Points for Attention in the Replacement of Heat Exchange Tubes of Shell and Tube Heat

Points for Attention in the Replacement of Heat Exchange Tubes of Shell and Tube Heat Exchangers

Shell and tube heat exchanger (shell and tube heat exchanger) is also called shell and tube heat exchanger. It is a partition type heat exchanger with the wall surface of the tube bundle enclosed in the shell as the heat transfer surface. This kind of heat exchanger has a relatively simple structure and reliable operation. It can be made of various structural materials (mainly metal materials) and can be used under high temperature and high pressure. It is a type with wide application at present.

　　 Shell and tube heat exchanger heat exchange tube replacement points to note:

　　 1. The surface of the pipe should be free of defects such as cracks, folds, and heavy leather.

　　2. When the tubes need to be spliced, the same heat exchange tube can only have one weld at most (the U-shaped tube can have two welds). The shortest pipe length shall not be less than 300mm, and the U-shaped pipe elbow section shall be at least 50mm, there shall be no splicing welds in the long straight pipe section, and the amount of misalignment shall not exceed 15% of the pipe wall thickness and shall not exceed 0.5mm.

　　3. The hardness of the tube should be checked when the tube and tube sheet are expanded. Generally, the hardness of the tube is required to be 30HB lower than that of the tube sheet. When the hardness of the tube is higher than or close to the hardness of the tube sheet, the two ends of the tube should be annealed, and the annealing length is 80-100mm longer than the thickness of the tube sheet.

　　4. Both ends of the pipe and the tube plate holes should be clean, free of grease and other dirt, and there should be no penetrating longitudinal or spiral nicks that affect the tightness of the expansion.

　　 5. Both ends of the tube should extend out of the tube plate, and its length is 4±1mm.

　　6. ​​Hydraulic expansion should be adopted for the expansion of pipe and tube sheet. Each bulging mouth should not be reinflated more than twice.

　　7. When the pipe and the tube sheet are welded, the cut surface of the pipe should be flat, free of burrs, bumps, cracks, interlayers, etc., and there should be no slag, iron oxide, grease and other debris that affect the welding quality.