Heat exchangers serve as core heat transfer equipment in petrochemical, power, metallurgical and other industries. As their key component, tube bundles operate continuously under high temperature, high pressure and corrosive media, and are prone to scaling, leakage, abrasion and other faults, which directly impair heat transfer efficiency and production safety. When a damaged tube bundle cannot be repaired, timely replacement becomes an essential measure to ensure stable equipment operation. This article provides a detailed full-process analysis of heat exchanger tube bundle replacement, covering preliminary preparation, old tube bundle removal, new tube bundle installation, commissioning and acceptance, as well as safety precautions, so as to offer comprehensive practical guidance for industrial operation.
Preliminary preparation lays the foundation for tube bundle replacement and directly determines construction efficiency and overall quality. It mainly consists of three key stages: equipment shutdown and isolation, technical preparation, and material preparation.
First, complete equipment shutdown and safety isolation. A targeted shutdown plan shall be formulated in advance to gradually cut off feeding and discharging of the heat exchanger. Inlet and outlet valves shall be closed with blind plates installed to completely disconnect the equipment from the process system and prevent medium leakage and safety hazards. Afterwards, the internal cavity of the heat exchanger shall be purged, cleaned and medium-displaced to remove residual fluid, scale and debris and reduce operational risks. Meanwhile, internal corrosion, deformation and other defects of the shell shall be inspected and recorded.
In terms of technical preparation, core parameters including heat exchanger model and tube bundle specifications must be verified strictly to ensure perfect matching between the new tube bundle and the shell, which is critical for smooth subsequent installation.
Four key specifications of the tube bundle shall be strictly checked:
Length: It shall precisely match the shell length, with reasonable assembly clearance reserved according to tubesheet thickness. The overall deviation shall be controlled within ±3 mm. Excessively long bundles will fail to fit into the shell, while overly short ones will cause sealing failure on the tubesheet.
Tube diameter: It shall be accurately matched with the holes on the tubesheet. Common specifications include φ19 mm, φ25 mm and φ38 mm, determined by heat exchange area requirements and medium flow velocity. The diameter deviation shall not exceed ±0.5 mm to avoid medium leakage caused by excessive gaps or installation difficulties due to undersized clearances.
Wall thickness: Calculated and selected based on operating pressure and medium corrosiveness. The wall thickness of general industrial tube bundles ranges from 1.5 mm to 3.5 mm, while thicker-walled tubes are required for high-pressure working conditions. Uniform wall thickness shall be inspected to prevent local weakness and structural damage.
Material: Selected according to medium characteristics and operating temperature. 20# carbon steel is applicable for weakly corrosive media such as water and steam; 304 or 316L stainless steel is adopted for acid, alkali and salt solutions with strong corrosiveness; special materials such as titanium alloy and Hastelloy are used for high-temperature, high-pressure and strongly corrosive working conditions, such as sulfur-containing chemical media. Material certificates must be provided for verification to eliminate premature corrosion and damage caused by unqualified materials.
The removal of the old tube bundle shall follow the principle of auxiliary components first, main structure later. External accessories shall be dismantled and clearly marked, followed by the disconnection between the tube bundle and the tubesheet to prevent tubesheet damage. The old tube bundle shall be lifted out symmetrically by crane. The inner shell shall be thoroughly cleaned, and tubesheets and baffles shall be inspected and repaired timely if any defects are found.
The installation of the new tube bundle shall comply with strict technical standards. The appearance of the new tube bundle shall be inspected comprehensively, followed by derusting, cleaning and anti-corrosion coating treatment. Worn sealing parts shall be replaced in advance. The tube bundle shall be slowly hoisted into the shell with concentricity adjusted accurately. Tube expansion or welding construction shall be completed in accordance with specifications. Finally, auxiliary components shall be reinstalled and all connecting bolts fully tightened.
Commissioning and acceptance are the final critical steps. A full inspection of all components shall be carried out before commissioning. Hydrostatic testing shall be conducted at 1.25 to 1.5 times the design pressure. For heat exchangers serving gaseous media, additional air tightness testing is mandatory. After passing all tests, load commissioning can be implemented. The equipment can be officially put into service when all operating parameters meet standards and operation remains stable.
The above introduces the complete operation process of heat exchanger tube bundle replacement.
Shanghai Rivbay Chemical Equipment Co., Ltd. specializes in the research, development and production of non-standard pressure vessels, including reaction kettles, heat exchangers, stainless steel reaction kettles, tower vessels, modular equipment, freeze dryers and cold traps. The company holds ASME U Stamp Certification, EU PED Certification, Korea Kosha Certification and EAC Certification of the Eurasian Economic Union. Its products are widely applied in chemical, petrochemical, fine chemical, pharmaceutical, food, light industry, environmental protection and other industries. We can customize highly adapted professional equipment solutions for different working conditions. Customers are welcome to contact us for inquiries and cooperation.
