How To Repair Pipe Flange Corrosion?

Pipe flange corrosion refers to the corrosion phenomenon that occurs at the flange connection part in the pipeline system. Flanges are important components for connecting pipelines or equipment. They are usually made of metal and are used to connect the two ends of pipelines or between equipment. Why do pipe flanges corrode? How to prevent it? If it still corrodes, is there any way to repair it?

The main causes of pipe flange corrosion include the following aspects:

1. Environmental factors

The poor conditions of the flange installation environment are one of the main causes of corrosion. If the installation environment has corrosive environments such as sewage, high temperature, acid and alkali, the flange surface will begin to corrode and form rust. In addition, a humid and high humidity environment will also accelerate the oxidation process of the metal and form rust.

2. Material factors

Improper material selection of flanges can also cause corrosion. If the flange material is incompatible with the medium, or if the material itself has defects (such as cracks, pores, etc.), it will accelerate the corrosion process. For example, the chlorine gas delivered by the chlorine compressor is highly corrosive. If the flange material is not corrosion-resistant, corrosion will occur.

3. Installation and use factors

Improper installation and use of flanges can also cause corrosion. If the flange is not sealed tightly or tightened unevenly, it will cause medium leakage, thereby aggravating corrosion. During operation, improper operation (such as frequent start and stop, overpressure operation, etc.) will also cause impact and wear on the flange, thereby causing corrosion.

4. Electrochemical corrosion

If there are dust containing other metal elements or foreign metal particles attached to the surface of the stainless steel flange, micro batteries will be formed in humid air, triggering electrochemical reactions, destroying the protective film, and causing rust. In addition, organic juices, acids, alkalis, and salts will also form organic acids in the presence of water and oxygen, corroding the metal surface.

Preventive measures for pipe flange corrosion:

1. Choose suitable materials

Choose suitable materials according to different installation environments to prevent rust. At the same time, check whether there are scratches and damage on the flange surface before installation to avoid rust caused by incompatible contact materials.

2. Strengthen maintenance

Maintain the flange regularly, remove surrounding sewage and sediments, and prevent the impact of the environment on the flange and the accumulation of dirt to accelerate rust.

‌3. Keep dry‌

After the flange is installed, it should be kept dry to prevent moisture from entering the interior and causing rust. If the flange is installed near a water source, a waterproof cover and other facilities should be installed to prevent moisture from entering the interior.

‌4. Anti-corrosion coating‌

Use anti-corrosion coating or protective caps on the flange connection bolts to prevent corrosion. For parts that are difficult to maintain, severely corroded bolts should be checked and replaced regularly.

‌The repair methods for pipe flange corrosion mainly include the following‌:

‌1. Scrubbing method‌

If the flange is slightly rusted, the rust can be removed by scrubbing. The specific method is to apply a small amount of toothpaste, detergent or white wine to the rusted part, scrub it with a soft brush, and finally wipe it clean with a damp cloth.

2. ‌Chemical dissolution method‌

Use chemicals to remove rust. First, grind the rusted part with sandpaper, and then use rust remover to clean it. Wear protective gloves, masks, goggles and other equipment during operation‌.

3. Electrolysis method

This method requires professional equipment. The rusty metal is used as the anode to produce an oxidation-reduction reaction between the anode and the cathode, so that the rust is dissolved and falls off, achieving the rust removal effect.

‌4. Anti-rust oil brushing method

If the flange is often in a humid environment and is prone to rust, you can apply a layer of anti-rust oil every once in a while. The method of use is to wipe the impurities on the surface of the flange with a cloth first, and then apply anti-rust oil with a brush, which can effectively extend the service life of the flange.

‌5. Anti-rust paint coloring method

Apply a layer of anti-rust paint on the surface of the flange and then color it, which is both beautiful and practical.

6. Replacement method

If the flange is severely rusted and cannot be repaired by the above methods, the best solution is to replace it. No matter how good the repair method is, it cannot repair an overly rusted flange, and replacement is the only solution.

‌7. Maintenance paint solution

Use epoxy or polyurethane coatings directly bonded to the substrate, which is suitable for anti-corrosion protection of flanges. Although thickening the coating can solve the edge protection problem, it will seal the fasteners, making subsequent maintenance difficult.

‌8. Mechanical solution‌

Use protective covers and clamps to seal flanges and flange gaps, usually made of stainless steel or plastic with rubber sealing strips. This method has poor flexibility and requires covers or clamps that fully match flanges of various sizes.

9. Tape or semi-solid anti-corrosion tape solution

Use petrolatum tape, wax or elastic polymer wrapping tape wrapped around the surface of the substrate to provide reliable anti-corrosion protection.

10. Hot melt plastic solution‌

Use waxy fusible polymers heated at high temperatures to spray on the surface of the substrate. The advantage is that it can be remelted and reused, saving costs.

‌11. Polymer sealing bag solution‌

Use a sealing bag with a low permeability polymer to completely wrap the flange to provide comprehensive protection.

‌12. New peelable sealing film system‌

Designed specifically for protecting flanges, fasteners and related pipes, with safe and simple construction.

Summary

There are many reasons for pipe flange corrosion, including environmental factors, material factors, installation and other external factors. The specific repair method needs to be carried out according to the specific cause of corrosion. At the same time, preventive measures should be taken before use. After purchase, you can learn from the flange supplier or consult professionals to avoid losses caused by pipe flange corrosion.