3PE Anti-Corrosion Production Process

Product Introduction

The base pipes for 3PE anti-corrosion coating include seamless steel pipes, spiral steel pipes, and longitudinal seam steel pipes.
The three-layer polyethylene (3PE) anti-corrosion coating is widely used in the oil and gas pipeline industry due to its excellent corrosion resistance, water vapor permeability resistance, and mechanical properties. The anti-corrosion coating is crucial for the service life of buried pipelines. Pipelines of the same material can have vastly different lifespans; some remain uncorroded for decades underground, while others leak within a few years, primarily due to differences in the external anti-corrosion coating applied.

Coating Structure

The 3PE coating generally consists of a three-layer structure:

   First Layer: Epoxy Powder (FBE), >100 µm

   Second Layer: Adhesive (AD), 170~250 µm

   Third Layer: Polyethylene (PE), 1.8~3.7 mm

In practice, these three materials are integrated into a single unit through processing, forming a robust bond with the steel pipe to create an excellent anti-corrosion layer. The processing methods typically include the wrap-around method and the side-wrap method (round die encapsulation).

Coating Technology

The 3PE anti-corrosion steel pipe coating is a innovative combination of the European 2PE anti-corrosion layer and the Fusion Bonded Epoxy (FBE) coating widely used in North America. This composite coating has been recognized and used globally for over a decade.

The coating structure consists of

   Bottom Layer: An epoxy powder anti-corrosion coating in direct contact with the steel pipe surface.

   Middle Layer: A copolymer adhesive featuring branched functional groups.

   Top Layer: A high-density polyethylene (HDPE) anti-corrosion coating.

The 3PE coating combines the high anti-permeability and superior mechanical properties of epoxy resin and polyethylene materials. It is globally recognized as the most effective and highest-performing pipeline anti-corrosion coating available today, leading to its widespread use in numerous projects.

Execution Standard

The domestic standard implemented in China is SY/T0413-2002, effective from August 1, 2002. This standard primarily specifies the use of polyethylene (PE) and high-density polyethylene (HDPE). The Vicat softening point is defined as not less than 110°C. The thickness of the external anti-corrosion layer is determined based on the German standard DIN 30670-1991, which primarily uses low and medium-density polyethylene, significantly enhancing the impact strength of the 3PE coating.

SY/T0413-2002 substantially increased the indicators for peel strength and impact resistance of the 3PE coating. It clearly specifies the carbon black content for certain dedicated materials, ensuring the mechanical strength and weather resistance of the 3PE coating. It also increased the sampling frequency for testing the peel strength of field joint coatings (i.e., the peel strength of heat-shrink sleeves or tapes onto the primer-coated steel).

Applications

  The applications of 3PE anti-corrosion steel pipes are extensive and often not fully appreciated. They are suitable for:

   Water supply and drainage networks in coal mine shafts.

   Underground shotcrete, positive/negative pressure ventilation, gas drainage, and fire water spray pipelines in mines.

   Process water, slag, and return water transmission pipelines in thermal power plants. They are particularly suitable for water supply pipelines in spray/sprinkler systems.

   Cable protection conduits for power, communications, and highways.

   Water supply pipelines in high-rise buildings, hot water networks for heating, water supply projects, gas transmission, and buried water transmission pipelines.

   Petroleum transmission pipelines, and process pipelines for conveying corrosive media in industries like chemical, pharmaceutical, and dyeing.

   Sewage discharge pipes, sewer pipes, and anti-corrosion projects for biological tanks.

   Agricultural irrigation pipes, well casing pipes, drainage pipes, and other network applications.

In essence, 3PE anti-corrosion steel pipes are indispensable in current construction projects. It is believed that with technological advancements, they will achieve even more brilliant accomplishments in the future.