Pre-Insulated Pipe Plastic PE HDPE LDPE Thin Wall Casing Pipe Extruder Machine

gas/oil /water pipeline Puf Pre-Insulated Pipe PE shell casing plastic Machinery

HDPE Jacket Pipe Extrusion Line is high-efficient with high speed and energy saving for producing HDPE thin wall pipe, which is used as a protective cover of PU foam thermal Pre-insulated Pipe according to international standard.
The HDPE jacket pipe is produced by vacuum calibrating method with smooth internal and external wall, long service life, good anti-corrosion insulation and mechanical performance.

Technical Prameters:

HDPE Jacket Process Flow:

1. Vacuum Feeding of PE Granules: The raw PE granules are automatically fed into the system via vacuum suction.
2. Hot Air Drying: The granules are dried using hot air to remove moisture, ensuring optimal extrusion quality.
3. Extrusion Plasticizing: The dried granules are plasticized through the extruder, heated and mixed to form a molten plastic mass.
4. Mold Shaping: The molten plastic is shaped into the desired pipe profile by passing through the extrusion die.
5. Vacuum Sizing: The pipe is then subjected to vacuum sizing, adjusting its dimensions to precise specifications.
6. Water Cooling: The pipe is cooled rapidly by immersion in a water tank to solidify its shape and structure.
7. Pulling Out: The solidified pipe is pulled out of the cooling tank at a controlled speed.
8. Cutting: The pipe is cut to the desired length using a precision cutting machine.
9. Carrier Laying-off: The cut pipes are then neatly laid off onto a carrier for further handling or packaging

The production steps of the insulation layer for a pre-insulated pipe, specifically focusing on the polyurethane (PU) foam insulation, are outlined below in detail:

1. Formation of the Casing Structure:
   • The steel pipe is first inserted into the high-density polyethylene (HDPE) outer protection pipe, creating a casing structure.
   • Supports are evenly arranged in the annular space between the steel pipe and the HDPE outer pipe to maintain a uniform distance and prevent the two pipes from touching directly.
   • The two ends of the casing are sealed with flanges to ensure that the polyurethane foaming material will be contained within the space during the injection process.
2. Preparation of the Steel Pipe Surface:
   • Prior to the injection of the insulation material, the surface of the steel pipe undergoes pre-treatment such as shot blasting or blast cleaning. This step removes any impurities, rust, or scale, providing a clean and suitable surface for optimal adhesion of the polyurethane insulation.
   • Additionally, corona treatment of the polyethylene pipe shell's surface may also be performed to enhance its adhesion properties.
3. Injection of Polyurethane Foaming Material:
   • The casing structure is hoisted onto a foaming platform specifically designed for this purpose.
   • A high-pressure foaming machine is used to inject the polyurethane foaming material into the casing. The material expands and fills the entire annular space between the steel pipe and the HDPE outer pipe.