A Single piece body designed valve means the valve has a body constructed from one piece.  The valve body may be casted, forged or welded into one piece and machined to the valve body.  Sometimes there are valves which the body is welded into one piece, such as the full welded body ball valve.  The single piece body designed valve has no flanged or bolted joints on the body, thus there is no leakage risk for such valves. Commonly the single piece body valve has limited in assembly, and it is for small sizes valves.

Multi Pieces Body Valves

Multi Pieces Body Ball Valves

Multi Pieces Body Designed Valves