Analysis of Process Parameters for Different Material Pairs of Mechanically Lined CRA Pipes Manufactured by Thermal-Hydraulic Expansion Process

Mechanically lined corrosion resistant pipes are produced by establishing a sufficiently high residual contact pressure (gripping force) between a corrosion resistant liner and a steel outer pipe. The most effective way to achieve such high contact pressure is by the thermal-hydraulic expansion manufacturing process. In this study, simulation of the thermal-hydraulic expansion process of mechanically lined corrosion resistant pipes is performed using the finite element method. The effects of process parameters such as process temperature, hydraulic pressure, and cooling rates for different material pairs of mechanically lined corrosion resistant pipes are investigated. Results reveal that both the water- and air-cooling rates have negligible influence on the magnitude of residual contact pressure. The furnace temperature is proved to be the governing factor to obtain high residual contact pressure for the material pairs N08825/X65 and N08031/X65. However, for the material pair 304/X65, increasing the temperature difference by reducing the hydraulic loading and unloading time durations as much as possible is the most effective way to increase the residual contact pressure.