The DBB top-entry ball valve uses a one-piece body and full-bore ball for a high rated flow coefficient and low flow resistance. The ball surface is specially hardened for smoothness and wear resistance. Seat materials include carbon-fiber-reinforced PTFE or stainless steel hard-faced with cobalt-based alloy/hard alloy, providing reliable sealing and long service life. A high-performance double-piston rack-and-pinion actuator offers efficient transmission in a compact package.