Anti-corrosion methods and anti-corrosion material selection for ERW steel pipes:
Anti-corrosion methods for ERW steel pipes:
ERW steel pipe anti-corrosion technology refers to the use of various methods on the surface or inside of welded steel pipes to slow down or prevent the corrosion process and extend the service life of the pipeline. These technologies include surface treatment, coating protection, cathodic protection, etc.
a. Surface treatment
Surface treatment is the basis of welded steel pipe anti-corrosion technology, including cleaning, rust removal, polishing and other steps. Through surface treatment, dirt, rust and other impurities on the surface of the pipeline can be removed, the smoothness and cleanliness of the pipeline surface can be improved, and a good base can be provided for subsequent coating protection.
b. Coating protection
Coating protection is to cover the surface of the pipeline with an anti-corrosion coating to isolate the pipeline from the external environment, thereby slowing down the corrosion rate. Commonly used coating materials include paint, resin, galvanizing, etc., which can effectively resist chemical corrosion, electrochemical corrosion and microbial corrosion.
c. Cathodic protection
Cathodic protection is a method of preventing corrosion by changing the potential on the surface of the pipeline so that the pipeline becomes the cathode in the entire corrosion battery. Cathodic protection can be divided into impressed current method and sacrificial anode method. The impressed current method uses an external power source to provide a protective current to the pipeline, making it a cathode; the sacrificial anode method connects a more active metal to the pipeline, making it an anode to protect the pipeline.
Commonly used anti-corrosion methods for ERW steel pipes include the following:
1. Spray painting method
The spray painting method is a commonly used anti-corrosion method for ERW steel pipes. Using a spray paint machine to spray special anti-corrosion paint on the surface of the steel pipe can protect the surface of the steel pipe from corrosion. The spray painting method has the advantages of convenient construction, economical and practical, and remarkable effects. However, its disadvantage is that it is easily affected by climate and external environmental factors, and the anti-corrosion effect is not very lasting.
2. Hot dip galvanizing method
Hot-dip galvanizing is also a commonly used anti-corrosion method for ERW steel pipes. It uses zinc to form a galvanized layer on the surface of the steel pipe to prevent the steel pipe from rusting. Hot-dip galvanizing has the advantages of good anti-corrosion effect and long service life, but the disadvantage is higher cost.
3. Zinc spraying method
The zinc spray method is an emerging anti-corrosion method for steel pipes in recent years. It uses a sandblasting machine to spray zinc spray materials on the surface of the steel pipe to form a zinc-iron alloy layer and a pure zinc layer, which can effectively prevent the steel pipe from rusting. The zinc spray method has the advantages of good anti-corrosion effect and low cost, but it requires subsequent treatment to extend the service life of the steel pipe.
4. Welding seam treatment
The weld is an important source of corrosion in steel pipes. Therefore, when welding steel pipes, special anti-corrosion treatment is required for the weld. Generally, brushing, spraying, coating and other methods are used to carry out anti-corrosion treatment on welds to protect the service life of steel pipes.
5. Heat treatment
Heat treatment is another method for anti-corrosion of
welded pipes. High temperature treatment can improve the performance of the pipe wall and make the welded pipes more durable. Commonly used heat treatment methods include annealing, normalizing, quenching, etc. Different heat treatment methods have different effects on improving the performance of pipes. It needs to be selected according to the material and usage requirements of the pipe.
6. Anti-corrosion testing
After completing the above anti-corrosion measures, anti-corrosion testing is also required to check whether the anti-corrosion effect of the welded pipe meets the requirements. Anti-corrosion testing generally includes coating thickness measurement, adhesion testing, acid and alkali resistance and chemical resistance testing, etc. to ensure the durability and safety of welded pipes.
Selection and use of ERW steel pipe anti-corrosion materials:
Anti-corrosion of welded pipes is to prevent the pipes from being corroded during use, thereby reducing the service life of the pipes. Commonly used anti-corrosion materials for welded pipes mainly include the following:
1. Polyethylene (PE): It has good corrosion resistance and is widely used in natural gas, city gas, water supply, industrial water pipelines and other fields.
2. Polypropylene (PP): Resistant to chemical corrosion, suitable for various chemical medium pipelines and chemical industry pipelines. However, its corrosion resistance is weak and it is not suitable for medium pipelines such as strong acid and strong alkali.
3. Epoxy fiberglass anti-corrosion layer (FBE): It has good corrosion resistance and is widely used in petroleum, natural gas, chemical industry, urban water supply and drainage, marine engineering, heating and other fields.
How to choose suitable anti-corrosion materials for ERW steel pipes?
1. Selection of pipeline usage environment: Different materials have different adaptability to different environments. For example, in a salt water environment, materials with better corrosion resistance to salt water should be selected.
2. Selection of medium characteristics: Medium characteristics are also an important factor in selecting anti-corrosion materials for welded pipes. For example, media such as strong acid and strong alkali are highly corrosive to some materials, so materials with strong corrosion resistance need to be selected.
3. Pipe shape selection: Pipes of different shapes require different anti-corrosion material treatment methods. For example, pipe elbows, tees, etc. need to be coated with water-blocking glue.
Practical tips:
1. Before using ERW welded pipes, the surface of the steel pipe must be cleaned to remove surface grease and rust to facilitate the construction of anti-corrosion treatment.
2. When carrying out anti-corrosion treatment on steel pipes, attention should be paid to the dryness and appropriate temperature of the construction environment to ensure the anti-corrosion effect.
3. When storing and transporting ERW welded pipes, care should be taken to prevent moisture and rain erosion.
Conclusion:
When ERW steel pipes require anti-corrosion treatment during use, choosing appropriate anti-corrosion materials is the key to ensuring the service life of ERW welded steel pipes. At the same time, attention should be paid to techniques during construction to ensure the durability and reliability of the anti-corrosion treatment effect.
Tips: ASTM A53 is the grade of ERW high-frequency welded pipe, which is divided into Grade A and Grade B. ASTM A53 Grade B ERW is more popular than other grades. These pipes can be bare without any coating, or they can be hot dipped or galvanized and manufactured through welding or seamless manufacturing processes. In Oil and Gas, A53 grade pipes are used in the structural and non-critical applications.
Read more: ERW Pipe VS Seamless Pipe
