Ball valve: 

The ball valve is developed on the basis of the plug valve. Its opening and closing part is a ball, which is opened and closed by rotating the ball 90° around the axis of the valve stem. The ball valve is mainly used to cut, distribute and change the flow direction of the medium on the pipeline.

The types of ball valve：

Ball valve generally have floating ball valve,fixed ball valve,one-piece ball valve, two-piece ball valve, three-piece ball valve, soft sealing ball valve,hard sealing ball valve,forged steel ball valve, flanged ball valve, welding ball valve,threaded ends ball valve, thread ball valve , card ball valve, electric ball valve, pneumatic ball valve, hydraulic ball valve, gear ball valve, eccentric ball valve, top-mounted ball valve, stainless steel ball valve, carbon steel ball valve, cast steel ball valve, fluorine-filled ball valve, discharge ball valve, high temperature ball valve,etc.

Plug valve: 

Plug valve refers to a rotary valve in which the closing part is in the shape of a plunger. The valve opening on the valve that plug communicates with or separates from the passage opening on the valve body by 90° rotation to realize a valve that opens or closes. The shape of the plug valve can be cylindrical or conical. The plug valve is a closing or plunger-shaped rotary valve that opens or closes by rotating the passage port on the valve plug 90 degrees or the same as the passage port on the valve body. The plug of the plug valve may be cylindrical or conical in shape. In a cylindrical valve plug, the passage is generally rectangular; in a tapered plug valve, the passage is trapezoidal. These shapes make the structure of the plug valve light, but at the same time cause some loss. 

Plug valves are best suited for use as a shut-off and closing medium as well as for shunting, but can sometimes be used for throttling depending on the nature of the application and the erosion resistance of the sealing surface. It is also commonly used for media with suspended particles due to the wiping action between the sealing surfaces of the plug valve and the complete contact with the flowing medium during full opening. Another important feature of the plug valve is that it is easy to accommodate multi-channel construction so that one valve can achieve two, three, or even four different flow paths. This simplifies the piping system design, reduces valve usage, and some of the connection accessories needed in the equipment.Plug valves are widely used in oilfield mining, transportation and refining equipment, and are also widely used in petrochemical, chemical, gas, natural gas, liquefied petroleum gas, HVAC industry and general industry.these are main difference between ball valve and plug valve.

Although the sealing effect of the ball valve is theoretically slightly poor than plug valve, it can be made into a large diameter, and with the improvement of machining precision and sealing material, the sealing effect of the ball valve can well meet the practical application requirements, and the application range is wider.When used for shutting off, the plug valve has a slightly better adjustment ability than the ball valve, but the advantage is limited. Since the sealing surface of the plug valve is much larger than the ball valve, the sealing effect is good, so the torque is too large, and the action is not flexible enough. The conventional positive cock structure is difficult to achieve a large diameter due to the weight of the cock itself.