refractory furnace linings of boiler furnaces.1.2 The values stated in inch-pound units are to be regarded as standard. The SI units in parenthes This specification covers thermal insulating bricks made from fire clay that are used as backup insulation for refractory furnace linings of boiler furnaces. The bricks shall be composed of heat-resistant materials that have been burned or fired to pro