Fiber-jacketed creep resistant pipes for high-temperature applications
Maximilian Friedrich, Andreas Klenk, Stefan Weihe
Materials Testing Institute (MPA) University of Stuttgart
The challenge of decarbonizing electricity generation and process industries poses significant materials-related challenges. The pursuit of higher process temperatures for enhanced efficiency, coupled with increasingly demanding requirements for flexible operation, necessitates the exploration of innovative material concepts. Traditional martensitic steels, commonly employed thus far, prove to be inadequate for process temperatures surpassing 650 °C. While austenitic steels and nickel-based alloys permit higher temperatures, they demand substantial wall thicknesses, incurring both manufacturing expenses and susceptibility to thermally induced fatigue during cyclical operation. Addressing these challenges is the concept of fiber-jacketed pipes, wherein metallic pipes are coated with a highly creep-resistant jacket made of a ceramic matrix composite (CMC). This approach not only enables elevated process temperatures and reduced wall thicknesses but also facilitates retrofitting and repairing existing systems. The system is also advantageous in other fields of application like piping and tank systems in chemical industry. The effectiveness of this concept has been validated through two projects, conducted at laboratory and power plant scale. Notably, a fiber-coated pipe bend produced in the second project has been operational for over 25,000 hours in the bypass of a live steam line at GKM power plant. In addition to the successful component test, various simulative and laboratory experiments have been conducted and are ongoing at MPA University of Stuttgart. Design of the jacket-liner system was supported by extensive Finite-Element-calculations in order to simulate the overall and local stress strain behavior of the material system and to predict lifetime of components. The objective of this presentation is to introduce the fiber-jacketed pipe concept and to provide an overview of the ongoing work on the design and qualification of fiber-jacketed pipes at MPA University of Stuttgart.