Coilable Dual Wall Corrugated Pipe
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Solution Overview
Problem
Conventional dual wall corrugated HDPE pipes lack longitudinal flexibility, preventing them from being coiled or flexed without breakage, which limits installation efficiency and requires costly open trench excavations in agricultural applications where high flow capacity and rapid installation are crucial.
Innovation Solution
The inner liner wall of the pipe is modified with a material having enhanced strain capacity and reduced modulus of elasticity, such as linear low density polyethylene (LLDPE) or a thermoplastic elastomer (TPE) additive, to promote flexibility and resiliency, allowing the pipe to be coiled and plowed into the ground without failure, while maintaining sufficient axial strength for bell and spigot coupling systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If dual wall corrugated HDPE pipe uses conventional HDPE material for the inner liner wall, then axial strength is maintained, but longitudinal flexibility is insufficient preventing coiling
Solution Approach 1:
The inner liner wall is constructed from a composite material combining HDPE and an elastomeric polymer (such as polyethylene copolymer, polypropylene copolymer, or thermoplastic elastomer). This composite provides both the axial strength of HDPE and the longitudinal flexibility of the elastomeric component, enabling the pipe to be coiled while maintaining structural integrity.
Solution Approach 2:
The material composition of the inner liner wall is modified by changing the polymer blend ratio, typically comprising 20-80% elastomeric polymer and 80-20% HDPE. This parameter adjustment optimizes the balance between axial strength and longitudinal flexibility, allowing the pipe to achieve coilable flexibility while maintaining sufficient axial stiffness for bell and spigot coupling systems.
2Adaptability or versatility
If single wall corrugated HDPE pipe is used, then longitudinal flexibility and coilability are achieved, but hydraulic efficiency is poor due to rough interior surface
Solution Approach 1:
The pipe is segmented into two distinct wall structures: an outer corrugated wall for structural strength and an inner smooth liner wall for hydraulic efficiency. This segmentation allows each wall to perform its specialized function independently, with the smooth inner liner providing a Manning's coefficient of 0.010-0.015 while the outer corrugated wall maintains axial stiffness.
Solution Approach 2:
Different surface qualities are applied to different parts of the pipe structure. The inner liner wall is designed with a smooth surface quality to minimize friction and maximize flow capacity, while the outer wall maintains the corrugated quality necessary for structural integrity and flexibility.
3Productivity
If dual wall corrugated HDPE pipe is used, then hydraulic efficiency improves, but longitudinal flexibility is reduced preventing automated installation
Solution Approach 1:
The inner liner wall uses a composite material system combining HDPE with 20-80% elastomeric polymer content. This composite provides the longitudinal flexibility needed for automated plowing installation while maintaining the smooth surface required for hydraulic efficiency and a Manning's coefficient of 0.010-0.015.
Solution Approach 2:
The material composition parameters of the inner liner are optimized to achieve a balance between flexibility and smoothness. By controlling the elastomeric polymer content within 20-80% and adjusting molecular weight and density parameters, the pipe achieves both coilability for automated installation and hydraulic efficiency for high flow capacity.
Data Source
AI summary
High flow capacity corrugated coilable dual wall plastic pipe having improved longitudinal flexibility and a bend radius sufficient to permit coiling and plowing of such pipe into the ground using automated installation equipment. The coilable dual wall pipe has an outer corrugated wall formed of a thermoplastic material such as high density polyethylene, and an inner smooth wall formed of a different more flexible and resilient thermo-bondable material that has an enhanced strain capacity and lower modulus of elasticity. The inner wall material also has enhanced mechanical properties which generally improve processing and help prevent excessive drag and tearing of the liner material during the manufacturing process. Suitable material blends for the inner wall incorporating a thermoplastic elastomer additive in combination with a thermoplastic material have proven suitable in providing the required longitudinal flexibility and pipe bend radius to permit the desired pipe coiling and plow installation without failure.