The connection between the seal gasket (II) and heat exchange pipe of Shandong heat exchanger is generally circular plate, which is provided with holes and heat exchange pipes. In the multi tube heat exchanger, the split partition plate is also set on the tube plate. The tube plate also separates the space between the tube and shell side, avoiding the mixing of cold and hot fluids. Expansion, welding or joint between tube plate and heat exchange pipe can be adopted. The expansion connection between tube plate and heat exchanger pipe is to make use of the poor hardness between pipe and tube plate material (when selecting materials, the hardness of tube plate material is higher than that of pipe material), so that the diameter of pipe under the action of tube expander is expanded and plastic deformation occurs. The tube plate only produces elastic deformation. After expanding, the tube plate is tightly connected with the outer surface of the pipe under the action of elastic recovery force, Achieve the purpose of sealing and fastening the connection, as shown. The expansion connection structure is simple and easy to replace and repair the pipe, but it is not suitable for working at high temperature and high pressure. With the increase of temperature and pressure, the sealing and firmness of expansion joint will gradually decrease the seal gasket of Shandong heat exchanger. Welding connection is to weld the end of heat exchange pipe with the tube plate. The connection is simple and not limited by the hardness of pipe and tube plate material, and it can still maintain good sealing and firmness under high temperature and high pressure. Therefore, welding connection is used in high temperature, high pressure and even some occasions where the pressure is not too high, as shown in the figure. The disadvantage of welding connection is that the pipe end is welded to the tube plate, while the outer wall of most pipe sections along the thickness direction of the tube plate has a circular gap with the tube plate. In these gaps, the fluid does not flow and is prone to "clearance corrosion". In order to eliminate the gap, Shandong heat exchanger gasket can be expanded and welded and connected（ 3） The shell and tube plate connection  the shell of the shell type heat exchanger is cylindrical, and the smaller diameter is made of seamless steel pipe, and the larger diameter is made of steel plate rolling and welding; The materials and requirements of the shell are the same as those of the general pressure vessels. The connection between shell and tube plate of different types of tube and shell heat exchanger is different. In fixed tube plate heat exchanger, both ends of tube plate are welded with shell, which is called the non detachable connection between tube plate and shell; According to whether the pipe plate is used as flange, the structure of the flange is not used. As shown in the figure, the pipe plate is used as the flange structure in most cases. The tube plate and shell fixed end in floating head and U-tube heat exchanger are connected with the shell by detachable connection, and the tube plate is clamped between the shell flange and the tube box flange, so that the tube bundle can be removed from the shell for cleaning and maintenance, as shown in the figure（ 4） The function of the tube box is to distribute the fluid entering the pipe side evenly to each heat exchanger gasket of Shandong heat exchanger, and to gather the fluid in the pipe to send it out of the heat exchanger. In the multi tube heat exchanger, the tube box can also be separated by setting the diaphragm. The structure of the pipe box is shown in the figure, and Fig. (a) is suitable for cleaner medium. It is not convenient to remove the tube box as a whole when checking the pipe and cleaning; Fig. (b) the flat cover is installed on the pipe box. As long as the flat cover is removed, it can be cleaned and inspected. Therefore, there are many engineering applications, but the material consumption is too much; Fig. (c) the pipe box is welded with the seal pad tube plate of Shandong heat exchanger. The structure has good sealing property, but the tube box can not be removed separately, so it is not convenient to overhaul and clean, and the practical application is less（ 5） The baffle plate is a bow or disc ring plate set vertically with the tube bundle in the shell, as shown in the figure.