Heat exchanger expansion tube

There are mainly two methods for expansion jointing of heat exchange tubes: mechanical and hydraulic. Mechanical expansion joining is currently the most widely used method both domestically and internationally. In addition to disadvantages such as high labor intensity and low work efficiency, this method also makes it difficult to perform full-thickness expansion bonding on heat exchangers with a tube sheet thickness of over 100 millimeters. Modern chemical plants operate under high parameters, which results in increasingly thicker tube sheet thicknesses in heat exchangers. Heat exchangers with tube sheet thicknesses exceeding 200 millimeters are now common, and traditional mechanical expansion joining techniques can no longer be used to expand such thick tube sheets throughout their entire thickness. As a result, it is difficult to eliminate the gap between the heat exchange tubes and the tube sheet, creating a risk of gap corrosion. Hydraulic expansion joining is a new type of expansion joining technology that has been developed in recent decades. It includes two methods. One is the “O-ring” method, which uses an O-ring as the sealing element and requires high precision and low roughness in the dimensions of the inner wall of the tube. Another is the liquid-bag hydraulic expansion joining technique, which can perform reliable full-length expansion joining on heat exchange tubes of various specifications and materials. It is particularly suitable for expansion bonding of thick tube sheet heat exchangers and large-diameter tubes. The liquid-bag type hydraulic tube expansion machine is a specialized expansion device used in the manufacturing and maintenance of heat exchangers and boilers to connect tubes to tube sheets. The liquid bag type hydraulic tube expansion technology has the following features: 1. Low labor intensity and high production efficiency ； 2. The expansion joint quality is uniform and reliable ； 3. The tube expansion medium does not contaminate the joint ； 4. Low residual stress in the tube after expansion ； 5. Low requirements for the dimensional accuracy of the heat exchange tubes ； 6. Full expansion bonding can be performed on heat exchangers with any tube sheet thickness.

It is determined by the materials of the heat exchange tubes and the tube sheet; different heat exchange tubes have different processing requirements, which lead to an increased need for strong sealing.

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The explanation on the 3rd floor was very detailed. Generally, we use tube expanders for expanding tubes, though this decision also depends on the material of the heat exchange tubes as well as the conditions at the site.

It is very convenient to use a tube expander these days. Hydraulic tube expansion technology: 1. It allows for the expansion of tube sheets of any thickness and heat exchange tubes of any length in just one operation. 2. It results in minimal work hardening; even materials that are difficult to expand mechanically, such as titanium or duplex steel, can be expanded easily. 3. It ensures a small reduction in tube wall thickness and stress concentration from the expanded area to the unexpanded area, thereby extending the service life of the heat exchange tubes. 4. It improves the quality of expansion, as each expansion process is controlled by the parameters of the hydraulic system, thus avoiding influences from human factors. Hydraulic expansion is a technique in which high-pressure liquid is introduced directly into the tube, thereby expanding the tube using hydraulic force to achieve a tight fit between the tube and the tube sheet. This hydraulic pressure can be precisely set, measured, controlled, and replicated.

It depends on your requirements for expansion joining – determine whether mechanical expansion or hydraulic expansion is more suitable for you; you can learn more at www.keen-way.com

What people usually talk about is how to perform expansion joining and what tools to use. In fact, the principle of expansion bonding is to use a certain processing method to expand the heat exchange tubes, causing plastic deformation; meanwhile, the holes in the tube sheet expand elastically during this plastic deformation of the tubes. After the processing is complete, the holes in the tube sheet rebound, thereby achieving a tight connection with the heat exchange tubes.