There are several methods for large cylinders to absorb thermal expansion

1. The support of the boiler drum and header is usually such that one end is fixedly supported while the other end is hingedly supported, in order to accommodate the expansion of the cylinder along its axis. At the hinged connection end, the contact surface must be smooth, and an expansion indicator device shall be installed. 2. For components subject to temperature rise, if their ends are fixed, the components themselves should have a structure that allows for expansion to be absorbed. For example, the furnace chamber of a horizontal shell-and-tube boiler should be equipped with expansion devices, or designed in a wavy shape ； All the heating surface tubes in water-tube boilers are made of bent tubes, giving them the ability to absorb thermal expansion ； Pipes for conveying steam and hot water should be equipped with expansion compensation mechanisms, such as elbow sections and expansion rings ； Corrugated expansion joints and similar devices should be installed on the flue. 3. An appropriate gap should be left at the expanded part of the component, and no other components or structures should be placed in this gap. 4. When a flat head or flat tube sheet is used to connect the furnace chamber or flue tubes, and if the flat plates are supported by struts, sufficient breathing space must be left on the plates surrounding the furnace chamber and flue tube bundles. In other words, the struts should be placed at a sufficient distance from the edges of the furnace chamber or flue tube bundles along the flat plates, so as to prevent restriction of the expansion and contraction of these components and avoid excessive thermal stress. The size of the breathing space around the furnace chamber on the plate is related to factors such as the plate thickness and the design of the furnace chamber ； The breathing clearance above and below the tube bundle area should be no less than 100 mm.