Stay bolts are typically used in which type of boiler?

Stay bolts are integral components typically used in fire tube boilers. These bolts provide structural support and stability to the boiler shell, which is essential for maintaining its integrity under the pressure developed during operation. The design of fire tube boilers, where the hot gases from combustion travel through tubes that are surrounded by water, necessitates a method to support the cylindrical shape of the boiler to withstand the internal pressure and thermal stresses.

Stay bolts are specifically designed to resist compression and help distribute the load evenly across the boiler structure. In contrast, water tube boilers utilize a different design where water flows through tubes and the combustion gas surrounds them. This difference in design and construction leads to varying requirements for structural support. Electric and combined cycle boilers have entirely different configurations that do not utilize stay bolts in the same manner as fire tube boilers. Therefore, the use of stay bolts is predominately associated with fire tube boilers, making that the correct answer.