Causes of welded steel tube corrosion

With the continuous development of the economy and the rapid development of construction, transportation, energy and other industries, the demand for pipelines is increasing day by day, and the use of pipelines is becoming more and more extensive, ranging from transporting water, oil, and gas to transporting large amounts of solid materials. Among them, welded steel tube is a commonly used pipe material with the advantages of high strength, corrosion resistance, easy processing, etc., and is widely used in various industries. However, as the use time increases, corrosion of welded steel tube(such as ERW pipe) gradually becomes a problem worthy of concern.

Causes and types of welded steel tube corrosion

Welded steel tube corrosion can occur on the inner wall, outer wall or the surface of the entire structure and is usually caused by physical, chemical, electrochemical or microbiological processes. These processes lead to corrosion and damage to the pipe wall, which has a serious impact on the integrity of the pipeline and endangers the safety of equipment and personnel.

The causes of welded steel tube corrosion mainly include the following aspects:

1. Chemical action

There may be some chemical substances in the medium transported by welded steel tube, such as chloride ions, sulfates, nitrates, etc. The presence of these substances will cause a certain chemical reaction on the inner wall of the steel pipe, producing a substance with a different chemical composition from that of the steel pipe. This leads to corrosion of the pipeline.

2. Electrochemical effect

When a welded steel tube comes into contact with some metals or solids, liquids or gases with good electrical conductivity, electrochemical corrosion will form. In this case, the steel pipe acts as a cathode and is reduced by oxides or hydrogen ions. This reduction process releases electrons, causing corrosion of the steel pipe.

3. Microorganisms

Welded steel tube corrosion may also occur due to biological corrosion caused by microorganisms. When water or soil containing microorganisms is used for transportation, microorganisms will grow on the inner wall of the pipeline. These microorganisms can produce acid and alkali substances and accelerate the corrosion of the pipeline.

For different causes of welded steel tube corrosion, the main categories are:

1. Chemical corrosion: mainly includes acid corrosion, alkaline corrosion, oxidation corrosion, etc.

2. Electrochemical corrosion: mainly includes battery corrosion, discharge corrosion, etc.

3. Radiation corrosion: corrosion mainly caused by the action of radiation energy.

4. Wear and corrosion: Mainly caused by friction or wear caused by long-term use of pipelines, leading to pipeline damage.

Methods of protecting welded steel tube

1. Spray protective coating

Spraying protective paint is the most basic method to protect welded steel tubes. The spraying process will form a chemical isolation layer that can slow down the corrosion of the pipeline. Therefore, it is very important to choose protective coatings that meet the requirements, master spraying techniques, and conduct regular inspections and maintenance of pipelines.

2. Hot dip galvanizing

For welded steel tubes made of some metals, anti-corrosion can be achieved by hot-dip galvanizing(Hot dip galvanized pipe). That is, the heated steel tube is immersed in molten zinc, so that the zinc can chemically react with the surface of the steel tube to become a stable compound, forming a strong anti-corrosion layer. This method can be widely used in various pipelines, but attention needs to be paid to the selection of materials and specific operation methods.

3. Catholic protection

Cathodic protection is a commonly used corrosion protection method for welded steel tubes. Its basic principle is to add an external power supply to the surface of the steel tube to maintain it in the cathodic state at a certain potential, thereby achieving the anti-corrosion effect. The advantage of this method is that it can be applied to various application environments and can protect the entire pipeline, but it requires certain technical requirements for the selection of electrodes and power sources.

Causes of welded steel tube corrosion

With the continuous development of the economy and the rapid development of construction, transportation, energy and other industries, the demand for pipelines is increasing day by day, and the use of pipelines is becoming more and more extensive, ranging from transporting water, oil, and gas to transporting large amounts of solid materials. Among them, welded steel tube is a commonly used pipe material with the advantages of high strength, corrosion resistance, easy processing, etc., and is widely used in various industries. However, as the use time increases, corrosion of welded steel tube(such as ERW pipe) gradually becomes a problem worthy of concern.

Causes and types of welded steel tube corrosion

Welded steel tube corrosion can occur on the inner wall, outer wall or the surface of the entire structure and is usually caused by physical, chemical, electrochemical or microbiological processes. These processes lead to corrosion and damage to the pipe wall, which has a serious impact on the integrity of the pipeline and endangers the safety of equipment and personnel.

The causes of welded steel tube corrosion mainly include the following aspects:

1. Chemical action

There may be some chemical substances in the medium transported by welded steel tube, such as chloride ions, sulfates, nitrates, etc. The presence of these substances will cause a certain chemical reaction on the inner wall of the steel pipe, producing a substance with a different chemical composition from that of the steel pipe. This leads to corrosion of the pipeline.

2. Electrochemical effect

When a welded steel tube comes into contact with some metals or solids, liquids or gases with good electrical conductivity, electrochemical corrosion will form. In this case, the steel pipe acts as a cathode and is reduced by oxides or hydrogen ions. This reduction process releases electrons, causing corrosion of the steel pipe.

3. Microorganisms

Welded steel tube corrosion may also occur due to biological corrosion caused by microorganisms. When water or soil containing microorganisms is used for transportation, microorganisms will grow on the inner wall of the pipeline. These microorganisms can produce acid and alkali substances and accelerate the corrosion of the pipeline.

For different causes of welded steel tube corrosion, the main categories are:

1. Chemical corrosion: mainly includes acid corrosion, alkaline corrosion, oxidation corrosion, etc.

2. Electrochemical corrosion: mainly includes battery corrosion, discharge corrosion, etc.

3. Radiation corrosion: corrosion mainly caused by the action of radiation energy.

4. Wear and corrosion: Mainly caused by friction or wear caused by long-term use of pipelines, leading to pipeline damage.

Methods of protecting welded steel tube

1. Spray protective coating

Spraying protective paint is the most basic method to protect welded steel tubes. The spraying process will form a chemical isolation layer that can slow down the corrosion of the pipeline. Therefore, it is very important to choose protective coatings that meet the requirements, master spraying techniques, and conduct regular inspections and maintenance of pipelines.

2. Hot dip galvanizing

For welded steel tubes made of some metals, anti-corrosion can be achieved by hot-dip galvanizing(Hot dip galvanized pipe). That is, the heated steel tube is immersed in molten zinc, so that the zinc can chemically react with the surface of the steel tube to become a stable compound, forming a strong anti-corrosion layer. This method can be widely used in various pipelines, but attention needs to be paid to the selection of materials and specific operation methods.

3. Catholic protection

Cathodic protection is a commonly used corrosion protection method for welded steel tubes. Its basic principle is to add an external power supply to the surface of the steel tube to maintain it in the cathodic state at a certain potential, thereby achieving the anti-corrosion effect. The advantage of this method is that it can be applied to various application environments and can protect the entire pipeline, but it requires certain technical requirements for the selection of electrodes and power sources.

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