In recent years the share of renewable energies in the electricity system has constantly grown. The growth is fueled by several national and international initiatives to tackle climate change and become less dependent on fossil fuels. This has already led to a change in electricity production away from conventional fossil fuel towards various renewable energies, mainly wind and photovoltaics. As these produce electricity detached from actual demand the issue of energy storage has come to focus. To store the surplus of energy produced by renewables and to keep a balanced stable grid storage capacity is a key issue. One of the best known storage technologies is pumped storage hydropower, in which water is pumped into a reservoir during times of overproduction, during demand times this water is used to operate turbines to generate electricity. Even though the technology was developed in the 19th century it still is an and has a future as an important part of the energy sector. For this thesis future design concepts for spiral cases for high-head pump storage applications have been studied. As the outputs of the units have increased over the years and so the parts have grown bigger, design options for segmented parts become more important to be able to manufacture, transport and assemble the machines in an effective way. Finite element analysis and a test rig have been used to prove the general applicability of a segmented spiral case for a theoretical pump unit with more than 500 MW output, the finite element analysis has shown that the main structure of the spiral case can be realized in accordance with allowed standard stress levels but due to the unavoidable deformations the issue of sealing the parts during operation has become the main focus. Four sealing concepts have been developed and analyzed. A flat sealing surface, a sealing nose, a sealing carrier and a shrink fit. The best results were achieved with the sealing nose concept, the flat sealing surface and the sealing carrier do not work for the intended pressure staged but might be solutions for related applications. The shrink fit has been exposed to be unsuitable for the studied concept. To prove the sealing ability, especially the T-joint connection of the sealing, a test rig has been developed and acquired. Three kinds of sealings have been tested, a vulcanized O-ring, a loose round cord, and a customized gasket sealing. The best results were achieved with the vulcanized version, 330 bar could be sealed at a gap of 0.2 mm, the loose version could seal the 330 bar until a gap of 0.1 mm, at 0.15 mm leakage appeared at around 140 bar. Unfortunately, the gasket sealing delivered unsatisfying results due to not stabilizing pressure and leakage at around 100 bar. In general, the performed analysis and tests have shown that the concept of a segmented spiral case is feasible even for machines with an output of over 500 MW. It is possible to cover the appearing gaps with the available sealing technology and keep the parts tight even in the highest load cases.
