What are the Steel Pipe Coating Types?

Date:2025-01-22Tags:Steel Pipe Coating , Plastic-coated steel pipe, coated steel pipe, 2LPE


What are the anti-corrosion methods for anti-corrosion steel pipes?

The anti-corrosion method of anti-corrosion steel pipes is generally to use coatings for anti-corrosion. Let's learn about the knowledge of coating anti-corrosion below. Anti-corrosion coatings are mainly used to protect solid metal surfaces, and occasionally non-metals.

Coating anti-corrosion refers to evenly applying a layer of coating on the surface of rusted metal pipes to isolate them from various corrosive media. It is one of the most basic ways to prevent corrosion of steel pipes. Composite materials or composite structures are increasingly used for anti-corrosion coatings on steel pipes. These materials and structures should have excellent dielectric properties, physical properties, stable chemical properties and a wide range of temperature adaptability.

1. Outer wall anti-corrosion coating: Types and use conditions of coating materials for the outer wall of the pipeline.

2. Inner wall anti-corrosion coating: A film applied to the inner wall of the pipe to prevent corrosion inside the pipe, reduce friction resistance, and increase the flow rate. Commonly used coatings are amine-cured epoxy resins and polyamide epoxy resins. In order to ensure that the coating is firmly bonded to the pipe wall, the inner wall of the pipe must be surface treated. Since the 1970s, the trend has been to use the same material for the inner and outer wall coatings of the pipe so that the inner and outer wall coatings can be carried out simultaneously.

3. Anti-corrosion and thermal insulation coating: On medium and small diameter hot crude oil or fuel oil pipelines, in order to reduce the heat dissipation from the pipeline to the soil, a thermal insulation and anti-corrosion composite layer is added to the outside of the pipeline. The commonly used thermal insulation material is hard polyurethane foam plastic, which is suitable for temperatures of -185 to 95°C. This material is soft in texture. In order to improve its strength, a layer of high-density polyethylene is applied outside the thermal insulation layer to form a composite material structure to prevent groundwater from seeping into the thermal insulation layer.


What are the types of steel pipe coatings?

Steel pipes are indispensable in numerous industries for fluid transportation, such as potable water supply systems, HVAC systems, oil and gas pipelines, petrochemical refineries, and agricultural irrigation systems. To ensure their durability and protect against issues like corrosion, manufacturers apply various types of steel pipe coatings. These coatings act as a protective barrier, preventing direct contact between the pipe surface and transported substances, thereby reducing wear and tear and prolonging service life.

Among the widely used steel pipe coating types are galvanized coatings, polyethylene coatings (2LPE/3LPE), fusion-bonded epoxy coatings (FBE coatings), and concrete weight coatings. Each has distinct advantages and applications that make it suitable for different industrial requirements.


1.Polyethylene Coatings (2LPE/3LPE)

Polyethylene coatings, particularly two-layer and three-layer polyethylene coatings (2LPE and 3LPE), are engineered for extreme environments, such as those in the oil and gas industry, petrochemical plants, and underground water pipelines. These coatings provide high resistance to corrosion, impact damage, and shear forces, while also preventing issues like cathodic disbondment. Their versatility and effectiveness make them ideal for pipelines that transport chemicals, crude oil, or drinking water under demanding conditions.


2.Galvanized Coatings

One of the most popular and cost-effective methods of steel pipe corrosion protection is galvanizing. This process typically involves applying a zinc coating, most commonly through hot-dip galvanizing or pre-galvanizing. The metallurgical bond formed between zinc and the steel surface provides robust anti-corrosion properties. Galvanized steel pipes are known for their durability, low maintenance, and cost-efficiency, making them an excellent choice for infrastructure projects like water pipelines and structural supports.


3.Concrete Weight Coatings

Concrete weight coatings are essential for marine pipelines and other underwater applications, particularly in the oil and gas sector. These coatings increase the weight of steel pipes, enabling them to sink to the desired depth and remain stable on the seabed. Beyond adding weight, concrete coatings provide an additional layer of protection to the pipe's exterior, shielding it from marine corrosion, physical impacts, and environmental factors. This makes concrete-coated pipes the preferred choice for projects like offshore crude oil transportation and subsea gas pipelines.


4.Fusion-Bonded Epoxy (FBE) Coatings

FBE coatings are thin, durable layers of epoxy resin that are applied to steel pipes through an electrostatic spraying process. Known for their excellent performance in corrosion resistance, FBE coatings are widely used in industries that require long-term protection, such as natural gas pipelines, water transportation systems, and industrial piping. These coatings are particularly suited for pipeline projects that operate in standard conditions without exposure to highly corrosive or abrasive environments.


Steel Pipe


What is underground coated steel pipe?

