Heat exchanger tube is a device used to transfer heat, usually composed of one or more tubes. During the heat transfer process, the liquid or gas in the tube will be heated or cooled to achieve heat transfer. There are mainly seamless steel pipe and welded steel pipe. Heat exchanger tubes are usually made of stainless steel, copper, nickel alloys and other materials. These materials have high corrosion resistance and can be used in harsh environments.

Corrosion properties of different materials
‌Corrosion allowance‌ refers to the thickness that a material may lose due to corrosion under specific environmental and use conditions. It is used to predict and calculate the loss of materials in a corrosive environment to ensure the safety and durability of the material during use. ‌
The corrosion properties of different materials vary. In a chemical environment, some materials are susceptible to corrosion, which can lead to thinning of the tube wall, loss of strength, and even safety hazards such as leakage. In order to avoid this situation, some equipment needs to consider the corrosion allowance, that is, to increase a certain wall thickness during design to ensure that failure will not occur during use.

Reasons for not considering corrosion allowance
‌1. Material selection: Heat exchanger tubes usually use materials with good corrosion resistance, such as stainless steel. The corrosion resistance of these materials is much better than that of carbon steel, so there is no need to provide additional corrosion allowance by increasing the wall thickness.
2. Design life: The heat exchanger tube bundle is a consumable part, and its design life is usually not required to be the same as the design life of the equipment or pipeline. Heat exchanger tubes can be replaced, while components such as tube sheets cannot be replaced, so the thickness design of heat exchanger tubes does not need to consider long-term corrosion allowance like pipelines or equipment.
3. Use environment: The working environment of heat exchanger tubes usually includes conditions such as high temperature and high-speed fluid, which may cause corrosion. However, the occurrence of corrosion can be effectively reduced by reasonable material selection and regular maintenance.
‌4. Economic efficiency: Increasing the corrosion allowance will increase material cost and processing difficulty. Since the heat exchanger tube bundle is a consumable part, the economic benefits brought by increasing the thickness are not obvious.

‌Main causes and prevention methods of heat exchanger tube corrosion‌
‌1. Causes‌: Corrosion and leakage of heat exchanger tubes are generally caused by local stress concentration on the tube wall. Friction, vibration, scale and other reasons will cause the surface of the tube wall to be uneven, which is easy to cause stress concentration and then cause corrosion‌.
‌2. Classification‌: Corrosion and leakage of heat exchanger tubes can be divided into shallow corrosion and deep corrosion. Shallow corrosion is manifested as a certain degree of corrosion on the surface of the tube wall, but no perforation; deep corrosion is manifested as severe corrosion on the surface of the tube wall, and perforation has occurred‌
‌3. Prevention methods‌: Reasonably select materials‌, and select materials with good corrosion resistance according to the properties of the medium‌. Regularly maintain the heat exchanger to promptly detect and eliminate scale, sediment, etc.‌. Strengthen monitoring, install monitoring equipment such as pressure gauges and flow meters, and promptly detect abnormal conditions and take measures‌. Perform reasonable water treatment to prevent the generation of scale, etc.‌. Install isolation equipment‌, and use isolation equipment for protection in places prone to corrosion‌

Summary
When using heat exchanger tubes, in order not to affect the heat exchange efficiency, we need to select suitable materials and design according to actual conditions to ensure the safety and reliability of the equipment.