Analysis of Common Leakage Issues in Titanium Tube Heat Exchangers
Traditional Design and Manufacturing Challenges
Due to the high cost of titanium, traditional stuffing box Titanium Tube Heat Exchangers typically use titanium tubes for heat exchange, while the tube sheets are made of titanium-steel composite plates to reduce costs. However, since titanium and steel have poor weldability, the manufacturing process is challenging. To simplify production, tube boxes are usually not made of titanium-steel composite plates but instead use carbon steel or low-alloy steel with an internal rubber lining, which reduces both manufacturing difficulty and costs. Additionally, to further save material costs, components that do not come into direct contact with seawater are not made of titanium. For example, the skirt portion of the floating tube sheet is typically made of carbon steel to avoid the welding challenges associated with titanium and carbon steel. While this traditional design lowers costs, it also introduces significant leakage risks.
1. Leakage at the Floating Tube Sheet Seal
The most common type of leakage occurs at the seal of the floating tube sheet. According to user feedback, severe corrosion has been observed in this area, primarily due to the exposure of the carbon steel section of the floating tube sheet during the compression of the packing. There is a gap between the floating tube sheet and the inserted tube box, allowing seawater to come into direct contact with the carbon steel, leading to rapid corrosion and subsequent leakage. Studies indicate that when seawater directly contacts carbon steel, the exposed part of the floating tube sheet can corrode in a very short time. In severe cases, only a thin layer of titanium remains. Once such leakage occurs, repairs are extremely difficult. Even if early-stage corrosion is detected and temporarily repaired by welding, limitations in welding conditions and metal characteristics often result in rapid re-corrosion, posing a continuous risk of leakage. If the heat exchanger leaks due to carbon steel corrosion, complete equipment replacement is usually required to eliminate safety hazards.
2. Leakage Due to Titanium Tube Fracture
Another common cause of leakage is titanium tube fracture, which is often caused by abrasion or impact. Since titanium is expensive, thinner tube walls (typically around 0.5 mm) are used to reduce costs. During operation, seawater containing sand, shells, and other debris flows through the heat exchange tubes at high speed, causing scratches and wear. As the tube walls become thinner, both heat exchange efficiency and durability decline significantly, leading to premature tube fractures and leaks. Additionally, due to the complex structure of the heat exchanger and the difficulty of cleaning, repairing leaks in such cases is challenging. Typically, sealing the damaged tube openings is the only viable solution, but this severely impacts the overall heat exchange performance.
3. Leakage at Titanium Tube Joints
Leakage can also occur at the connection points between titanium tubes and tube sheets. This issue is mainly attributed to welding defects or damage caused by vibrations of the heat exchange tubes. Titanium welding is prone to deformation, and cold processing can easily lead to cracks. If welding quality is subpar or excessive vibration occurs, the joints can be damaged. Repairing such leaks is highly complex, often requiring component replacement or even a complete overhaul of the equipment.
Challenges in Repairing Titanium Components
In actual use, titanium welding deformation is significant, and shape correction is difficult. Particularly during cold processing, cracks can easily form. Furthermore, titanium exhibits strong elastic spring back after bending, making it challenging to achieve precise shaping. As deformation speed increases, titanium's tendency for work hardening also intensifies, significantly impacting the quality and limits of processing. These properties make titanium equipment difficult to repair, and in some cases, repairs can even lead to worse performance. Given these challenges, structural damage often cannot be effectively repaired, making component replacement a more practical solution.
Conclusion
Although the traditional stuffing box titanium tube heat exchanger design reduces initial manufacturing costs, it suffers from severe long-term reliability issues due to floating tube sheet corrosion, titanium tube wear and fractures, and joint failures. Given the challenges of titanium welding and repairs, optimizing design, improving material selection, and enhancing structural integrity are essential to reducing leakage risks and extending equipment lifespan.
