How are firetube boiler tubes secured into flat steel plates?

In a firetube boiler, tubes are secured into flat steel plates called tube sheets. Tube sheets serve as critical components that provide a boundary for the boiler's combustion gases and water. The fire tubes penetrate these flat plates, forming a direct connection between the tube and the boiler’s shell or drums. This connection is essential for maintaining the integrity of the boiler, as it helps contain the pressure and prevent leaks.

The tube sheets are designed with precision to accommodate the tubes, ensuring a tight fit that allows for efficient heat transfer while also providing structural support. The arrangement of the tubes within the tube sheets is crucial for the efficiency and safety of the boiler operation. Properly secured tubes prevent any movement that could lead to wear or failure, thereby maintaining operational reliability.

While shells, drums, and headers are important components of a firetube boiler system, they do not serve the specific function of securing the tubes as the tube sheets do. Shells and drums house the entire boiler assembly, while headers serve to distribute water or steam to and from the tubes, but neither provides the direct structural connection of the tubes to the boiler body like tube sheets do.