AntiStatic I Antistatic composite piping systems: Efficient and cost-effective manufacturing process for various applications

Antistatic composite piping systems are already being used for transporting fluids in applications where corrosion and the weight of metallic systems are issues and electrical charging must be avoided. However, the wet-winding process currently in use is restricted to straight pipe sections only and does not provide any scalability. Therefore, a limited freedom of design as well as high production costs restrict the application of this technology to a few industries. By combining two established composite processing technologies – PulBraiding for the straight pipe sections and braiding RTM for the curved pipe sections – these disadvantages can be overcome.
Figure 1 shows the concept of the currently used technology in comparison to the novel technology developed in AntiStatic.

Furthermore, to assess the complete potential of the innovative manufacturing technology, a life cycle and cost analysis is conducted to achieve ecological and economic balance throughout the entire process chain and identify areas for optimization.

The task assigned to the Fraunhofer IGCV is to develop the PulBraiding process for producing the straight sections of the antistatic piping system as well as conducting the Life Cycle Assessment during the production phase. PulBraiding (see figure 2) offers a cost and energy efficient manufacturing process as well as the opportunity to add continuous off-axis reinforcement during the pulling process.

The composite piping systems (see figure 3) must meet specific requirements regarding the electrical conductivity to be suitable for a use in the aviation sector. On one hand, the conductivity needs to be low enough to prevent the risk of inflammation in the event of a lightning strike. On the other hand, the conductivity needs to exceed a certain threshold to prevent the accumulation of electrostatic charges due to the flow of liquids through the pipes.

The antistatic properties of the pipes can be achieved by modifying the respective resin system with conductive filler materials. In AntiStatic the specific resistance is reduced to the required range by adding MIRALON® pulp (Huntsman Advanced Materials). During the production of MIRALON® pulp, the greenhouse gas methane is converted into hydrogen and the resulting carbon-based structure. While the hydrogen can be recycled as fuel, the MIRALON® pulp is utilized as a filler material to enhance various properties, particularly the electrical conductivity.

One of the greatest challenges is to achieve a uniform distribution of the MIRALON® pulp. The goal is to achieve isotropic antistatic properties, despite the anisotropic fiber structure during processing. Antistatic properties are particularly important during the transport of high-energy fluids as even a minimal spark formation due to electrostatic discharges can lead to explosions.

In AntiStatic, the aim is to develop a demonstrator for an application in the civil aviation. For this purpose, a piping system consisting of straight and curved pipe sections connected by an innovative pipe connection concept is developed.