Shell-and-tube heat exchangers, also known as tube-and-shell heat exchangers, are indirect heat exchangers that use the wall surface of tube bundles enclosed in a shell as the heat transfer surface. This type of heat exchanger has a relatively simple structure, reliable operation, and can be manufactured using various structural materials (mainly metallic materials). It can be used under high temperature and high pressure conditions, making it the most widely used type of heat exchanger currently.
What are the key points to note when replacing the heat exchange tubes of shell-and-tube heat exchangers?
Let's learn about them together!
The surface of the heat exchange tube shall be free of defects such as cracks, folds, and laps.
When a heat exchange tube needs to be spliced:
- For a single heat exchange tube, only one weld is allowed (a U-tube can have two welds).
- The length of the short tube segment shall not be less than 300 mm, and the bent segment of the U-tube shall be at least 50 mm.
- There shall be no splice welds in the long straight tube segment.
- The misalignment at the joint shall not exceed 15% of the tube wall thickness, and shall not be greater than 0.5 mm.
When tube expansion is used for the connection between the heat exchange tube and the tubesheet:
- The hardness of the heat exchange tube shall be checked. Generally, the hardness of the tube shall be 30 HB lower than that of the tubesheet.
- If the hardness of the tube is higher than or close to that of the tubesheet, the two ends of the tube shall be subjected to annealing treatment. The annealing length shall be 80–100 mm longer than the thickness of the tubesheet.
The two ends of the heat exchange tube and the tubesheet holes shall be clean, free of contaminants such as grease, and shall not have defects that affect the tightness of the tube expansion (e.g., penetrating longitudinal or spiral scratches).
The two ends of the heat exchange tube shall protrude from the tubesheet, with a length of 4±1 mm.
Hydraulic expansion is recommended for the connection between the heat exchange tube and the shell-and-tube heat exchanger (manufactured in Shandong). Re-expansion of each expanded joint shall not exceed two times.
When welding is used for the connection between the heat exchange tube and the tubesheet:
- The cut surface of the tube shall be flat, free of burrs, unevenness, cracks, laminations, and other defects.
- The welding area shall be free of impurities that affect welding quality, such as slag, iron oxide, and oil stains.
In addition to shell-and-tube heat exchanger, GNEE also offers more high-quality products, such as volumetric heat exchangers, copper heat exchangers, titanium heat exchangers, heaters, chlorine coolers, high-pressure reactors, LPG storage tanks, cryogenic storage tanks, VPSA oxygen generators, etc. If you are interested in the above products or other products, please feel free to send an email to sales@gneeheatex.com, and our professional team will be happy to answer your questions.
Heat Exchanger Design Parameters
|
Shell side dimensions |
Value |
|
Shell internal diameter |
152 mm |
|
Shell wall thickness |
7 mm |
|
Shell material |
stainless steel,copper,titanium,carbon steel,etc. |
|
No. of Shell Pass |
1 |
|
No. of Baffles |
7, 9, 11, 13 |
|
Baffle plate thickness |
2 mm |
|
Tube side dimensions |
|
|
Tube internal diameter |
14 mm |
|
Tube wall thickness |
1 mm |
|
No. of Tube Pass |
1 |
|
No. of Tubes |
20 |
|
Tube Layout |
Square |
|
Tube Length |
1400 mm |
|
Tube material |
stainless steel,copper,titanium,carbon steel,etc. |