Overview
Extruded polyethylene coating is a thermoplastic polymer layer applied through extrusion technology, commonly used to protect metal substrates from corrosion, abrasion, and environmental stress. The process involves melting polyethylene resin and forming it into a continuous, uniform coating around pipes, cables, or structural components. This coating is favored for its combination of mechanical durability and chemical inertness, making it suitable for harsh environments. Industry standards such as ISO 21809-1 and CSA Z245.21 define quality parameters for extruded PE coatings in pipeline applications.
Physical and Chemical Properties
The coating exhibits low density (0.91–0.96 g/cm³) depending on whether LDPE, MDPE, or HDPE is used, with tensile strength ranging from 8–30 MPa. Its water absorption rate is <0.01%, ensuring long-term moisture resistance. Chemically, it resists acids, alkalis, and salts but may swell in aromatic hydrocarbons. The dielectric constant (2.2–2.4) makes it effective for electrical insulation. UV-stabilized formulations maintain properties for over 20 years in outdoor exposure.
Main Applications
Over 60% of extruded PE coatings are used in oil/gas pipelines, providing corrosion protection for buried or submerged steel pipes. In construction, it safeguards rebar and structural steel, while telecom cables utilize its insulation properties. Emerging applications include marine infrastructure (e.g., dock pilings) and agricultural equipment coatings. Multi-layer systems combining epoxy primer with PE topcoats offer enhanced performance for critical infrastructure projects.
Safety and Storage
While polyethylene is non-toxic, processing temperatures (150–300°C) may release volatile compounds requiring ventilation. Finished coatings are food-contact approved (FDA 21 CFR 177.1520) when formulated without additives. Storage should avoid direct sunlight to prevent UV degradation before application. Bulk resin pellets are typically stored in moisture-proof containers at <40°C. Fire risks are moderate (autoignition ~350°C).
B2B Procurement Guide
Key specifications include coating thickness (usually 1–5 mm), adhesion strength (>50 N/cm), and impact resistance (>5 J/mm). For pipelines, cathodic disbondment tests (e.g., ISO 21809-1) are critical. Suppliers should provide mill test reports with melt flow index (MFI) data (typically 0.1–5 g/10min). Large projects often require third-party inspection of application processes. MOQs for custom formulations start at 5–10 metric tons.
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