In SW6, what is the difference between 【expansion jointing】 and 【strength expansion jointing】 in terms of the way the heat exchange tubes are connected to the tube sheet?

In the design and manufacturing of heat exchangers, the way in which the tube sheet is connected to the tubes has a significant impact on the overall strength, sealing performance, and corrosion resistance of the equipment. The following is a brief explanation of the several connection methods you mentioned: 1. **Expansion Joint**: This is a common method for connecting pipes to tube sheets. The ends of the tubes are expanded mechanically to fit tightly against the wall of the tube sheet hole, thereby creating a sealed connection. Expansion joining is usually carried out using an expansion tube machine, and it can achieve a good sealing effect; however, its main function is not to withstand pressure but rather to position and seal. 2. **Strength Roll**: As the name suggests, in addition to providing sealing, the Strength Roll also increases the mechanical strength of the joint, enabling the connection between the tube and the tube sheet to withstand higher pressures. In certain application scenarios, to ensure safety and durability, additional strength is required to resist various forces during operation. 3. **Strength Roll plus Seal Welding**: This method combines strength rolling with welding; it first uses strength rolling to pre-fix and enhance the strength of the connection between the tube and the tube sheet, and then performs a seal weld at the connection point in order to achieve higher sealing performance and strength. This method is used in situations with extremely strict requirements, such as high-pressure, high-temperature, or highly corrosive environments. 4. **Grooved Expansion Joint**: One or more annular grooves are created inside the tube holes of the tube sheet, and then the tubes are fixed to the tube sheet using expansion jointing. This method also increases the contact area between the tube and the tube sheet, thereby enhancing the strength and sealing performance of the connection. 5. **Welding**: The simple welding method involves directly welding the ends of the tubes to the holes in the tube sheet. The advantage of this connection method is its high strength and good sealing performance, but the downside is that replacing the pipe requires a considerable amount of work. Welding is generally suitable for applications where heat exchange tubes do not need to be replaced frequently. The above is a basic introduction to several different methods of connecting pipes to tube sheets; the specific method to be used depends on the design requirements and operating conditions of the heat exchanger. When making a practical choice, factors such as the operating pressure and temperature of the equipment, the corrosiveness of the medium, and the manufacturing and maintenance costs need to be considered. I hope this information is helpful to you. .

As shown in this diagram, in SW6, should one choose “intensity expansion sealing welding” or “welding”? Or should I choose “seamless expansion joint”?

Based on the description of the drawing number “3370052” you provided and the standard design criteria for heat exchangers, if the drawing in question shows the way in which the tubes are connected to the tube sheet, we need to see the image itself in order to determine what type of connection is used. However, I can provide you with some general guidance based on the description: – If there is both expansion bonding and welding between the pipe end and the tube sheet (that is, the pipe is first fixed to the tube sheet by mechanical expansion bonding, and then sealed by welding around it), then this type of connection should be designated as “strength expansion bonding with sealing welding”. In SW6 (or similar software), this approach provides good mechanical strength and sealing properties, and is generally used in environments with high pressures and temperatures. - If the tube is connected to the tube sheet only by welding, without any expansion bonding process, that is, if the tube is welded directly to the tube sheet without any other mechanical fixation methods, then “Welding” should be selected. - If the pipe is expanded but not grooved, that is, the pipe ends are not welded; instead, mechanical methods are used to ensure a tight fit between the pipe and the socket in order to achieve positioning and sealing, then this method is called \"ungrooved expansion fitting\". The actual choice needs to be determined based on specific design drawings and technical requirements. It is recommended that you refer to the specific heat exchanger design specifications or consult a professional heat exchanger design engineer to determine the most suitable connection method. .

This post was last edited by wanlirn on 2023-11-16 08:02. This is the welding method; expansion fitting does not provide sufficient strength. Most media have a tendency to suffer from crevice corrosion, including common cooling water. Additionally, vibration of the heat exchange tubes is inevitable, and reducing the gaps can lessen the impact of vibration on the welds. Therefore, in engineering practice, heat exchange tubes are often welded with high strength and combined with expansion fittings.

I think the other ones can be understood from their literal meanings, and there’s also a diagram on page 151 – it’s the one without grooves. It’s used for small-diameter heat exchange tubes with a diameter of 12 mm or less; such tubes can be joined by expansion fitting without the need for grooves, but it’s necessary to first bend the tube ends

“For \"strength expansion sealing welding\" and \"notched expansion joining\", the pull-out force is the same (in terms of calculation), but the expansion length differs (in terms of manufacturing; however, this should not affect the calculations). For details on the expansion length, see 151

I learned from the comments. There’s also a question regarding the manufacturing process: if strength is increased by grooving followed by welding, should welding be done first or grooving first? Or is either order acceptable?