3PE coating, or three-layer polyethylene coating, is a widely used method of coating pipes and other metal surfaces to protect them from corrosion and other forms of damage. This coating is made up of three layers - an inner layer of epoxy, a middle layer of adhesive, and an outer layer of polyethylene.3PE coating, or three-layer polyethylene coating, is a widely used method of coating pipes and other metal surfaces to protect them from corrosion and other forms of damage. This coating is made up of three layers - an inner layer of epoxy, a middle layer of adhesive, and an outer layer of polyethylene.
3PE pipe manufacturing process
The manufacturing process of 3PE pipe mainly includes the following steps:
1. Steel pipe surface treatment: First of all, it is necessary to perform surface treatment on the steel pipe to remove rust, oil and other impurities, and improve the roughness of the steel pipe surface to make the adhesion of the subsequent coating.
2. Polyethylene dry coating: The active amount of polytalene adhesive is coated on the surface of the steel pipe, and the material mixture is formed on the surface of the steel pipe through the drying and internalization process. The main function of the bonding layer is to closely bond the surface of the anti-corrosion chamber steel pipe in the middle layer.
3. Polyethylene anti-corrosion coating: On the basis of the bonding room, the polyethylene anti-corrosion coating is evenly sprayed on the surface of the steel pipe through special spraying equipment to form the anti-corrosion layer of the middle layer. The polyethylene anticorrosive layer has good corrosion resistance and can effectively isolate the contact between the steel pipe and the external environment, so as to prevent the corrosion of the steel pipe.
4. Polyethylene protective layer spraying: The last step is to spray a layer of polyethylene protective layer on the surface of the polyethylene anti-corrosion layer to protect the anti-corrosion layer of the middle layer from the damage of the external environment. The thickness of the polyethylene protective layer is usually slightly thinner than that of the polyethylene anti-corrosion layer, but it has better mechanical strength and wear resistance.
What are the three layers of 3PE ?
3PE coating of steel pipes is an innovative and proactive method of ensuring that steel pipes remain durable and resistant to corrosion. This is a coating system that involves the application of three layers of protective coating on the surface of steel pipes.
- Firstly, there is a layer of epoxy primer that acts as an adhesive between the steel surface and the other layers. It is important to note that the epoxy prmer provides excellent adhesion to the steel surface and ensures that the other layers adhere to the steel surface properly.
- Secondly, the layer of adhesive is applied to the epoxy primer, and its main function is to facilitate the bonding of the topcoat and the inner layer of the coating. It should be noted that the adhesive layer also provides excellent corrosion protection properties that help to keep the steel pipe protected from corrosion.
- Finally, the third layer is the polyethylene topcoat, which is the outer layer of the coating. It provides excellent protection against mechanical damage and UV rays. Furthermore, it is this layer of coating that gives the steel pipe its distinctive look.
COLOR
The color of 3PE anti-corrosion steel pipe is usually black, because its outer layer is high-density polyethylene (HDPE), and polyethylene itself is translucent or opaque white to off-white solid. However, according to different application requirements and specifications, 3PE anti-corrosion steel pipes may also have other colors of coating, such as yellow, red or other colors.
3PE Coating Thickness
1. The first layer of epoxy powder (FBE) : greater than 100 microns (μm).
2. The second adhesive (AD) : 170 ~ 250 microns (μm).
3. The third layer of polyethylene (PE) : the ordinary grade is 1.8 ~ 2.2 mm (mm), and the strengthening grade is 2.5 ~ 3.7 mm (mm).
Specific to different diameters of steel pipes, the minimum thickness of 3PE coating is as follows:
(Nominal diameter)DN ≤ 100mm: epoxy coating 60 ~ 80μm, adhesive layer 200 ~ 400μm, the minimum thickness of ordinary anti-corrosion layer 1.8mm, reinforced 2.5mm.
-100mm < DN ≤ 250mm: ordinary type 2.0mm, enhanced type 2.7mm.
-250mm < DN ≤ 500mm: 2.2mm for ordinary type and 2.9mm for enhanced type.
-500mm < DN < 800mm: 2.5mm for ordinary type and 3.2mm for enhanced type.
- DN ≥ 800mm: 3.0mm for normal type and 3.7mm for enhanced type.
Advantages of 3PE coating
3PE coating, that is, three layers of polyethylene coating, offers the following advantages:
- Good corrosion resistance: 3PE coating can effectively prevent pipeline corrosion, which is particularly important in the oil pipeline industry.
- Permeability resistance:
The 3PE coating has good permeability resistance, and the water only penetrates into the surface layer, and there is no water in the inner layer, so that the pipeline is well protected. The results show that the 3PE anticorrosive layer absorbs water faster in acidic environment than neutral and alkaline environment, but it is difficult to react even under acidic conditions with pH=5. The 50-day accelerated test does not reduce the binding force between the base steel and the 3PE anticorrosive layer.
- Cathode stripping resistance:
3PE coating has good cathode stripping resistance, which means that under cathodic protection conditions, the coating is not easy to peel, thereby protecting the pipeline from corrosion.
- Mechanical damage resistance:
3PE coating has good mechanical properties and insulation properties, and can resist mechanical damage, such as bump damage, which is particularly important in the transportation and construction process of pipelines.
- Good sealing:
The sealing performance of 3PE coating is good, long-term operation can save energy, reduce costs and protect the environment.
- Strong corrosion resistance:
3PE coating has strong corrosion resistance, easy construction, and service life of up to 30-50 years.
- Good low temperature performance:
Under low temperature conditions, 3PE coating also shows good corrosion resistance and impact resistance, and polyethylene water absorption is low.
- Comprehensive anticorrosive performance:
3PE coating integrates the interface characteristics and chemical resistance of fused epoxy powder coating, combined with the mechanical protection characteristics of extruded polyethylene anticorrosive layer, and integrates the high impermeability and high mechanical properties of epoxy powder and polyethylene. It is currently a globally recognized pipeline anticorrosive coating with good effect and good performance.
- Resistance to microbial erosion:
3PE coating also has the characteristics of resistance to microbial erosion, which can prevent bacteria and microorganisms in the soil from eroding the tube body, resulting in the possibility of failure and stripping of the anti-corrosion layer.
- Strong adhesion with the steel pipe:
The adhesion between the 3PE coating and the steel pipe is strong, which helps the coating to remain stable on the surface of the pipe and is not easy to fall off, enhancing the overall anti-corrosion effect of the pipe.
- Long service life:
According to relevant information, the three-layer PE can make the life of the buried pipeline reach 50 years, which is considered to be the most advanced pipeline external corrosion prevention technology.
- Good impact resistance: 3PE coating has good impact resistance, can withstand a certain external impact, protect the pipeline from damage.
- Flame retardant and antistatic properties: 3PE coating has good flame retardant and antistatic properties.
- Simple construction:
Polyethylene pipe is light in weight, easy to handle, simple in construction, low in comprehensive project cost, and has significant economic benefits.
- Strong environmental adaptability: 3PE coating is suitable for a variety of environments, including cold zones and areas with developed plant roots.
