DeepC3000 – large corrosion-free pressure housing made of ultra-high performance concrete (UHPC) for depths up to 3,000 m

In the DeepCsolution research project partners from industry and science are working on the development of innovative, non-corrosive high-pressure housings for marine applications. Here we present the new DeepC3000 pressure housing built from an ultra-high performance concrete (UHPC) This special concrete has a strength of more than 150 MPa. Theoperating depth of the housing is up to 3000 m, the outer diameter is 750 mm and an inner volume is 265 dm
³
. The special feature of UHPC pressure housings is that they are corrosion-free, unlike steel and stainless-steel housings. There are already alternative pressure housings made of non-corrosive materials like titanium or ceramic. However, these alternative housings have two main disadvantages compared to UHPC: they are extremely complicated to manufacture and moreover very expensive to produce, especially for large volumes as presented here. In this paper, we describe the development and construction processes of the DeepC3000 housing with a rated depth of 3,000 m and provide first impressions of an application in marine research. We discuss how the idea became reality from the conceptual design to material testing, manufacturing, testing of the structural components and deployment in the deep sea. In addition, other applications of this newly developed pressure housing are discussed. One important design aspect of UHPC pressure housings was, that the tensile strength of the material is only a small fraction of the compressive strength. This affects the design of the pressure housing. On the one hand, a spherical and cylindrical shape was used, which has a very good material efficiency under external hydrostatic pressure. On the other hand, the pressure housing was designed to avoid geometric discontinuities as far as possible, or to make them as smooth as possible in order not to disturb the flow of force. To demonstrate the capabilities of the UHPC, several small and large housings were produced and tested. This includes small-scale experiments and real-scale structural tests in a pressure tank to measure the strains of the concrete on the inside of the housings resulting from the hydrostatic pressure, for example.