These are motor casings for the solid booster motors for ISRO's PSLV launch vehicle.
The motor casings are manufactured in 3 main segments, head end segment, middle segment and nozzle end segment, and have forged domes at the head end and nozzle end. The nozzle end is connected to the nozzle convergent and nozzle divergent, which are machined out of forgings. Entire manufacturing and machining of all these segments, along with manufacturing of interchangability drill jig is being completed at Kay Bouvet Engineering
Materials: 15CDV6
Dimensions: