How to prevent corrosion of seamless pipes?

Corrosion is the main problem affecting Seamless Pipes (SMLS) in various industries. Corrosion can accelerate the aging of pipes, causing serious damage and leading to expensive repair and replacement costs. Delaying the corrosion of pipes, namely seamless pipe anti-corrosion, is an important part of pipeline maintenance and one of the key points in promoting safe production in the pipeline transportation industry. In this article, we will discuss the causes of corrosion of seamless pipes and the various methods that can be used to prevent corrosion.

Causes of Seamless Pipe Corrosion:

Corrosion of seamless pipes is caused by a variety of factors, which can be attributed to the following aspects:

1. Chemical corrosion

a. Surface contamination: Substances such as oil, dust, acid, alkali and salt attached to the surface of seamless pipes may be converted into corrosive media under certain conditions, and react chemically with certain components in seamless pipes, resulting in chemical corrosion and rust.

b. Surface scratches: Scratches on the surface of seamless pipes will damage their passivation film, reduce their protective ability, and make seamless pipes more likely to react with chemical media and produce chemical corrosion.

c. Incomplete cleaning: During the production or maintenance of seamless pipes, if the cleaning is not thorough, residual acid, alkali and other liquids will remain on the surface, which may also cause chemical corrosion.

2. Electrochemical corrosion

a. Carbon steel contamination: When seamless pipes come into contact with carbon steel parts or corrosive media, they may form a primary battery due to scratches and other reasons, resulting in electrochemical corrosion.

b. Process effects such as cutting and welding: During the cutting and welding of seamless pipes, rust-prone substances (such as cutting slag and spatter) may be attached to the surface, or physical or chemical defects may be caused by improper processes, which will increase the risk of electrochemical corrosion.

c. Material defects: The chemical composition of seamless pipe materials is uneven, contains impurities such as S and P, or there are physical defects such as pores, sand holes, and cracks on the surface, which may form a primary battery in the corrosive medium and cause electrochemical corrosion.

d. Poor passivation: During the pickling and passivation process of seamless pipes, if the passivation film is uneven or thin due to improper treatment, it is also easy to cause electrochemical corrosion.

3. Environmental factors

a. Corrosive environment: The use of seamless pipes in corrosive environments, such as humid, acidic, alkaline or high-salt environments, will accelerate their corrosion process. For example, pipes used in the chemical industry are susceptible to corrosion due to exposure to acidic and alkaline substances.

b. Temperature changes: Changes in temperature may also affect the corrosion rate of seamless pipes, especially under extreme temperature conditions, the corrosion resistance of seamless pipes may be reduced.

c. Microbial activity: Microbial activity can cause corrosion of seamless pipes. Bacteria and fungi can thrive in the presence of moisture and oxygen, producing acidic substances that can corrode pipes.

4. Improper use and maintenance

a. Improper installation: During the installation process, if the seamless pipe is not installed and fixed according to the specifications, it may cause additional stress or vibration to the pipe, thereby accelerating corrosion.

b. Untimely maintenance: During the use of seamless pipes, if they are not maintained and inspected in time, they may cause safety problems such as leakage due to corrosion problems.

Methods to Prevent Corrosion of Seamless Pipes:

During the use of seamless pipes, they are easily affected by oxidation and corrosion, so some measures need to be taken for anti-corrosion treatment. Here are some common methods for seamless pipe anti-corrosion:

1. Prevent mechanical damage

During the production process, seamless pipes will inevitably have quality defects, such as mechanical damage such as scratches, dents and cracks, which will cause corrosion of seamless pipes. These damages will expose the pipes to moisture, oxygen and other corrosive substances, which will cause corrosion. Therefore, when purchasing seamless pipes, strict quality inspection and acceptance should be carried out.

2. Prevent moisture
When seamless pipes are stored, they should be avoided from contact with humid environments such as water vapor and rain. You can choose to build a rainproof shed around the seamless pipes or use a moisture-proof agent to keep the environment dry, or use moisture-proof packaging materials for packaging.

3. Surface treatment
Seamless pipes can be surface treated, such as spraying a layer of anti-rust paint on the surface of seamless steel pipes or using an anti-corrosion layer such as hot-dip galvanizing to form a protective film, which can prevent seamless pipes from contacting oxygen and moisture in the air and effectively prevent rust.

Pipe coating is one of the most effective ways to prevent corrosion of seamless pipes. Coatings protect pipes from environmental factors, oxygen and microbial activity. Different types of coatings can be used, including epoxy resin, polyurethane and zinc coatings.

Epoxy coatings are commonly used in the oil and gas industry because of their resistance to chemicals and high temperatures. Polyurethane coatings are used in the marine industry because of their resistance to water and salt. Zinc coatings are used to protect pipes from rust and can be applied through galvanizing.

4. Corrosion Inhibitors
Corrosion inhibitors are chemicals that can be used to prevent corrosion in seamless pipes. Corrosion inhibitors work by forming a protective layer on the surface of the pipe, thereby preventing rust.

Different types of corrosion inhibitors can be used, including organic inhibitors, inorganic inhibitors, and mixed inhibitors. Organic inhibitors are used in the oil and gas industry because of their resistance to high temperatures and chemicals. Inorganic inhibitors are used in the water treatment industry because of their resistance to water and salt.

5. Isolation of material contact
Avoid contact between seamless steel pipes and harmful chemicals, acid and alkali substances, etc., which may accelerate the rust of steel pipes.

6. Regular cleaning and maintenance
After the seamless steel pipe has been used for a period of time, it should be cleaned and maintained regularly to remove dirt and impurities on the surface in time, keep its surface smooth and reduce the chance of rust.

7. Control the environment
Try to transport and store seamless pipes in relatively stable environmental conditions to avoid damage to the pipes caused by excessively high or low temperatures and humidity. In addition, appropriate seamless pipe materials, such as carbon steel, stainless steel, alloy steel, etc., should be selected according to the use environment to extend the service life.

8. Microscopic repair
For seamless steel pipes that have already rusted, microscopic repair methods such as electrochemical protection and phosphating of the steel pipe surface can be used to repair the rusted parts that have already occurred and prevent further spread.

9. Cathodic protection
Cathode protection is a method of preventing corrosion of seamless pipes that uses electric current to protect pipes from corrosion. Electric current is used to form a protective layer on the surface of the pipe to prevent rust.

There are two types of cathodic protection: sacrificial anode and impressed current. Sacrificial anode cathodic protection involves attaching a more active metal to the pipe, which will corrode instead of the pipe. Impressed current cathodic protection involves passing an electric current through the pipe to form a protective layer.

Conclusion:
There are many reasons why seamless pipes are easily corroded, including chemical corrosion, electrochemical corrosion, environmental factors, and improper use and maintenance. In order to reduce the corrosion risk of seamless pipes, effective anti-corrosion measures need to be taken, such as selecting high-quality and reliable manufacturers when purchasing, selecting appropriate anti-corrosion coatings, strengthening surface treatment, optimizing storage and use environments, and regular inspections and maintenance.

In the production, transportation, storage and use of seamless pipes, continuous adoption of appropriate anti-rust measures can extend the service life of seamless pipes and reduce economic losses caused by rust.

Read more:  Seamless Steel Pipe Manufacturing Process or Analysis of Seamless Steel Pipe Costs