How to protect custom ERW from biological corrosion?

Hey there! I'm a supplier of custom Electric Resistance Welded (ERW) pipes. Over the years, I've seen firsthand how biological corrosion can mess up these pipes big time. Biological corrosion, also known as microbiologically influenced corrosion (MIC), is a real pain in the neck for anyone dealing with custom ERW pipes. In this blog, I'll share some tips on how to protect custom ERW from biological corrosion.

Understanding Biological Corrosion

First things first, let's talk about what biological corrosion is. It's caused by the activities of microorganisms like bacteria, fungi, and algae. These little critters can form biofilms on the surface of the ERW pipes. A biofilm is like a slimy layer that protects the microorganisms and creates a unique environment where corrosion can happen more easily.

The microorganisms in the biofilm can produce acids, enzymes, and other corrosive substances. For example, sulfate - reducing bacteria (SRB) are a common culprit. They break down sulfate in the environment and produce hydrogen sulfide gas, which is highly corrosive to metal. Once the corrosion starts, it can spread quickly and cause leaks, structural damage, and other serious problems in the custom ERW pipes.

Factors Affecting Biological Corrosion

There are several factors that can influence the growth of microorganisms and the occurrence of biological corrosion in custom ERW pipes.

• Temperature: Microorganisms have an optimal temperature range for growth. For most bacteria, this range is between 20°C and 40°C. If the temperature of the fluid flowing through the ERW pipes is within this range, it can promote the growth of bacteria and increase the risk of biological corrosion.
• pH Level: The pH level of the fluid also matters. Some microorganisms prefer acidic conditions, while others thrive in alkaline environments. A neutral pH is generally less favorable for the growth of most corrosive bacteria.
• Oxygen Availability: Different microorganisms have different oxygen requirements. Aerobic bacteria need oxygen to grow, while anaerobic bacteria, like SRB, can grow in the absence of oxygen. The oxygen content in the fluid flowing through the pipes can determine which type of bacteria will dominate.

Preventive Measures

Now, let's get to the good stuff - how to protect custom ERW from biological corrosion.

Material Selection

Choosing the right material for custom ERW pipes is crucial. Some materials are more resistant to biological corrosion than others. For example, stainless steel is a great option. It has a passive oxide layer on its surface that can resist the attack of corrosive substances produced by microorganisms. You can check out our Cold Rolled Thin - wall Stainless Steel Tubing, which is a high - quality option for applications where biological corrosion is a concern.

Alloy steels can also be a good choice. For instance, 16Mn 25mn Precision Cold Rolled Seamless Steel Tube has better corrosion resistance compared to regular carbon steel due to the addition of alloying elements. Another option is 27SiMn Precision Low Alloy Thin Wall Carbon Steel Tube, which combines the strength of carbon steel with the corrosion - resistant properties of alloying elements.

Surface Treatment

Proper surface treatment can create a barrier between the ERW pipes and the microorganisms. One common method is coating. There are different types of coatings available, such as epoxy coatings, polyethylene coatings, and zinc coatings. Epoxy coatings are popular because they can provide excellent adhesion and corrosion protection. They form a hard, durable layer on the surface of the pipes that prevents microorganisms from coming into direct contact with the metal.

Another surface treatment option is passivation. This process involves treating the surface of the metal with a chemical solution to remove impurities and create a more stable oxide layer. Passivation can improve the corrosion resistance of the ERW pipes, especially for stainless steel pipes.

Water Treatment

If the custom ERW pipes are used in a water - based system, water treatment is essential. You can use chemicals to control the growth of microorganisms in the water. Chlorine is a commonly used disinfectant. It can kill bacteria and other microorganisms in the water. However, you need to be careful with the dosage of chlorine, as too much chlorine can also cause corrosion in some cases.

Other water treatment methods include using biocides. Biocides are chemicals that specifically target and kill microorganisms. There are different types of biocides available, such as oxidizing biocides and non - oxidizing biocides. Oxidizing biocides, like chlorine and bromine, work by reacting with the cell membranes of microorganisms and destroying them. Non - oxidizing biocides, on the other hand, work by interfering with the metabolic processes of the microorganisms.

Monitoring and Maintenance

Regular monitoring is key to detecting biological corrosion early. You can use techniques like corrosion coupons, which are small pieces of the same material as the ERW pipes. These coupons are placed in the system, and the amount of corrosion on the coupons can be measured over time. If the corrosion rate on the coupons is high, it indicates that there may be a problem with biological corrosion in the pipes.

Visual inspection is also important. You can look for signs of biofilm formation, such as a slimy layer on the inner surface of the pipes, or signs of corrosion, like rust or pitting. If you notice any problems, you can take corrective actions immediately, such as cleaning the pipes or adjusting the water treatment program.

Conclusion

Biological corrosion is a serious issue for custom ERW pipes, but it can be managed. By understanding the causes and factors affecting biological corrosion, and by taking preventive measures like proper material selection, surface treatment, water treatment, and regular monitoring, you can significantly reduce the risk of corrosion and extend the lifespan of your custom ERW pipes.

If you're interested in purchasing high - quality custom ERW pipes or need more information on protecting them from biological corrosion, feel free to reach out. We're here to help you find the best solutions for your specific needs.

References

• Fontana, M. G. (1986). Corrosion Engineering. McGraw - Hill.
• Uhlig, H. H., & Revie, R. W. (1985). Corrosion and Corrosion Control. Wiley - Interscience.