A centrifugal compressorCentrifugal compressor casing houses both stationary and rotating internal components. Stationary elements include the inlet voluteDischarge volute, guide vanes, discharge volute, diaphragms, return channels, sealing systems, and bearingsBearing. The dynamic assembly—referred to as the rotor—comprises the shaft, impellers, and balance drum (or piston). Process nozzles are either welded onto the casing or integrally cast as part of its structure, and provisions are also made for auxiliary piping connections. This chapter offers an in-depth exploration of casing joint types and their pressure-handling capabilities, various casing configurationsCasing configurations, shear ring designs specific to radially split compressors, and the methods used in casing fabricationCasing manufacturing. Additional topics covered include the interface between the casing and its mounting pedestal, design considerations for discharge volutesDischarge volute and nozzle configurations, and the role of water or oil injection in compressor operation.