Heat exchanger tube plate anti-corrosion how to protect the effect of better
Heat exchanger material is generally based on carbon steel, stainless steel and copper, plate and tube connection is generally welding, expansion and expansion welding combination of the way.
The anti-corrosion protection of the plate and tube using the expansion welding combination, due to the shape of the weld seam there are different degrees of defects, such as depressions, porosity, slag, etc., the distribution of weld stress is also uneven, the weld seam welding led to changes in its own material, in the encounter with corrosive media, the weld position is very easy to corrosion, rust caused by leakage at the weld position.
Secondly, the chloride ions in the water and electrochemical corrosion problems are also prone to cause corrosion of the weld position resulting in leakage, affecting the service life of the heat exchanger, causing losses to the production enterprises.
For a long time this problem has not been properly solved, becoming an industry problem.
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The development of heat exchanger tube plate anti-corrosion process
For corrosive media caused by heat exchanger tube plate and weld seam position corrosion problems, the traditional way is to hit the mark leak after the way to patch welding.
However, after welding, the release of welding stress and welding position material changes, are prone to cause secondary corrosion leakage of the tube plate. In addition to improve the corrosion resistance of the body by upgrading the material grade of the equipment itself to extend the service life, but it will add a lot of cost to the enterprise.
02
Polymer composite material protection process
The use of polymer materials to implement surface organic coating anti-corrosion is currently one of the effective anti-corrosion measures. Polymer composite material is a high-tech discipline developed on the basis of polymer chemistry, organic chemistry, colloid chemistry and material mechanics, etc. It uses polymer penetration to form the force between molecules, so that it forms van der Waals force and hydrogen bonding link with the repaired parts, thus ensuring its bonding performance with the repaired and protected parts.
Polymer composites can form a cured form of protective coating on the protected substrate and play a shielding role, so that the base metal and corrosive media are separated from each other to avoid corrosion and rusting; the coating has anti-penetration properties, stability to corrosive media, strong adhesion, compatible mechanical properties, etc., which ensures the application effect of the protective coating and the operating cycle of the equipment. Compared with the traditional welding repair, anti-corrosion coating protection technology has the characteristics of easy construction, low cost, high safety and good repair effect. In this regard, Fusiland polymer composite technology has very good application experience and technical products.
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Overview of heat exchanger tube plate anti-corrosion solution
The article takes a large coal chemical industry’s heat exchanger corrosion protection as an example, with a diameter of 3 meters, shell process pressure up to 17 kg, and tube process temperature up to 150 ℃. The harsh working environment has put forward higher requirements on our technology and products. After the surface treatment meets the requirements, polymer composite material is used to protect the surface of the tube plate as a whole against corrosion.
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Steps of heat exchanger tube plate anti-corrosion
1. preparation: dismantle the heat exchanger head to ensure construction safety and leave an operable space.
2. pressure testing for leaks: pressure testing for leaks and cracks according to the rated pressure and marking the location for patch welding (until the next step is guaranteed to be free of cracks and leaks).
3. Dry treatment: dry treatment of the parts to be protected to ensure that the surface of the parts is dry and free of water stains.
4. surface treatment: sandblasting treatment to clean up the surface adhesion, reveal the original metal color and reach Sa2.5 standard.
5. cleaning the surface: blowing the dust dry with compressed air (no water and no impurities).
6. blending materials: polymer composite material until uniform and without color difference.
7. according to the thickness requirements of the coating and protection technology requirements, step-by-step implementation of coating treatment, a minimum of two coats, the total thickness of anti-corrosion coating ≥ 0.5 mm.
8. curing: natural curing or heating up to cure.
9. inspection: after the material has reached the curing requirements, use EDM to detect the covering compactness of the anti-corrosion material, and use a thickness gauge to measure the thickness of the coating, which can be installed and used after meeting the requirements. Avoid impact and knocking on the repaired parts during installation.
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