Ring-stiffness evaluation and optimization of structured-wall PE pipes

Structured-wall high density polyethylene pipes up to 3m diameter are used extensively in civil engineering applications including storm water attenuation tanks, culverts, surface drainage, inter-process pipe work, sewers etc. The pipes are manufactured by extruding a hollow box section which is wound in a spiral manner onto a mandrel with successive turns welded together using PE from an auxiliary extruder. A key quality control measure is the ring stiffness to BS EN 1446: 1996. The ability to predict this accurately as a function of the pipe wall geometry is a pre-requisite for optimization of the pipe design. The paper describes the development and the validation of finite element modeling of the ring stiffness test in comparison with experimental results, and considers the relationship between the test results and in-situ performance. Approaches to optimizing the pipe wall structure are also outlined.