Which of the following materials is not suitable for a boiler's foundation?

The choice of wood as a foundation material for a boiler is not suitable due to several critical reasons. Boiling systems operate under extreme temperatures and pressure conditions, which can lead to significant structural demands on the foundation. Wood, being an organic material, is subject to decay, warping, and degradation over time, especially when exposed to high heat and moisture levels that may be present in boiler operations. These vulnerabilities compromise the stability and integrity of the boiler setup.

In contrast, steel, concrete, and brick are all durable and strong materials that provide the necessary support and stability for boiler foundations. Steel offers high tensile strength and is resistant to deformation, while concrete is robust, long-lasting, and can withstand heavy loads and harsh environmental conditions. Brick also provides good strength and durability, making these materials far more reliable for maintaining the boiler's structural integrity over time.