Many people often confuse plastic-coated pipes with 3PE anti-corrosion pipes because they look very similar. Plastic-coated pipes, also known as buried plastic-coated steel pipes and steel-plastic composite steel pipes, are organic layers such as modified polyethylene (PE), ethylene-acrylic acid copolymer (EAA), epoxy (EP) powder, non-toxic polypropylene (PP) or non-toxic polyvinyl chloride (PVC) with a thickness of 0.5~1.0mm melted on the inner and outer walls of the steel pipe. This buried plastic-coated steel pipe combines the advantages of steel and plastic. It not only has the advantages of high strength, convenient connection, and water impact resistance, but also eliminates the disadvantages of plastic pipes that are easy to corrode, pollute, scale, and have low strength, and the steel pipe has poor fire resistance in water. It has a long service life and is more economical. The design service life can reach 50 years.

Fire-fighting plastic-coated steel pipe is the most commonly used plastic-coated steel pipe. It uses steel pipe as the base pipe, and the outer wall is sprayed with high adhesion, impact resistance, corrosion resistance and weather resistance thermosetting powder coating, and the inner wall is sprayed with food-grade sanitary thermoplastic powder coating, and then it is post-processed by sandblasting and chemical treatment, preheating, internal coating, external coating, curing, etc.

Application of underground anti-corrosion steel pipe

1. Plastic-coated pipes can be used for various circulating water systems (civilian circulating water, industrial circulating water), fire water supply systems, building water supply and drainage, and urban sewage pipes;
2. Coal mine gas discharge, mud transportation, drainage, ventilation system;
3. Chemical anti-corrosion pipelines transport various chemical fluids, such as acid, alkali and other corrosive media.
4. Used for the protection of buried pipelines and communication cables for wires and cables
5. It can ensure the normal operation of the central air conditioning water circulation system in the central air conditioning HVAC circulation system.

Specifications for underground coated steel pipes

Colors: black, gray, blue, red, white, green;
Coating thickness: PE (modified polyethylene) coating thickness is 400um-1000um, EP (epoxy resin) coating thickness is 100um-400um;
Coating method: hot dip EP, epoxy internal/external spraying;
Specifications: DN15-DN1660;
Ambient temperature: -30℃ to 120℃;
Connection methods: threaded (DN15-DN100), groove (DN65-DN400), flange (suitable for any diameter), welding, bimetallic connection, socket type, pipe joint, sealed connection, etc.


What is plastic-coated steel pipe?

Plastic-coated steel pipe is a steel-plastic composite steel pipe with a steel pipe as the base material, and a plastic anti-corrosion layer is welded on the inner surface (bottom pipe) of the steel pipe through processes such as spraying, rotational molding, dipping, and suction molding, or a plastic anti-corrosion layer is welded on both the inner and outer surfaces.

Plastic-coated steel pipe has excellent corrosion resistance and relatively small friction resistance. Epoxy plastic-coated steel pipe is suitable for water supply and drainage, seawater, warm water, oil, gas and other media, and PVC plastic-coated steel pipe is suitable for drainage, seawater, oil, gas and other media.

Advantages of plastic-coated pipe:

Suitable for buried and humid environments, resistant to high and extremely low temperatures.
Strong anti-interference ability. If plastic-coated steel pipe is used as a cable sheath, it can effectively shield external signal interference.
Good compressive strength, the maximum pressure can reach 6Mpa.
Good insulation performance, as a protective tube for wires, no leakage will occur.
No burrs, smooth pipe wall, suitable for passing wires and cables during construction.


How to choose the right steel pipe coating?

When selecting a steel pipe coating, it’s crucial to consider the service environment, operating conditions, and fluid being transported. For example, galvanized pipes are ideal for general-purpose water pipelines, while polyethylene coatings are better suited for corrosive environments. Fusion-bonded epoxy coatings excel in standard pipeline projects, whereas concrete coatings are indispensable for underwater pipelines.


By understanding the characteristics, advantages, and applications of each type of steel pipe coating, industries can ensure their pipelines remain protected, efficient, and long-lasting. Whether for potable water systems, oil and gas pipelines, or marine applications, the right steel pipe coating is essential for optimal performance.


Steel pipe coatings are classified by material, application, and purpose. Durable coatings like HDPE, FBE, and HPPC are ideal for pipes in oil, gas, and water systems, while galvanization suits smaller structural pipes.


Although bare steel pipes have benefits, protective coatings are essential for broader industrial use. As demand grows, coating technologies will continue evolving to meet industry needs.


BAOWI Steel provides a variety of coating services, including epoxy powder coating (FBE), three-layer polyethylene (3LPE) coating, etc., which are widely used in oil and gas pipelines and industrial fields. Our coating solutions can significantly improve the corrosion resistance, mechanical strength and durability of steel, ensuring the reliability and service life of products in various extreme environments.

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