Heat exchanger tube plate anti-corrosion how to protect the effect better

The material of heat exchanger is generally based on carbon steel, stainless steel and copper, and the connection between plate and tube is generally in the form of welding, expansion and expansion welding combination.

The anti-corrosion protection of the tube plate and tube using expansion welding combined way, due to the shape of the weld exists in varying degrees of defects, such as depressions, porosity, slag, etc., the distribution of weld stress is also uneven, weld welding led to changes in its own material, when encountering corrosive media, the weld position is very easy to corrosion, rust caused by leakage in the weld position.

Secondly, the chlorine ions in the water and electrochemical corrosion problems are also prone to cause corrosion in the weld position resulting in leakage, affecting the service life of the heat exchanger and causing losses to the production enterprises. For a long time this problem has not been properly solved and has become an industry problem.

The development of heat exchanger tube plate corrosion technology

For corrosive media caused by the heat exchanger tube plate and weld position corrosion problems, the traditional way is to play pressure mark leakage point 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, by upgrading the material grade of the equipment itself, to improve the corrosion resistance of the body and extend the service life, but will add a lot of costs to the enterprise.


Polymer composite material protection process.

The use of polymer materials to implement surface organic coating anti-corrosion is currently one of the proven anti-corrosion measures.

Polymer composites are high-tech disciplines developed on the basis of polymer chemistry, organic chemistry, colloid chemistry and mechanics of materials, using polymer penetration to form forces between molecules, so that they form van der Waals forces and hydrogen bonding links with the repair parts, thus ensuring their bonding performance with the repair and protection parts.

Polymer composites can form a protective coating in cured form on the protected substrate and act as a shield, separating the base metal from corrosive media to avoid corrosion and rusting.

The coating has anti-penetration properties, stability to corrosive media, strong adhesion and compatible mechanical properties, which ensure the application effect of the protective coating and the operating cycle of the equipment.

Compared with the traditional welding repair, the 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 good application experience and technical products.

Overview of heat exchanger tube plate anti-corrosion solution

The article takes as an example the corrosion protection of a heat exchanger in a large coal chemical industry with a diameter of 3 m, a shell process pressure of up to 17 kg and a tube process temperature of up to 150°C. The heat exchanger has a high pressure of 17 kg and a maximum temperature of 150°C. The harsh working environment places higher demands on technology and products.

The surface of the tube plate is first sandblasted to remove surface rust and other impurities, and after the surface treatment meets the requirements, polymer composite materials are used to protect the surface of the tube plate as a whole against corrosion.


Heat exchanger tube plate anti-corrosion steps

Preparation: dismantle the heat exchanger head to ensure construction safety and leave an operable space.

2. Pressure testing for leaks: pressure test for leaks and cracks at rated pressure and mark the location for patching (until there are no cracks or leaks before proceeding to the next step).

3. drying treatment: dry the parts to be protected to ensure that the surface of the parts is dry and free of water.

4. surface treatment: sandblasting treatment to clean the surface adherence, reveal the original metal colour and meet Sa2.5 standard.

5. cleaning the surface: blowing the dust dry with compressed air (free of water and impurities).

6. blending the material: polymer composite until uniform and free of colour differences.

7. implementing the coating treatment in steps according to the thickness requirements of the coating and the technical requirements of the protection, with a minimum of two coats and a total thickness of ≥ 0.5 mm of anti-corrosion coating.

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, after meeting the requirements, it can be installed and used. Avoid impact and knocking on the repaired part during installation.
Source: Internet
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