Analysis of 3PE anti-corrosion pipeline manufacturing process

3PE anti-corrosion steel pipe base materials include seamless steel pipes, spiral steel pipes, and straight seam steel pipes. The three-layer polyethylene (3PE) anti-corrosion coating has been widely used in the oil pipeline industry due to its good corrosion resistance, water vapor permeability resistance, and mechanical properties. The anti-corrosion layer of 3PE anti-corrosion steel pipes is crucial to the life of buried pipelines. Some pipelines of the same material will not corrode after being buried underground for decades, while others will leak within a few years. This is because they use different external anti-corrosion layers.

Anti-corrosion structure
The outer wall anti-corrosion form of steel pipe, 3PE anti-corrosion generally consists of 3 layers of structure:
The first layer of epoxy powder (FBE>100um)
The second layer of adhesive (AD) 170~250um
The third layer of polyethylene (PE) 2.5~3.7mm
In actual operation, the three materials are mixed and integrated into one, and after processing, they are firmly combined with the steel pipe to form an excellent anti-corrosion layer. Its processing methods are generally divided into two types: winding type and round die covering type.

3PE anti-corrosion steel pipe coating, also known as (three-layer polyethylene anti-corrosion coating), is a new anti-corrosion coating that cleverly combines the 2PE anti-corrosion layer in Europe and the widely used epoxy powder anti-corrosion steel pipe coating (FBE) in North America. Steel pipe coating. It has been recognized and used around the world for more than ten years. The coating of 3PE anti-corrosion steel pipe is that the bottom layer is in contact with the steel pipe surface and is an epoxy powder anti-corrosion coating, and the middle layer is a copolymer adhesive with branched structural functional groups. The surface layer is high-density polyethylene anti-corrosion coating. 3PE anti-corrosion coating combines the high impermeability and high mechanical properties of epoxy resin and polyethylene materials. So far, it is a pipeline anti-corrosion coating recognized globally for its effectiveness and performance and has been used in many projects.

Standard setting
In the early days of introducing 3PE coating technology, China Petroleum Engineering Technology Research Institute compiled China's 3PE coating construction acceptance specifications concerning DIN30670-1991 and NFA49-710 (March 1988 edition) in April 1995, which were used for Shaanxi-Beijing pipelines, Kuang-Shan pipeline construction. In the same year, it was upgraded to the industry standard SY/T4013-1995. After several years of engineering construction summary and practice, it was revised to SY/T0413-2002 in 2001 and implemented on August 1, 2002. At the beginning of the establishment of the standard, according to the actual situation in China, polyethylene was mainly high-density polyethylene, and the Vicat softening point was set to not less than 110°C; the thickness of the outer anti-corrosion layer was based on German standards, which were mainly low- and medium-density polyethylene. DIN30670-1991 to determine. It greatly improves the impact strength of the 3PE anti-corrosion layer and ensures the construction quality of the Shaanxi-Beijing pipeline and the Kushan-Shanxi pipeline. SY/T0413-2002 also greatly improves the peeling strength and impact resistance indicators of the 3PE anti-corrosion layer and stipulates According to the carbon black content of some special materials, the mechanical strength and weather resistance of the 3PE anti-corrosion layer are guaranteed, and the frequency of spot testing of the patching peel strength (that is, the peel strength of the heat shrink sleeve and heat shrink tape against the primer steel) is increased. Contributed to ensuring the quality of the anti-corrosion coating outside the pipeline.

Project application
At present, 3PE anti-corrosion has successfully solved the problem of corrosion resistance and bump resistance of the outer wall of steel pipes. However, liquid epoxy coating IPN8710 is usually used for inner wall anti-corrosion in China. This liquid epoxy takes a long time to solidify at room temperature, and the inner wall adopts a liquid ring. Oxygen coating can only reduce drag, but cannot achieve corrosion resistance and erosion resistance. If used in water pipelines, the inner wall must be in the form of thermally fused epoxy resin powder to better improve the corrosion resistance and resistance of the inner wall. Friction ability. Among them, the 3PE outer 3PE inner sintered epoxy composite steel pipe used in the Henan section of the middle line of the South-to-North Water Diversion Project has been successfully used in the South-to-North Water Diversion Project. It solves the problem that the inner wall is not easy to scale, smooth, wear-resistant, and corrosion-resistant.