Gate and ball valves are the two dominant choices for on/off isolation, and on many datasheets either would technically work. The right choice comes down to how often the valve operates, how tight the shutoff must stay over years of service, and what the line size does to the price comparison.
A gate valve lifts a metal wedge out of the flow path with multiple handwheel turns. Sealing is metal-to-metal: reliable, robust and repairable, but rarely bubble-tight after years of cycling. A ball valve rotates a polished ball a quarter turn against resilient seats; soft-seated designs deliver bubble-tight Class VI shutoff from the first cycle to the ten-thousandth.
The 90° stroke is the ball valve's decisive advantage wherever valves cycle often or need actuation. A quarter-turn actuator is compact, cheap and fast; motorising a large gate valve requires a multi-turn actuator with more torque, more travel time and more cost. For emergency shutdown (ESD) duty, ball valves are the default — a spring-return pneumatic ball valve package closes in seconds.
Both valves offer a straight-through bore. A full-bore ball valve matches the pipe internal diameter exactly, which pipeline operators need for pigging — one reason API 6D trunnion ball valves rule transmission pipelines. Gate valves are equally low-loss when fully open, and at very large diameters (40"–60") remain the more economical full-open isolation valve.
Below about 6", floating ball valves are usually cheaper than gate valves and seal better — small-bore isolation has largely migrated to ball valves worldwide. As size and class rise, the machined ball and seats grow expensive; somewhere between 10" and 16" (depending on class) the cast gate valve becomes the economical choice for valves that rarely operate. Both types are available from VTXFLOW in WCB, CF8M and alloy grades with EN 10204 3.1 certificates — send your line list for a same-day comparison quote.