Ball valves come in three main body configurations, and while they all do the same fundamental job, turning flow on and off with a quarter-turn, the differences between them affect how the valve is installed, how it can be maintained, and how long it lasts in demanding applications.
1-Piece Ball Valves
A 1-piece ball valve has a single body casting with the ball and seats assembled inside and the end connections formed as part of that body. They're compact, low-cost, and completely appropriate for most general-purpose shutoff applications. The trade-off is that they can't be disassembled, so if the ball, seats, or stem seal fail, the valve gets replaced, not repaired. For non-critical applications where the valve will see normal use and isn't in a location where periodic maintenance is expected, 1-piece valves are a practical choice.
2-Piece Ball Valves
A 2-piece valve splits the body into two sections, typically a main body that houses the ball and one end connection, and an end piece that forms the second connection and can be removed from the body. 2-piece valves are the most common configuration in general industrial and process applications, offering a good balance of repairability, pressure rating, and cost.
3-Piece Ball Valves
A 3-piece valve adds a third body section so the valve center, the section housing the ball and seats, can be removed from the two end connections. The additional strength and ability for full disassembly makes the 3-piece a great choice in well used setups.