Ningbo Fangli Technology Co., Ltd. is a mechanical equipment manufacturer with over 30 years’ experiences of plastic pipe extrusion equipment, new environmental protection and new materials equipment. Since its establishment Fangli has been developed based on user’s demands. Through continuous improvement, independent R&D on the core technology and digestion & absorption of advanced technology and other means, we have developed PVC pipe extrusion line, PP-R pipe extrusion line, PE water supply / gas pipe extrusion line, which was recommended by the Chinese Ministry of Construction to replace imported products. We have gained the title of “First-class Brand in Zhejiang Province”.
01 Why PE-RT Leads the Floor Heating Pipe Market
PE-RT (Polyethylene of Raised Temperature Resistance) has quickly become a preferred material for building hot water systems and radiant floor heating. Compared with traditional PE pipes, PE-RT offers superior long-term hydrostatic strength, better thermal stability, greater processing flexibility, longer service life, and heat-fusion joint capability. It is also fully recyclable, aligning with green building trends.
As the floor heating market expands, pipe manufacturers are under pressure to boost both output and efficiency. Many are turning to high-speed extrusion lines, which run at 15–25 m/min—more than double the speed of conventional lines (5–6 m/min). This shift not only doubles throughput but also reduces factory floor space, lowers labor costs, and simplifies process control for better product consistency. Moreover, high-speed extrusion consumes less energy per kilogram of output. With fewer machines and higher efficiency, manufacturers gain the agility to fulfill orders faster, reduce inventory, and accelerate capital turnover.
02 Process Control: Temperature Matters, Material Quality Counts
A typical PE-RT pipe production line follows this workflow:
Raw material drying → Extruder heating → PE-RT die forming → Vacuum sizing → Cooling and shaping → Printing → High-speed haul-off → Chipless cutting → Coiling → Inspection → Packaging → Pressure testing → Final packing → Warehousing.
Commonly used PE-RT grades include DOWLEX 2344/2388E (Dow), YUCLAIR DX800/DX900 (SK), SP980 (LG), XP 9000 (Daelim), and domestic QHM22F (Qilu). These materials behave differently under high-speed conditions, so consistent raw material sourcing and quality control are non-negotiable.
Temperature is the most critical variable. The optimal processing window for PE-RT is 180–210 °C. Lower temperatures lead to poor plasticization, dull surfaces, or melt fracture; higher temperatures soften the parison excessively and may cause surface ripples. In practice, temperature should be kept within ±5 °C—larger swings can affect wall thickness and mechanical performance.
03 Equipment Selection: Precision Enables Speed
Floor heating pipes are typically coiled in 200–300 meter lengths. Any hidden defect in the middle may go unnoticed but can become a failure point during service. That's why high-speed production demands precision equipment capable of faithfully transferring the material's inherent properties to the finished product.
Most high-speed lines are built around a Φ65 mm extruder, delivering up to 250 kg/h at stable speeds of 15–25 m/min. Given PE-RT's relatively high melt viscosity, the extruder must provide high torque, imported thrust bearings, and specially hardened alloy gears to reduce noise and heat. Advanced automation ensures safe, stable operation.
During processing, poor control over melting, parison formation, or cooling can lead to degradation, molecular orientation, or internal stresses. Therefore, the system should follow three principles: low melt temperature to avoid degradation, homogeneous melt to prevent molecular chain orientation, and uniform cooling to reduce internal stress.
04 Screw and Barrel Design: Where Homogenization Begins
PE-RT requires a screw with a length-to-diameter (L/D) ratio of 33:1, featuring a two-stage mixing design with mixing sections both mid-barrel and near the tip. This ensures thorough plasticization without excessive shear. The feed zone uses an independent bushing with axial grooves and cooling, which significantly improves solids conveying.
Both screw and barrel are made of high-grade alloys with specialized surface treatments. Precision machining is critical—any surface irregularities can cause material stagnation, leading to thermal degradation and intermittent black specks on the pipe surface over time.
05 Die Head Design: Tailored for PE-RT
Conventional spider-type dies often introduce weld-line defects and are not ideal for PE-RT. Today, spiral-flow dies are widely used, with drawdown ratios typically between 1.3 and 1.6. The smoothness of the die lip and mandrel directly affects pipe appearance—scratches, false cracks, or melt buildup can become failure initiation points under long-term thermal and pressure cycling.
We have developed a PE-RT-specific die head that addresses these issues. The melt enters through a star-shaped divider, splits into multiple streams, and is recombined via a spiral distributor to form an annular flow. After passing through a filtration stage and gradual compression, it exits through the die lip. This multi-stage process ensures excellent homogenization and enables "low-temperature, low-pressure" extrusion, minimizing shear-induced degradation—ideal for high-speed production.
06 Cooling and Sizing: Speed Demands Smart Cooling
The overall layout of a PE-RT line resembles that of standard polyolefin lines, but the cooling and sizing section is where key differences emerge.
Due to PE-RT's high melt viscosity, a pre-cooling ring is installed ahead of the sizing sleeve to assist parison entry. PE-RT also has high enthalpy, requiring longer cooling zones—typically over 23 meters in total, including one vacuum tank and two water troughs, to adequately cool 20×2.0 mm pipe at speeds above 15 m/min.
For the sizing sleeve, a disc-type water-curtain design is preferred over conventional water-film types. The latter tends to cause surface roughening or even pipe breakage during extended runs, whereas the disc-type design provides effective pre-cooling and prevents material adhesion at the inlet, ensuring smooth, continuous operation.
07 Key Takeaways
Achieving high-speed, high-quality PE-RT pipe extrusion is a systems-level challenge. It requires precision machinery and tooling, optimized screw and die designs, effective cooling strategies, rigorous process control, and consistent raw material quality—all working together.
When these elements align, manufacturers gain significant productivity gains, lower unit costs, and the ability to offer competitively priced products without compromising quality. As demand for energy-efficient heating solutions continues to rise, high-speed PE-RT extrusion technology will play an increasingly vital role in meeting global market needs.
For more information or technical consultation on PE-RT pipe extrusion lines, please contact Ningbo Fangli Technology Co., Ltd.—we are here to support your production goals with professional expertise and tailored solutions.