HDPE Gas Pipe Extrusion Line

This HDPE Gas Pipe Extrusion Line processes PE80 and PE100 grade high-density polyethylene into pressurized natural gas pipelines conforming to ISO 4437 and EN 1555 standards. Engineered for 24/7 continuous industrial operation, the line handles outer diameters from 16 mm to 630 mm across standard dimension ratios (SDR 9, SDR 11, SDR 13.6, SDR 17.6).

The system integrates a high L/D ratio single-screw extruder, a spiral distributor die head, multi-stage vacuum sizing and spray cooling, gravimetric dosing, continuous caterpillar haul-off, and planetary cutting. By maintaining precise thermal control and melt homogeneity, the equipment minimizes internal stress in the extruded pipe, ensuring long-term hydrostatic strength (MRS 10.0 MPa rating for PE100) and strict ovality control required for electrofusion and butt-fusion joining.

Material Feeding & Dosing: PE100/PE80 virgin resin and yellow/black color masterbatch pass through a multi-component gravimetric dosing unit that adjusts screw speed and haul-off rate in real time to maintain pipe weight per meter within ±0.3%.

Plasticization & Extrusion: Material enters a grooved feed barrel where a specialized barrier screw melts resin under controlled shear temperatures (190°C–210°C) to prevent thermal degradation.

Co-Extrusion & Color Line Marking: Melt flows into a spiral distributor die head. A dedicated auxiliary single-screw extruder co-extrudes integrated yellow or orange identification stripes into the pipe's outer layer at the molecular level.

Vacuum Calibration: The extruded pipe blank enters a stainless-steel vacuum chamber (-0.03 to -0.06 MPa). Adjustable bronze calibration sleeves and water jets fix the outer diameter and initial wall geometry.

Multi-Stage Spray Cooling: Sequential immersion/spray cooling tanks lower core temperatures in gradients, eliminating thermal stress and preventing post-cooling wall deformation or sink marks.

Ultrasonic Inspection & Traction: An online 360° ultrasonic scanner calculates wall thickness and concentricity. The multi-caterpillar haul-off pulls the pipe at synchronized speed using vector frequency drives.

Planetary Cutting & Discharge: A chip-free planetary cutter performs square, chamfered cuts synchronized with line speed, discharging straight lengths to a tilting table or small-diameter pipes to a automatic dual-disc coiler.

Main Extruder Unit:
• Screw & Barrel: 38CrMoAla alloy steel, ion-nitrided (depth 0.5–0.7 mm, surface hardness ≥950 HV) or optional bimetallic alloy coating for abrasive resistance.
• Screw Geometry: 33:1 or 38:1 L/D ratio barrier screw with mixing head for low-shear, uniform melt plasticization.
• Drive System: Siemens or SIMO AC motor coupled with a Sunlung/Transcyko high-torque gear reducer featuring an integrated heavy-duty thrust bearing.

Co-Extrusion Die Head:
• Body: 40Cr forged alloy steel with spiral flow channels, mirror-polished and hard-chrome plated internally.
• Striping Extruder: SJ-30/25 single-screw co-extruder for yellow/orange identification lines.
• Heating: Cast aluminum heating zones controlled via multi-channel PID loops.

Vacuum Calibration & Cooling Tanks:
• Material: Full Stainless Steel 304 construction.
• Vacuum System: Dual-chamber 6-meter vacuum tank with independent pressure controls and side-channel pumps.
• Cooling Circuit: 12-meter to 24-meter stainless spray tanks with stainless steel centrifugal pumps and quick-clean spray nozzles.

Haul-Off Unit:
• Configuration: 2-claw, 3-claw, 4-claw, 6-claw, or 8-claw caterpillar configurations based on pipe diameter.
• Control: Individual vector motors with encoder feedback synced via PLC to prevent slippage or pipe deformation.

Cutting & Stacking Equipment:
• Planetary Cutter: Hydraulic clamping, dust-free carbide saw blades, and integrated pipe end chamfering unit.
• Coiler (DN 16–63 mm): Torque-controlled dual-disc coiler with automatic traverse lay-flat winding.

Automation & Electrical System:
• PLC & HMI: Siemens S7-1200/1500 industrial controller with a 10-inch color touchscreen interface.
• Components: Schneider switchgear, ABB frequency inverters, RKC/Omron temperature modules.

Melt Homogeneity at Lower Processing Temperatures: The 38:1 L/D screw design incorporates barrier sections that melt PE100 resin at reduced thermal loads (190°C–210°C). This preserves polymer chain structures and guarantees compliance with ISO 4437 hydrostatic pressure tests (1000h at 80°C / 4.6 MPa).

Closed-Loop Wall Thickness Management: Combining gravimetric feeding with an online ultrasonic scanner keeps wall thickness variance within Δt≤±0.1 mm. Over-gauging is eliminated, reducing raw material usage by 2.5% to 4.0% per shift.

Strict Ovality & Roundness Retention: Multi-stage vacuum regulation (-0.03 to -0.06 MPa) combined with multi-point cooling spray geometries holds pipe ovality within ≤1.2%, ensuring immediate fit-up for field welding.

Pipes manufactured on this equipment meet standard specifications for underground pressurized gas networks:

Natural Gas Mains & Feeder Lines: SDR 11 / SDR 9 pipes operating under pressures up to 10 bar.

LPG & Town Gas Distribution: Residential and industrial fuel gas piping systems.

Biogas Conveyance Systems: Gas transfer lines in agricultural and industrial biogas processing plants.

Compliance Standards: ISO 4437-2, EN 1555-2, ASTM D2513, AS/NZS 4130.

Use the breakdown below to match line sizing with target production requirements:

Every line undergoes a two-stage inspection process prior to factory acceptance and packing:

Stage 1: Static Assembly & Electrical Audit
Mechanical alignment checks via precision laser leveling across frame bed tracks.
Dynamic balancing verification of drive shafts, gearbox input/output couplers, and cutter heads.
Electrical safety test verifying insulation resistance (>10 MΩ) and grounding continuity.

Stage 2: 8–12 Hour Continuous Factory Acceptance Test (FAT)
Equipment runs on PE100 raw material at maximum operating speed. Acceptable operating parameters must meet the following metrics before customer sign-off:
• Melt Pressure Stability: Pressure fluctuation at the die head kept within ±0.8 MPa.
• Thermal Drift: Barrel temperature variations maintained within ±1.0∘C across all zones.
• Weight Accuracy: Extrusion weight variation across 6 timed pipe samples held within ≤±1.5%.
• Vibration Limits: Gearbox bearing housing vibration velocity remains below 2.5 mm/s.

In-House Precision Machining: Components such as barrels, dies, and frames are processed using CNC machine tools, laser cutting centers, and dynamic balancing equipment to maintain strict tolerance control.

Standardized Spare Part Availability: Critical wearing parts (heater bands, thermocouples, pressure transducers, seals, and cutter blades) are maintained in stock to support dispatch within 60 days for standard orders.

Engineering Field Support: Technical assistance includes layout engineering, power line planning, overseas installation supervision, material formulation adjustment, and machine operator training.

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