Help needed regarding a heat exchanger leak!
Thread Content
Currently, there are over 20 shell-and-tube heat exchangers (both with single and double tube sheets), which are used to handle flammable, explosive, toxic, and corrosive media such as hydrogen and chlorosilanes. However, during inspection upon arrival at the site, leaks were found between the heat exchange tubes and the tube sheets (in many units, both the inner and outer tube sheets were leaking). According to the construction drawings, hydrostatic testing, non-destructive testing, and ammonia leak testing had been carried out prior to departure from the factory. However, when the goods arrived at the site and a nitrogen leak test was conducted, leaks were found at both the welded and expansion-jointed areas! I’m very worried!!!! I’d appreciate it if experts could advise me (on the reasons and solutions), as I’m concerned about safety in the future! ! ! Because the cooling medium is water, contact with the material can cause blockages or even explosions! ! ! ! !
Reason: In the vast majority of cases, leaks in shell-and-tube heat exchangers are caused by problems with the welding between the heat exchange tubes and the tube sheet; uneven temperatures during the expansion process can easily lead to stress cracks. Solution: If repair is carried out, it will take more time, and the results of such repairs will not be very good. The best approach is to carry out the repairs on-site. If the traditional surfacing method is continued used, the stresses cannot be eliminated; fixing one leak will only lead to more leaks. By using polymer composite materials, the repair is both effective and quick – all that is needed is to clean the weld areas between the heat exchanger tubes and the tube plates, then apply the polymer composite material to those areas as if applying paint, followed by allowing it to dry. Generally, it takes only half an hour to an hour to repair a heat exchanger. Polymer composite materials, with their resistance to acid and alkali corrosion and strong adhesion, can be fully utilized for repairing leaks in heat exchangers. The most important thing: in the future, when purchasing equipment, compare options from different suppliers to buy products of high quality.
What was said upstairs makes a lot of sense; I’ve learned it! It’s better to use fully welded heat exchangers; this not only avoids the possibility of dead zones arising from connections, but also makes the welded joints stronger, thereby significantly reducing the risk of leaks.
"Hydraulic testing, non-destructive testing, and ammonia leak detection have been carried out prior to leaving the factory. But performing a gas-tightness test using nitrogen upon delivery to the site indicates a problem in manufacturing; chlorosilanes are most sensitive to leaks of liquid or gas
2# beifang0533 The administrator asked about polymer composite materials technology, so I’ll give a brief explanation. Polymer composite materials refer to multiphase materials formed by combining polymer materials with other substances that have different compositions, shapes, and properties. The greatest advantage of polymer composite materials is that they combine the best properties of various materials, such as high strength, light weight, heat resistance, corrosion resistance, thermal insulation, and electrical insulation. Depending on the intended application, polymer materials along with other materials possessing special properties are selected to create composite materials that meet the required specifications. Based on the information we currently have regarding materials such as Fushi Blue polymer composites and Akko polymer composites, polymer composites possess the following advantages: 1. Excellent adhesion: Polymers penetrate and create forces between molecules, enabling van der Waals forces and hydrogen bonds to form between them and the component being repaired. 2. Excellent mechanical properties: The requirements for various composite forces generated during the operation of mechanical equipment were analyzed, and balance among various data was achieved during the material synthesis process. It also possesses good machinability and ductility. 3. Resistance to chemical corrosion: It addresses the corrosion caused by organic acids, inorganic acids, and mixed acids at high temperatures. 4. Safety of the material: 100% solid, with no volatility in the material ； It is non-toxic and harmless, and can come into direct contact with the skin. It is precisely because polymer composite materials possess such excellent properties that they are attracting increasing attention from research institutions and enterprises, and are being used in various industries. The main causes of leaks in heat exchangers are corrosion and erosion by chemical substances, or defects in the material itself; therefore, the corrosion resistance and ease of use of polymer composite materials can be utilized to address these issues effectively. If you want to learn about methods for addressing leaks in heat exchangers, please check out my Haichuan Space!
4# jlchina is unsure whether the manufacturer actually carried out these tests; with so many leaks occurring, it should not have been possible for leaks to occur after nitrogen pressure testing following those tests.
Testing should have been carried out, but the stress at the weld points has not been eliminated; moreover, vibrations during transportation can all lead to reoccurrence of leaks. If the corrosion resistance is satisfactory, try fixing it with repair glue. Stress will still be present if the remelting welding operation is not done properly.
In fact, many manufacturers do not produce double-sheet plate assemblies very well, especially when it comes to the expansion joint part. As the original poster mentioned, inspections have been carried out; you can contact the manufacturer. If there are many leakage issues, they will have their own explanations. In the case of polysilicon, if leaks occur, the product is basically considered unusable. There are a few manufacturers in China that do a good job in this area: Jiangyin Shuangliang, Shanghai Sensong, and Nanjing Zhongsheng – all of them produce high-quality double-sheet plate assemblies
Replace it directly with a leak-proof one to avoid more serious accidents in the future