What are the characteristics and classifications of G-type finned tubes?

G-type finned tube It is one of the most widely used threaded finned tubes today, effectively enhancing the heat transfer performance of heating elements and eliminating the drawbacks associated with bare tubes and wound‑fin tubes. Its total heat transfer surface area is several to dozens of times greater than that of a bare tube, enabling improved heat transfer while reducing flow resistance. Under the same heat exchange conditions, it can significantly reduce equipment footprint and material consumption, thereby improving the economic efficiency and operational reliability of heat exchangers.

High-frequency welding of threaded finned tubes involves heating steel strips and pipes in a plastic or molten state, leveraging the skin effect and proximity effect of high-frequency currents to achieve bonding under controlled pressure, thereby ensuring a robust weld. This method significantly outperforms insert‑welding (or full hot‑dip galvanizing) in terms of product quality—achieving a pin‑welding rate of 95%—as well as productivity and automation. The resulting material exhibits a thermal conductivity of 1.10 to 1.20 W/kg·°C and has found widespread application in power engineering, the metallurgical industry, cement production, construction, petrochemicals, and other sectors. With an excellent cost‑performance ratio and superior heat‑transfer characteristics, this technology is particularly well suited for heat‑transfer applications.

Wear resistance is also a distinct advantage of G‑type finned tubes. During the installation of certain components, their wear‑resistant properties enhance the durability of the equipment; moreover, some critical devices exhibit minimal volatilization during operation. As a result, finned tubes elevate the overall performance and reliability of the system, while also offering significant practical benefits for environmental protection.

What is the difference between finned tubes and welded tubes? Finned tubes and welded tubes are not the same. G-type finned tube To enhance heat transfer efficiency, fins are typically added to the exterior of heat exchange tubes to increase their total surface area (or internal surface area), thereby improving heat transfer performance. Such heat exchangers are referred to as finned tubes. Based on shape and structure, finned tubes can be classified into square-fin tubes, spiral-fin tubes, vertical-fin tubes, helical‑serrated fin tubes, and internally finned tubes. According to material, finned tubes may be categorized as single‑metal finned tubes or bimetallic composite finned tubes. Furthermore, finned tubes can be manufactured using various processes, including roll‑formed finned tubes, welded‑formed finned tubes, roll‑pressed finned tubes, and integral‑molded finned tubes. Welded steel pipes, also known as welded pipelines, are fabricated by rolling steel or steel strips and then welding them together.

What are the characteristics of G-type finned tubes?

1. The heat-transfer performance of G‑type finned tubes is closely linked to the contact thermal resistance between the fins and the tube; at the heart of this resistance lies the contact pressure between them. Clearly, welded‑chip and sleeve‑type finned tubes exhibit superior heat-transfer characteristics, followed by bimetallic rolled‑edge designs, while insertion‑ and winding‑type configurations perform less well. For KLM‑type finned tubes, re‑rolling increases the contact area by approximately 50%, with minimal sensitivity to outer‑diameter tolerances; after multiple cold‑cycle tests, they maintain excellent contact, resulting in low contact thermal resistance and high heat-transfer efficiency. Grooved finned tubes can enhance airflow turbulence, boosting the overall heat-transfer coefficient by about 20%.

2. At room temperature, as the wall temperature of G‑type finned tubes rises, the contact pressure between the pins and the tube changes, leading to corresponding variations in the contact thermal resistance. The magnitude of these fluctuations depends on the finned‑tube type and the initial contact pressure. Meanwhile, the clamping force around the chip decreases rapidly with increasing ambient temperature, causing the contact thermal resistance to rise sharply. Bimetallic rolling, by contrast, can remain relatively stable over a broader temperature range.

3. Atmospheric corrosion-resistant G-type finned tube The bottom tubes are protected by the wing to prevent atmospheric corrosion. Different types of finned tubes exhibit varying resistance to atmospheric corrosion, depending on their protective coating. Among these, bimetallic rolling offers superior protection, while all finned tubes with a hot‑dip galvanized surface also demonstrate good resistance to atmospheric corrosion. In chemical plants where corrosive gases are present or in coastal areas, special attention should be paid to selecting appropriate raw materials and tube designs; aluminum‑fin tubes are particularly susceptible to corrosion.

4. In many applications involving internally finned tubes, the allowable pressure depends on the material and wall thickness of the base tube, but it also varies with the type of finned tube. Rolled‑on base tubes (made of aluminum or copper) have very limited pressure resistance and are therefore unsuitable for use in air coolers. Base tubes with embedded fins feature rolled‑in grooves; during operation, their pressure rating decreases as the operating temperature rises.

5. Clean the fouling on the gas side of the G‑type finned tubes, typically using compressed air, steam, or high-pressure water. This method requires that the fins possess adequate structural rigidity.

6. From the perspective of raw material consumption for G‑type finned tubes, the periphery is low, while the bimetallic roll and sleeve are high. Aluminum used in bimetallic rolling consumes approximately one‑third to one‑half more than that required for chip‑wrapped fins. In terms of production, manufacturing, and processing costs, the periphery is lower, bimetallic rolling is higher, and the sleeve is also costly. Consequently, all finned tubes requiring surface hot‑dip galvanizing exhibit relatively high manufacturing costs, whether measured by raw material consumption or by the overall production and fabrication process.