Carat Structured Wall HDPE Pipe

Spiral Winding Manufacturing — How Carat Pipe Is Made

A high-output extruder feeds a continuous hollow-profile strip (square or rectangular cross-section) onto a heated rotating steel mandrel. As the mandrel rotates and advances longitudinally, the molten profile wraps spirally around it. A secondary extrusion strip is simultaneously applied over the overlapping seams, hot-fusing the spiral coils into a single, seamless pipe wall. The smooth inner liner is co-formed at the same time. This process allows precise control of the profile geometry, enabling custom diameters and ring stiffness values without expensive fixed molds.

Flexible Pipe Physics — Load Sharing with Soil

Rigid concrete pipe must resist the entire applied load (earth cover + traffic) through its wall cross-section alone. When load exceeds the pipe's structural capacity, the wall cracks. A flexible Carat pipe deflects slightly under vertical load. This lateral expansion engages the passive resistance of the compacted soil embedment surrounding the pipe. Through this mechanism, the soil and pipe work together as a composite structural system — the soil carries 80–90% of the applied load, the pipe carries the remainder. Long-term deflection is limited to 5% of inside diameter per ASTM F894 design criteria.

Major Applications

• Metropolitan drainage trunk mains: Managing monsoon stormwater volumes for large urban areas
• Seaport and harbor drainage: Saline-resistant, heavy-load-rated large bore outfall systems
• Airport runway drainage: SN16 stiffness rated for aircraft ground loads; zero-leakage fusion joints
• Power plant cooling water outfalls: Chemical inertness at elevated temperatures
• River flood control infrastructure: Pumping station outfalls, retention pond discharge, river diversions

For smaller diameters (DN150–DN600mm), see our HDPE Dual Wall Corrugated Pipe. For interior building finishes, explore uPVC Ceiling Panels. View all our quality certificates and lab reports.