Sjoerd Jansma，Suzanne van Greuningen – Kiwa Technology, Apeldoorn, The Netherlands

HZ info，Peter Cloos – SoluForce, Enkhuizen, The NetherlandsThis paper describes the tests and the model used to define the behavior of a reinforced thermoplastic pipe (RTP) in terms of chemical resistance and permeation to carbon dioxide.

Carbon dioxide has a high solubility compared to other media, such as nitrogen and methane, for most materials. The main product properties that this high solubility can affect are:

The chemical compatibility of the materials, in particular the resistance to rapid gas decompression (RGD). During a rapid decompression event, absorbed gases in the polymer can expand rapidly, resulting in blistering and cracking of the material.

The permeation rate of the RTP. The permeability coefficient depends on both the diffusivity and the solubility of the permeant in the material. A high solubility can therefore result in a high permeability. The resistance to RGD of a HDPE liner is demonstrated by submerging test pieces in supercritical CO2 at 156 bar and 65 °C and quickly reducing the pressure to atmospheric conditions for 20 cycles. The test shows no formation of blisters, or slitting, or other defects.

The permeation rate of the RTP is determined by two different methods. The first method uses the permeation properties of each material in each layer, which are combined in a model to estimate the overall permeation rate. Some of the parameters were first determined in a separate permeation experiment. The second method consists of a full-scale permeation test of the product at 40 bar and 65°C using gaseous CO2. The latter measurement is used to validate the previous model, providing an overall understanding of the product’s performance.

The results presented in this paper show that RTPs are a mature product and are able to compete with steel pipes for the transport of carbon dioxide at high pressure and temperature, making them an excellent alternative as piping system for CCUS.